Workpiece rotational grinding is widely used in the ultra-precision machining of hard and brittle semiconductor materials,including single-crystal silicon,silicon carbide,and gallium arsenide.Surface roughness and sub...Workpiece rotational grinding is widely used in the ultra-precision machining of hard and brittle semiconductor materials,including single-crystal silicon,silicon carbide,and gallium arsenide.Surface roughness and subsurface damage depth(SDD)are crucial indicators for evaluating the surface quality of these materials after grinding.Existing prediction models lack general applicability and do not accurately account for the complex material behavior under grinding conditions.This paper introduces novel models for predicting both surface roughness and SDD in hard and brittle semiconductor materials.The surface roughness model uniquely incorporates the material’s elastic recovery properties,revealing the significant impact of these properties on prediction accuracy.The SDD model is distinguished by its analysis of the interactions between abrasive grits and the workpiece,as well as the mechanisms governing stress-induced damage evolution.The surface roughness model and SDD model both establish a stable relationship with the grit depth of cut(GDC).Additionally,we have developed an analytical relationship between the GDC and grinding process parameters.This,in turn,enables the establishment of an analytical framework for predicting surface roughness and SDD based on grinding process parameters,which cannot be achieved by previous models.The models were validated through systematic experiments on three different semiconductor materials,demonstrating excellent agreement with experimental data,with prediction errors of 6.3%for surface roughness and6.9%for SDD.Additionally,this study identifies variations in elastic recovery and material plasticity as critical factors influencing surface roughness and SDD across different materials.These findings significantly advance the accuracy of predictive models and broaden their applicability for grinding hard and brittle semiconductor materials.展开更多
Thermodynamic models for molecular-beam epitaxy（MBE） growth of ternary Ⅲ-Ⅴ semiconductor materials are proposed.These models are in agreement with our experimental materials InGaP/GaAs and InGaAs/InP,and reported ...Thermodynamic models for molecular-beam epitaxy（MBE） growth of ternary Ⅲ-Ⅴ semiconductor materials are proposed.These models are in agreement with our experimental materials InGaP/GaAs and InGaAs/InP,and reported GaAsP/GaAs and InAsP/InP in thermodynamic growth.The lattice strain energy △G and thermal decomposition sensitive to growth temperature are demonstrated in the models simultaneously.△G is the function of the alloy composition,which is affected by flux ratio and growth temperature directly.The calculation results reveal that flux ratio and growth temperature mainly influence the growth process.Thermodynamic model of quaternary InGaAsP/GaAs semiconductor material is discussed also.展开更多
The essential objective of radiation dosimetry is to develop suitable sensitive materials for different measurements in radiation fields. Our exploration is to find potentially suitable high gamma radiation dosimeters...The essential objective of radiation dosimetry is to develop suitable sensitive materials for different measurements in radiation fields. Our exploration is to find potentially suitable high gamma radiation dosimeters in the range from 0.5E4 to 1.5E4 Gy. Gamma rays source (<sup>60</sup>Co, 136 Gy/min) has been used. Many compound semiconductor materials were prepared and investigated. Thermoluminescence (TL) glow curve was analyzed into its component by analytical segregation program using computerized glow curve deconvolution (CGCD). Three zero dose readings for non-irradiated powders of the materials have been taken as lower limit of detection. The results indicated that some of the tested materials have exhibited TL linearly with respect to dose. In addition, dose response of these materials was found to be useful for high radiation dosimetry. Glow curve structures exhibited several peaks corresponding to the various energies of the emptied traps. Variation in the standard deviation for reusability cycles has been ten readout. The fading at ambient temperature was studied up to 60 days which reached a relative stability (~1.5% for all), 10 days after irradiation. A typical glow curve of CoPa which irradiated with 1.5E4 Gy was analyzed. Characterizations of tested materials indicated that crystals of ZnLa:Li, ZnLa:Cd, and ZnLa:Cr have stable and increasing thermoluminescent responses with high gamma radiation dose range. Special glow peaks can be used as estimators for absorbed doses as well as re-estimation for time elapsed exposures.展开更多
Organic semiconductor materials possess unique advantages in various photoelectric applications.Due to the complicated preparation processes,many impurities are difficult to remove and become extrinsic traps in materi...Organic semiconductor materials possess unique advantages in various photoelectric applications.Due to the complicated preparation processes,many impurities are difficult to remove and become extrinsic traps in materials.However,there exists almost no relevant research on the effects of extrinsic traps on the performance of organic semiconductor materials.In this work,we comprehensively investigate the impacts of ionic traps based on organic photovoltaic(OPV)cells.We demonstrate that the different effects of impurities result from their ionization ability in processing solvent.The ionic traps can induce increased density of trap states and severe trapassist recombination,thereby deteriorating device performance.In addition,we propose a simple method to evaluate the quality of organic semiconductor materials through electrochemical impedance spectroscopy.This research facilitates the batch preparation of organic semiconductor materials and the industrialization of OPV cells.展开更多
