The increasing demand in the diverse device applications of transparent conducting oxides （TCOs） requires synthesis of new TCOs of n- or p-type conductivity. This article is about materials engineering of ZnO-SnO2- ...The increasing demand in the diverse device applications of transparent conducting oxides （TCOs） requires synthesis of new TCOs of n- or p-type conductivity. This article is about materials engineering of ZnO-SnO2- In2O3-Ga2O3 to synthesize powders of the quaternary compound Zn2-xSn1-xlnxGaxO4-δ in the stoichiometry of x = 0.2, 0.3, and 0.4 by solid state reaction at 1275℃. Lattice parameters were determined by X-ray diffraction （XRD） technique and solubility of In3＋ and Ga3＋ in spinel Zn2SnO4 was found at 1275℃