High-performance electronics and optoelectronics play vital roles in modern society,as they are the fundamental building blocks of functional devices and systems.Two-dimensional semiconductor materials(2D-SCMs)are pot...High-performance electronics and optoelectronics play vital roles in modern society,as they are the fundamental building blocks of functional devices and systems.Two-dimensional semiconductor materials(2D-SCMs)are potential candidates for highperformance electronics and optoelectronics due to their excellent physical,chemical,electrical,and photonic properties.Owing to their special crystalline structure,they also present unique piezoelectricity,which opens a new door to the innovative fields of piezotronics and piezo-phototronics.Piezotronics and piezophototronics utilize the piezoelectric polarization charges produced when the 2D-SCMs undergo externally applied strains/stresses to modulate the performance of 2D-SCMs-based electronics and optoelectronics.In this review,firstly,the growth methods and piezoelectric properties of 2D-SCMs are stated,and the mechanisms of piezotronics and piezo-phototronics are also introduced.Afterwards,the recent progress of piezotronics and piezo-phototronics in high-performance 2D-SMCs-based electronics and optoelectronics are systematically reviewed.In addition,the functional devices and systems based on the piezotronics and piezo-phototronics in 2D-SMCs have been summarized.Finally,the research progresses are summarized,and future perspectives are proposed.展开更多
This paper reviews the studies on acoustoelectric effect in extrinsic semiconductor materials used in various scientific and other measurements. A historical review of earlier findings is given with special reference ...This paper reviews the studies on acoustoelectric effect in extrinsic semiconductor materials used in various scientific and other measurements. A historical review of earlier findings is given with special reference to associated mechanisms. Acoustoelectric studies in solid state devioes require further attention and the work done in this area is also discussed.展开更多
Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic a...Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic absorption,(2)modulation spectroscopy,and(3)the most widely used Tauc-plot.The excitonic absorption is based on a many-particle theory,which is physically the most correct approach,but requires more stringent crystalline quality and appropriate sample preparation and experimental implementation.The Tauc-plot is based on a single-particle theo⁃ry that neglects the many-electron effects.Modulation spectroscopy analyzes the spectroscopy features in the derivative spectrum,typically,of the reflectance and transmission under an external perturbation.Empirically,the bandgap ener⁃gy derived from the three approaches follow the order of E_(ex)>E_(MS)>E_(TP),where three transition energies are from exci⁃tonic absorption,modulation spectroscopy,and Tauc-plot,respectively.In principle,defining E_(g) as the single-elec⁃tron bandgap,we expect E_(g)>E_(ex),thus,E_(g)>E_(TP).In the literature,E_(TP) is often interpreted as E_(g),which is conceptual⁃ly problematic.However,in many cases,because the excitonic peaks are not readily identifiable,the inconsistency be⁃tween E_(g) and E_(TP) becomes invisible.In this brief review,real world examples are used(1)to illustrate how excitonic absorption features depend sensitively on the sample and measurement conditions;(2)to demonstrate the differences between E_(ex),E_(MS),and E_(TP) when they can be extracted simultaneously for one sample;and(3)to show how the popular⁃ly adopted Tauc-plot could lead to misleading results.Finally,it is pointed out that if the excitonic absorption is not ob⁃servable,the modulation spectroscopy can often yield a more useful and reasonable bandgap than Tauc-plot.展开更多
By combining neuroevolution potential(NEP)with phonon Boltzmann transport theory,we systematically investigate the thermal transport properties of three two-dimensional(2D)narrow bandgap semiconductors:Ca_(3)N_(2),Ba_...By combining neuroevolution potential(NEP)with phonon Boltzmann transport theory,we systematically investigate the thermal transport properties of three two-dimensional(2D)narrow bandgap semiconductors:Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2).The room-temperature lattice thermal conductivities(κ_(L))of Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2)considering only three-phonon scattering are 6.60 W/m K,11.90 W/m K,and 8.88 W/m K,respectively.When taking into account the higherorder phonon(four-phonon)scattering processes,theκL of these three materials decrease to 6.12 W/m K,9.73 W/m K and6.77 W/m K,respectively.Among these systems,Ba_(3)As_(2)undergoes the most pronounced suppression with a reduction of 23.8%.This is mainly due to the greater scattering phase space which enhances the four-phonon scattering.Meanwhile,it is revealed that unlike the traditional evaluation using the P_(4)/P_(3)ratio as an indicator of the strength of four-phonon interactions,the thermal conductivity of Ba_(3)P_(2)exhibits weaker four-phonon suppression behavior compared to Ba_(3)As_(2),despite hosting a higher P_(4)/P_(3)ratio.That is to say,the strength of four-phonon scattering cannot be evaluated solely by the ratio of P_(4)/P_(3).These results presented in this work shed light on the thermal transport properties of such new 2D semiconductors with narrow bandgaps.展开更多
In this paper, we report the growth of single crystals of Co_x Zn_(1-x)S and Co_x Zn_(1-x)Se (0<x<0.3) by the method of chemical transport, using iodine as a transport agent. The light green color of single crys...In this paper, we report the growth of single crystals of Co_x Zn_(1-x)S and Co_x Zn_(1-x)Se (0<x<0.3) by the method of chemical transport, using iodine as a transport agent. The light green color of single crystal Co_xZn_(1-x)S as well as the light brown color of Co_xZn_(1-x)Se become deep with an increase in x. The compositions of the single crystals were nearly stoichiometric. The transfer rate decreases with an increase of the x value. The growth rate was related to the temperature difference. The large temperature difference speed up the growth rate, but the size of crystal obtained was small. In general, the optimal temperature difference was 15℃. From X-ray diffraction measurements, the structures of crystals Co_xZn_(1-x)S and Co_xZn_(1-x)Se (0<x<0.1) were identified to be zinc blende structure similar to that of ZnS and ZnSe.展开更多
Direct alcohol fuel cells(DAFCs)have received wide attention as a new type of clean energy device because of their high energy conversion efficiency,portability,non-toxicity and pollution-free.Anode catalysts are the ...Direct alcohol fuel cells(DAFCs)have received wide attention as a new type of clean energy device because of their high energy conversion efficiency,portability,non-toxicity and pollution-free.Anode catalysts are the key factors affecting the performance of DAFCs.Recently studies show that using the optical activity of semiconductor materials as the carriers of traditional precious metal electrocatalysts,under the illumination of light sources,can greatly improve the electrocatalytic activity and stability of electrodes.In this review,the research progress of photo-responsive metal/semiconductor hybrids as the electrocatalysts for DAFCs in recent years is summarized,including:(1)Mechanism and advantages of photo-assistant electrochemical alcohol oxidation reaction,(2)me tal/semiconductor electrocatalyst for the different type of fuel cell reactions,(3)different kind of metals in photo-responsive metal/semiconductor hybrid nanostructure,(4)the personal prospects of the photo-responsive metal/semiconductor electrode for future application in DAFCs.展开更多
Semiconductor materials exemplify humanity's unwavering pursuit of enhanced performance,efficiency,and functionality in electronic devices.From its early iterations to the advanced variants of today,this field has...Semiconductor materials exemplify humanity's unwavering pursuit of enhanced performance,efficiency,and functionality in electronic devices.From its early iterations to the advanced variants of today,this field has undergone an extraordinary evolution.As the reliability requirements of integrated circuits continue to increase,the industry is placing greater emphasis on the crystal qualities.Consequently,conducting a range of characterization tests on the crystals has become necessary.This paper will examine the correlation between crystal quality,device performance,and production yield,emphasizing the significance of crystal characterization tests and the important role of high-precision synchrotron radiation X-ray topography characterization in semiconductor analysis.Finally,we will cover the specific applications of synchrotron radiation characterization in the development of semiconductor materials.展开更多
Abstract: The Raman scattering spectra of n- type GaP(doped S) single crystal and red and green luminous materials grown on the n - type GaP (doped S) single crys-tal substrate by liquid - phase epitaxy are analyed. T...Abstract: The Raman scattering spectra of n- type GaP(doped S) single crystal and red and green luminous materials grown on the n - type GaP (doped S) single crys-tal substrate by liquid - phase epitaxy are analyed. The results show that the spectra of GaP single crystal and its luminous materials include not only the first - order longitudi-nal optical photons and transverse optical phonons Raman scattering peaks, but also the peaks of the bound excitons, bound electrons and bound holes.展开更多
The electroluminescunce (EL) transient characteristics of erbium-doped zinc sulfide thin film (TF) devices excited by short rectangular pulses are studied, the luminescence delay after de-exciting and the relaxation l...The electroluminescunce (EL) transient characteristics of erbium-doped zinc sulfide thin film (TF) devices excited by short rectangular pulses are studied, the luminescence delay after de-exciting and the relaxation luminance peaks during decay are observed. A model description for energy transfer has been proposed. The experimental results can be theoretically explained with the computer curve fittings.展开更多
The wide band gap characteristics of gallium oxide make it very suitable for the preparation of solar-blind ultra-violet photodetectors.The responsivity of ultraviolet photodetectors based on thin films is often low.H...The wide band gap characteristics of gallium oxide make it very suitable for the preparation of solar-blind ultra-violet photodetectors.The responsivity of ultraviolet photodetectors based on thin films is often low.However,nanomaterials have excellent photoelectric properties in device applications due to the high stability brought by high specific surface area and high crystal quality.Here,we successfully depositedβ-Ga_(2)O_(3) nanopores on the double-pass ordered porous AAO tem-plate by PLD.The porous AAO template is used as the growth space of nanomaterials,and the gallium oxide material is filled into the pores of the template to form a nanotube structure.By optimizing the preparation process,the relationship be-tween the performance of gallium oxide nanopores and the growth time was studied in depth.With the increase of growth time,the responsivity of the detector was improved.The rise timeτr=0.7 s,the decay timeτ_(d)=1.3 s,and the responsivity reached 4.63 mA·W^(-1),which was higher than 2.24 mA·W^(-1)of the responsivity of silicon-based gallium oxide nanorods.展开更多
Metal halide perovskites, as a novel class of semiconductor optoelectronic materials, combine the excellent optoelectronic properties of inorganic semiconductors with the advantages of low-cost, printable fabrication ...Metal halide perovskites, as a novel class of semiconductor optoelectronic materials, combine the excellent optoelectronic properties of inorganic semiconductors with the advantages of low-cost, printable fabrication typical of organic semiconductors, making them a cutting-edge research focus in the field of semiconductor optoelectronic devices.展开更多
Silicon carbide (SiC) single crystal,which hasn’t melting point at normal pressu r e and sublimates at temperature above 2000℃,is a wide bandgap semiconductor.Si lic on carbide has more than 200 kinds of polytype.Am...Silicon carbide (SiC) single crystal,which hasn’t melting point at normal pressu r e and sublimates at temperature above 2000℃,is a wide bandgap semiconductor.Si lic on carbide has more than 200 kinds of polytype.Among these polytypes,3C SiC、6H SiC and 4H SiC are the most common ones,the band width of them are 2.4eV,3.0eV , an d 3.4eV,restpectively.For its high temperature tolerance and radiation resistanc e,silicon carbide semiconductor can be extensively used to fabricate the power d evi ces and electroluminescence devices operating at high power,high frequency and high radiation environments. The aim of this paper is to introduce our research results of the growth of larg e SiC single crystals by physical vapor transport method.The seed is SiC single crystal wafer with perfect (0001)Si face,which is chosen from the furnace growi ng the green abrasive material of SiC in industry.The source is green powder of SiC .The seed and the source are placed into the graphite crucible of a graphite res i stively heated vacuum furnace.The growth chamber is filled with the atmosphere o f pure araon.When the temperature of source rises to 2300℃,the crystal growth p ro ceeds.The rate of crystal growth is dependent on the growth temperature,the pres sure in furnace and the temperature gradient and distance between the seed and t h e source.Under the controlled growth conditions,the bulk SiC crystal with a diam eter of 40mm and a thickness of 15mm is obtained.The crystal appears to be n type electrical conductivity,the results of X ray Laue photography analysis indicat e that it is 6H SiC polytype.The defects of the crystal are also studied by many kinds of method.展开更多
Under hydrothermal and solvothermal conditions,two novel cobalt-based complexes,{[Co_(2)(CIA)(OH)(1,4-dtb)]·3.2H_(2)O}n(HU23)and{[Co_(2)(CIA)(OH)(1,4-dib)]·3.5H2O·DMF}n(HU24),were successfully construct...Under hydrothermal and solvothermal conditions,two novel cobalt-based complexes,{[Co_(2)(CIA)(OH)(1,4-dtb)]·3.2H_(2)O}n(HU23)and{[Co_(2)(CIA)(OH)(1,4-dib)]·3.5H2O·DMF}n(HU24),were successfully constructed by coordinatively assembling the semi-rigid multidentate ligand 5-(1-carboxyethoxy)isophthalic acid(H₃CIA)with the Nheterocyclic ligands 1,4-di(4H-1,2,4-triazol-4-yl)benzene(1,4-dtb)and 1,4-di(1H-imidazol-1-yl)benzene(1,4-dib),respectively,around Co^(2+)ions.Single-crystal X-ray diffraction analysis revealed that in both complexes HU23 and HU24,the CIA^(3-)anions adopt aκ^(7)-coordination mode,bridging six Co^(2+)ions via their five carboxylate oxygen atoms and one ether oxygen atom.This linkage forms tetranuclear[Co4(μ3-OH)2]^(6+)units.These Co-oxo cluster units were interconnected by CIA^(3-)anions to assemble into 2D kgd-type structures featuring a 3,6-connected topology.The 2D layers were further connected by 1,4-dtb and 1,4-dib,resulting in 3D pillar-layered frameworks for HU23 and HU24.Notably,despite the similar configurations of 1,4-dtb and 1,4-dib,differences in their coordination spatial orientations lead to topological divergence in the 3D frameworks of HU23 and HU24.Topological analysis indicates that the frameworks of HU23 and HU24 can be simplified into a 3,10-connected net(point symbol:(4^(10).6^(3).8^(2))(4^(3))_(2))and a 3,8-connected tfz-d net(point symbol:(4^(3))_(2)((4^(6).6^(18).8^(4)))),respectively.This structural differentiation confirms the precise regulatory role of ligands on the topology of metal-organic frameworks.Moreover,the ultraviolet-visible absorption spectra confirmed that HU23 and HU24 have strong absorption capabilities for ultraviolet and visible light.According to the Kubelka-Munk method,their bandwidths were 2.15 and 2.08 eV,respectively,which are consistent with those of typical semiconductor materials.Variable-temperature magnetic susceptibility measurements(2-300 K)revealed significant antiferromagnetic coupling in both complexes,with their effective magnetic moments decreasing markedly as the temperature lowered.CCDC:2457554,HU23;2457553,HU24.展开更多
Wurtzite structure gallium nitride GaN,a direct bandgap semiconductor,is an ideal material for fabrication of blue/green light emitting diodes,laser diodes, and high powder Integrated Circuites.Up to now,small single ...Wurtzite structure gallium nitride GaN,a direct bandgap semiconductor,is an ideal material for fabrication of blue/green light emitting diodes,laser diodes, and high powder Integrated Circuites.Up to now,small single crystals,powders and nanomaterials of GaN have successfully synthesized as well as applied films gro wn by MOCVD.In this report,another condensed state of GaN,nanocrystal assembled bulk,was synthesized and its spectra are investigated. Metal gallium or gallium alloys are used as starting materials and haloids used as catalyzer in ammonia.Buff transparent GaN bulks were obtained at 350—500℃.P owder X ray diffraction indicated that the bulks are wurtaite GaN single phase. HRTEM confirmed that the bulks are composed of nanoparticles with average size o f 12mm.The well crystallized particle shows clear diffraction spots.PL spectra of the material are similar to that of GaN singe crystals under the ultraviolet excitation,but blue shift is observed near gap band.Red shift occurs in Raman scattering comparing with single crystals.The materials have the broad potential in the future because it not only possesses of mechanical and optical characteri stics owned by single crystals but also holds the nano properties of the nanoma terials.展开更多
Hexagonal gallium nitride films were successfully fabricated throughammoniating Ga_2O_3 films deposited on silicon (111) substrates by electrophoresis. The structure,composition, and surface morphology of the formed f...Hexagonal gallium nitride films were successfully fabricated throughammoniating Ga_2O_3 films deposited on silicon (111) substrates by electrophoresis. The structure,composition, and surface morphology of the formed films were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmissionelectron microscopy (TEM). The measurement results reveal that the polycrystalline GaN films withhexagonal wurtzite structure were successfully grown on the silicon (111) substrates. Preliminaryresults suggest that varying the ammoniating temperature has obvious effect on the quality of theGaN films formed with this method.展开更多
Bilayered FTO/AZO （fluorine doped tin oxide/aluminium doped zinc oxide） films were fabricated using a simple, cost effective spray pyrolysis technique. X-ray diffraction （XRD） profiles of bilayered films showed th...Bilayered FTO/AZO （fluorine doped tin oxide/aluminium doped zinc oxide） films were fabricated using a simple, cost effective spray pyrolysis technique. X-ray diffraction （XRD） profiles of bilayered films showed that in the case of lower thickness FTO over layers, （002） plane of ZnO phase had the highest intensity, whereas the predominance was changed in favour of （200） plane of SnO2 phase for higher thickness FTO over layer. UV studies showed that bilayered FTO/AZO films exhibited a sharp absorption edge as that of AZO film. The decrease in the photoluminescence （PL） peak at 420 nm with increasing FTO over layer thickness indicated a reduction in the zinc vacancies which caused a reduction in the sheet resistance （Rsh）. Electrical studies revealed that, eventhough the Rsh value （916Ω/□） of bilayered FTO （313 nm）/AZO （314 nm） film was found to be higher than that of FTO single layer film （72Ω/□）, it was much lower than that of AZO single layer film （5661Ω/□））. The atomic force microscopy （AFM） images reflect the characteristic features of both zinc oxide and tin oxide films.展开更多
基金supported by the National Key Research and Development Program of China(2022YFB3605902)the National Natural Science Foundation of China(52375411,52293402)。
文摘Workpiece rotational grinding is widely used in the ultra-precision machining of hard and brittle semiconductor materials,including single-crystal silicon,silicon carbide,and gallium arsenide.Surface roughness and subsurface damage depth(SDD)are crucial indicators for evaluating the surface quality of these materials after grinding.Existing prediction models lack general applicability and do not accurately account for the complex material behavior under grinding conditions.This paper introduces novel models for predicting both surface roughness and SDD in hard and brittle semiconductor materials.The surface roughness model uniquely incorporates the material’s elastic recovery properties,revealing the significant impact of these properties on prediction accuracy.The SDD model is distinguished by its analysis of the interactions between abrasive grits and the workpiece,as well as the mechanisms governing stress-induced damage evolution.The surface roughness model and SDD model both establish a stable relationship with the grit depth of cut(GDC).Additionally,we have developed an analytical relationship between the GDC and grinding process parameters.This,in turn,enables the establishment of an analytical framework for predicting surface roughness and SDD based on grinding process parameters,which cannot be achieved by previous models.The models were validated through systematic experiments on three different semiconductor materials,demonstrating excellent agreement with experimental data,with prediction errors of 6.3%for surface roughness and6.9%for SDD.Additionally,this study identifies variations in elastic recovery and material plasticity as critical factors influencing surface roughness and SDD across different materials.These findings significantly advance the accuracy of predictive models and broaden their applicability for grinding hard and brittle semiconductor materials.
基金Projects(06YFJZJC01100,08JCYBJC14800)supported by Applied Basic Study Foundation of Tianjin,ChinaProject(2006AA03Z413)supported by the Hi-tech Research and Development Program of China
文摘Thermodynamic models for molecular-beam epitaxy（MBE） growth of ternary Ⅲ-Ⅴ semiconductor materials are proposed.These models are in agreement with our experimental materials InGaP/GaAs and InGaAs/InP,and reported GaAsP/GaAs and InAsP/InP in thermodynamic growth.The lattice strain energy △G and thermal decomposition sensitive to growth temperature are demonstrated in the models simultaneously.△G is the function of the alloy composition,which is affected by flux ratio and growth temperature directly.The calculation results reveal that flux ratio and growth temperature mainly influence the growth process.Thermodynamic model of quaternary InGaAsP/GaAs semiconductor material is discussed also.
文摘The essential objective of radiation dosimetry is to develop suitable sensitive materials for different measurements in radiation fields. Our exploration is to find potentially suitable high gamma radiation dosimeters in the range from 0.5E4 to 1.5E4 Gy. Gamma rays source (<sup>60</sup>Co, 136 Gy/min) has been used. Many compound semiconductor materials were prepared and investigated. Thermoluminescence (TL) glow curve was analyzed into its component by analytical segregation program using computerized glow curve deconvolution (CGCD). Three zero dose readings for non-irradiated powders of the materials have been taken as lower limit of detection. The results indicated that some of the tested materials have exhibited TL linearly with respect to dose. In addition, dose response of these materials was found to be useful for high radiation dosimetry. Glow curve structures exhibited several peaks corresponding to the various energies of the emptied traps. Variation in the standard deviation for reusability cycles has been ten readout. The fading at ambient temperature was studied up to 60 days which reached a relative stability (~1.5% for all), 10 days after irradiation. A typical glow curve of CoPa which irradiated with 1.5E4 Gy was analyzed. Characterizations of tested materials indicated that crystals of ZnLa:Li, ZnLa:Cd, and ZnLa:Cr have stable and increasing thermoluminescent responses with high gamma radiation dose range. Special glow peaks can be used as estimators for absorbed doses as well as re-estimation for time elapsed exposures.
基金supported by National Key Research and Development Program of China(grant no.2022YFF0709900)the National Natural Science Foundation of China(grant no.22322904)support from the Youth Innovation Promotion Association CAS(grant no.2023036).
文摘Organic semiconductor materials possess unique advantages in various photoelectric applications.Due to the complicated preparation processes,many impurities are difficult to remove and become extrinsic traps in materials.However,there exists almost no relevant research on the effects of extrinsic traps on the performance of organic semiconductor materials.In this work,we comprehensively investigate the impacts of ionic traps based on organic photovoltaic(OPV)cells.We demonstrate that the different effects of impurities result from their ionization ability in processing solvent.The ionic traps can induce increased density of trap states and severe trapassist recombination,thereby deteriorating device performance.In addition,we propose a simple method to evaluate the quality of organic semiconductor materials through electrochemical impedance spectroscopy.This research facilitates the batch preparation of organic semiconductor materials and the industrialization of OPV cells.
基金supported by the National Natural Science Foundation of China(Grant No.62174131 and 61704135)the China Postdoctoral Science Foundation(Grant No.2018T111055 and 2017M613138)the Postdoctoral Research Project of Shaanxi Province(Grant No.2017BSHEDZZ30).
文摘High-performance electronics and optoelectronics play vital roles in modern society,as they are the fundamental building blocks of functional devices and systems.Two-dimensional semiconductor materials(2D-SCMs)are potential candidates for highperformance electronics and optoelectronics due to their excellent physical,chemical,electrical,and photonic properties.Owing to their special crystalline structure,they also present unique piezoelectricity,which opens a new door to the innovative fields of piezotronics and piezo-phototronics.Piezotronics and piezophototronics utilize the piezoelectric polarization charges produced when the 2D-SCMs undergo externally applied strains/stresses to modulate the performance of 2D-SCMs-based electronics and optoelectronics.In this review,firstly,the growth methods and piezoelectric properties of 2D-SCMs are stated,and the mechanisms of piezotronics and piezo-phototronics are also introduced.Afterwards,the recent progress of piezotronics and piezo-phototronics in high-performance 2D-SMCs-based electronics and optoelectronics are systematically reviewed.In addition,the functional devices and systems based on the piezotronics and piezo-phototronics in 2D-SMCs have been summarized.Finally,the research progresses are summarized,and future perspectives are proposed.
文摘This paper reviews the studies on acoustoelectric effect in extrinsic semiconductor materials used in various scientific and other measurements. A historical review of earlier findings is given with special reference to associated mechanisms. Acoustoelectric studies in solid state devioes require further attention and the work done in this area is also discussed.
基金Supported by Bissell Distinguished Professor Endowment Fund at UNC-Charlotte。
文摘Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic absorption,(2)modulation spectroscopy,and(3)the most widely used Tauc-plot.The excitonic absorption is based on a many-particle theory,which is physically the most correct approach,but requires more stringent crystalline quality and appropriate sample preparation and experimental implementation.The Tauc-plot is based on a single-particle theo⁃ry that neglects the many-electron effects.Modulation spectroscopy analyzes the spectroscopy features in the derivative spectrum,typically,of the reflectance and transmission under an external perturbation.Empirically,the bandgap ener⁃gy derived from the three approaches follow the order of E_(ex)>E_(MS)>E_(TP),where three transition energies are from exci⁃tonic absorption,modulation spectroscopy,and Tauc-plot,respectively.In principle,defining E_(g) as the single-elec⁃tron bandgap,we expect E_(g)>E_(ex),thus,E_(g)>E_(TP).In the literature,E_(TP) is often interpreted as E_(g),which is conceptual⁃ly problematic.However,in many cases,because the excitonic peaks are not readily identifiable,the inconsistency be⁃tween E_(g) and E_(TP) becomes invisible.In this brief review,real world examples are used(1)to illustrate how excitonic absorption features depend sensitively on the sample and measurement conditions;(2)to demonstrate the differences between E_(ex),E_(MS),and E_(TP) when they can be extracted simultaneously for one sample;and(3)to show how the popular⁃ly adopted Tauc-plot could lead to misleading results.Finally,it is pointed out that if the excitonic absorption is not ob⁃servable,the modulation spectroscopy can often yield a more useful and reasonable bandgap than Tauc-plot.
基金supported by the National Natural Science Foundation of China(Grant No.52372260)the Science Fund for Distinguished Young Scholars of Hunan Province(Grant Nos.2024JJ2048 and 2021JJ10036)+1 种基金the Science and Technology Innovation Program of Hunan Province(Grant No.2022RC1197)the Scientific Research Fund of Hunan Provincial Education Department(Grant No.22B0512)。
文摘By combining neuroevolution potential(NEP)with phonon Boltzmann transport theory,we systematically investigate the thermal transport properties of three two-dimensional(2D)narrow bandgap semiconductors:Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2).The room-temperature lattice thermal conductivities(κ_(L))of Ca_(3)N_(2),Ba_(3)P_(2),and Ba_(3)As_(2)considering only three-phonon scattering are 6.60 W/m K,11.90 W/m K,and 8.88 W/m K,respectively.When taking into account the higherorder phonon(four-phonon)scattering processes,theκL of these three materials decrease to 6.12 W/m K,9.73 W/m K and6.77 W/m K,respectively.Among these systems,Ba_(3)As_(2)undergoes the most pronounced suppression with a reduction of 23.8%.This is mainly due to the greater scattering phase space which enhances the four-phonon scattering.Meanwhile,it is revealed that unlike the traditional evaluation using the P_(4)/P_(3)ratio as an indicator of the strength of four-phonon interactions,the thermal conductivity of Ba_(3)P_(2)exhibits weaker four-phonon suppression behavior compared to Ba_(3)As_(2),despite hosting a higher P_(4)/P_(3)ratio.That is to say,the strength of four-phonon scattering cannot be evaluated solely by the ratio of P_(4)/P_(3).These results presented in this work shed light on the thermal transport properties of such new 2D semiconductors with narrow bandgaps.
文摘In this paper, we report the growth of single crystals of Co_x Zn_(1-x)S and Co_x Zn_(1-x)Se (0<x<0.3) by the method of chemical transport, using iodine as a transport agent. The light green color of single crystal Co_xZn_(1-x)S as well as the light brown color of Co_xZn_(1-x)Se become deep with an increase in x. The compositions of the single crystals were nearly stoichiometric. The transfer rate decreases with an increase of the x value. The growth rate was related to the temperature difference. The large temperature difference speed up the growth rate, but the size of crystal obtained was small. In general, the optimal temperature difference was 15℃. From X-ray diffraction measurements, the structures of crystals Co_xZn_(1-x)S and Co_xZn_(1-x)Se (0<x<0.1) were identified to be zinc blende structure similar to that of ZnS and ZnSe.
基金the National Natural Science Foundation of China(Nos.21603111,51702173)Guangdong Basic and Applied Basic Research Foundation(No.2020B1515020038)the Pearl River Talent Recruitment Program of Guangdong Province(No.2019QN01L148)。
文摘Direct alcohol fuel cells(DAFCs)have received wide attention as a new type of clean energy device because of their high energy conversion efficiency,portability,non-toxicity and pollution-free.Anode catalysts are the key factors affecting the performance of DAFCs.Recently studies show that using the optical activity of semiconductor materials as the carriers of traditional precious metal electrocatalysts,under the illumination of light sources,can greatly improve the electrocatalytic activity and stability of electrodes.In this review,the research progress of photo-responsive metal/semiconductor hybrids as the electrocatalysts for DAFCs in recent years is summarized,including:(1)Mechanism and advantages of photo-assistant electrochemical alcohol oxidation reaction,(2)me tal/semiconductor electrocatalyst for the different type of fuel cell reactions,(3)different kind of metals in photo-responsive metal/semiconductor hybrid nanostructure,(4)the personal prospects of the photo-responsive metal/semiconductor electrode for future application in DAFCs.
基金This work was supported by Youth Innovation Promotion Association CAS,National Natural Science Foundation of China(Grant No.11705263)Shanghai Rising-Star Program(Grant No.21QA1410900)。
文摘Semiconductor materials exemplify humanity's unwavering pursuit of enhanced performance,efficiency,and functionality in electronic devices.From its early iterations to the advanced variants of today,this field has undergone an extraordinary evolution.As the reliability requirements of integrated circuits continue to increase,the industry is placing greater emphasis on the crystal qualities.Consequently,conducting a range of characterization tests on the crystals has become necessary.This paper will examine the correlation between crystal quality,device performance,and production yield,emphasizing the significance of crystal characterization tests and the important role of high-precision synchrotron radiation X-ray topography characterization in semiconductor analysis.Finally,we will cover the specific applications of synchrotron radiation characterization in the development of semiconductor materials.
文摘Abstract: The Raman scattering spectra of n- type GaP(doped S) single crystal and red and green luminous materials grown on the n - type GaP (doped S) single crys-tal substrate by liquid - phase epitaxy are analyed. The results show that the spectra of GaP single crystal and its luminous materials include not only the first - order longitudi-nal optical photons and transverse optical phonons Raman scattering peaks, but also the peaks of the bound excitons, bound electrons and bound holes.
文摘The electroluminescunce (EL) transient characteristics of erbium-doped zinc sulfide thin film (TF) devices excited by short rectangular pulses are studied, the luminescence delay after de-exciting and the relaxation luminance peaks during decay are observed. A model description for energy transfer has been proposed. The experimental results can be theoretically explained with the computer curve fittings.
文摘The wide band gap characteristics of gallium oxide make it very suitable for the preparation of solar-blind ultra-violet photodetectors.The responsivity of ultraviolet photodetectors based on thin films is often low.However,nanomaterials have excellent photoelectric properties in device applications due to the high stability brought by high specific surface area and high crystal quality.Here,we successfully depositedβ-Ga_(2)O_(3) nanopores on the double-pass ordered porous AAO tem-plate by PLD.The porous AAO template is used as the growth space of nanomaterials,and the gallium oxide material is filled into the pores of the template to form a nanotube structure.By optimizing the preparation process,the relationship be-tween the performance of gallium oxide nanopores and the growth time was studied in depth.With the increase of growth time,the responsivity of the detector was improved.The rise timeτr=0.7 s,the decay timeτ_(d)=1.3 s,and the responsivity reached 4.63 mA·W^(-1),which was higher than 2.24 mA·W^(-1)of the responsivity of silicon-based gallium oxide nanorods.
文摘Metal halide perovskites, as a novel class of semiconductor optoelectronic materials, combine the excellent optoelectronic properties of inorganic semiconductors with the advantages of low-cost, printable fabrication typical of organic semiconductors, making them a cutting-edge research focus in the field of semiconductor optoelectronic devices.
文摘Silicon carbide (SiC) single crystal,which hasn’t melting point at normal pressu r e and sublimates at temperature above 2000℃,is a wide bandgap semiconductor.Si lic on carbide has more than 200 kinds of polytype.Among these polytypes,3C SiC、6H SiC and 4H SiC are the most common ones,the band width of them are 2.4eV,3.0eV , an d 3.4eV,restpectively.For its high temperature tolerance and radiation resistanc e,silicon carbide semiconductor can be extensively used to fabricate the power d evi ces and electroluminescence devices operating at high power,high frequency and high radiation environments. The aim of this paper is to introduce our research results of the growth of larg e SiC single crystals by physical vapor transport method.The seed is SiC single crystal wafer with perfect (0001)Si face,which is chosen from the furnace growi ng the green abrasive material of SiC in industry.The source is green powder of SiC .The seed and the source are placed into the graphite crucible of a graphite res i stively heated vacuum furnace.The growth chamber is filled with the atmosphere o f pure araon.When the temperature of source rises to 2300℃,the crystal growth p ro ceeds.The rate of crystal growth is dependent on the growth temperature,the pres sure in furnace and the temperature gradient and distance between the seed and t h e source.Under the controlled growth conditions,the bulk SiC crystal with a diam eter of 40mm and a thickness of 15mm is obtained.The crystal appears to be n type electrical conductivity,the results of X ray Laue photography analysis indicat e that it is 6H SiC polytype.The defects of the crystal are also studied by many kinds of method.
文摘Under hydrothermal and solvothermal conditions,two novel cobalt-based complexes,{[Co_(2)(CIA)(OH)(1,4-dtb)]·3.2H_(2)O}n(HU23)and{[Co_(2)(CIA)(OH)(1,4-dib)]·3.5H2O·DMF}n(HU24),were successfully constructed by coordinatively assembling the semi-rigid multidentate ligand 5-(1-carboxyethoxy)isophthalic acid(H₃CIA)with the Nheterocyclic ligands 1,4-di(4H-1,2,4-triazol-4-yl)benzene(1,4-dtb)and 1,4-di(1H-imidazol-1-yl)benzene(1,4-dib),respectively,around Co^(2+)ions.Single-crystal X-ray diffraction analysis revealed that in both complexes HU23 and HU24,the CIA^(3-)anions adopt aκ^(7)-coordination mode,bridging six Co^(2+)ions via their five carboxylate oxygen atoms and one ether oxygen atom.This linkage forms tetranuclear[Co4(μ3-OH)2]^(6+)units.These Co-oxo cluster units were interconnected by CIA^(3-)anions to assemble into 2D kgd-type structures featuring a 3,6-connected topology.The 2D layers were further connected by 1,4-dtb and 1,4-dib,resulting in 3D pillar-layered frameworks for HU23 and HU24.Notably,despite the similar configurations of 1,4-dtb and 1,4-dib,differences in their coordination spatial orientations lead to topological divergence in the 3D frameworks of HU23 and HU24.Topological analysis indicates that the frameworks of HU23 and HU24 can be simplified into a 3,10-connected net(point symbol:(4^(10).6^(3).8^(2))(4^(3))_(2))and a 3,8-connected tfz-d net(point symbol:(4^(3))_(2)((4^(6).6^(18).8^(4)))),respectively.This structural differentiation confirms the precise regulatory role of ligands on the topology of metal-organic frameworks.Moreover,the ultraviolet-visible absorption spectra confirmed that HU23 and HU24 have strong absorption capabilities for ultraviolet and visible light.According to the Kubelka-Munk method,their bandwidths were 2.15 and 2.08 eV,respectively,which are consistent with those of typical semiconductor materials.Variable-temperature magnetic susceptibility measurements(2-300 K)revealed significant antiferromagnetic coupling in both complexes,with their effective magnetic moments decreasing markedly as the temperature lowered.CCDC:2457554,HU23;2457553,HU24.
文摘Wurtzite structure gallium nitride GaN,a direct bandgap semiconductor,is an ideal material for fabrication of blue/green light emitting diodes,laser diodes, and high powder Integrated Circuites.Up to now,small single crystals,powders and nanomaterials of GaN have successfully synthesized as well as applied films gro wn by MOCVD.In this report,another condensed state of GaN,nanocrystal assembled bulk,was synthesized and its spectra are investigated. Metal gallium or gallium alloys are used as starting materials and haloids used as catalyzer in ammonia.Buff transparent GaN bulks were obtained at 350—500℃.P owder X ray diffraction indicated that the bulks are wurtaite GaN single phase. HRTEM confirmed that the bulks are composed of nanoparticles with average size o f 12mm.The well crystallized particle shows clear diffraction spots.PL spectra of the material are similar to that of GaN singe crystals under the ultraviolet excitation,but blue shift is observed near gap band.Red shift occurs in Raman scattering comparing with single crystals.The materials have the broad potential in the future because it not only possesses of mechanical and optical characteri stics owned by single crystals but also holds the nano properties of the nanoma terials.
基金This work is financially supported by the Key Research Program of National Natural Science Foundation of China (No. 90201025)the National Natural Science Foundation of China (No. 60071006)
文摘Hexagonal gallium nitride films were successfully fabricated throughammoniating Ga_2O_3 films deposited on silicon (111) substrates by electrophoresis. The structure,composition, and surface morphology of the formed films were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmissionelectron microscopy (TEM). The measurement results reveal that the polycrystalline GaN films withhexagonal wurtzite structure were successfully grown on the silicon (111) substrates. Preliminaryresults suggest that varying the ammoniating temperature has obvious effect on the quality of theGaN films formed with this method.
基金The financial support from the University Grants Commission,New Delhi through the Major Research Project(F.No.40-28/2011(SR))
文摘Bilayered FTO/AZO （fluorine doped tin oxide/aluminium doped zinc oxide） films were fabricated using a simple, cost effective spray pyrolysis technique. X-ray diffraction （XRD） profiles of bilayered films showed that in the case of lower thickness FTO over layers, （002） plane of ZnO phase had the highest intensity, whereas the predominance was changed in favour of （200） plane of SnO2 phase for higher thickness FTO over layer. UV studies showed that bilayered FTO/AZO films exhibited a sharp absorption edge as that of AZO film. The decrease in the photoluminescence （PL） peak at 420 nm with increasing FTO over layer thickness indicated a reduction in the zinc vacancies which caused a reduction in the sheet resistance （Rsh）. Electrical studies revealed that, eventhough the Rsh value （916Ω/□） of bilayered FTO （313 nm）/AZO （314 nm） film was found to be higher than that of FTO single layer film （72Ω/□）, it was much lower than that of AZO single layer film （5661Ω/□））. The atomic force microscopy （AFM） images reflect the characteristic features of both zinc oxide and tin oxide films.
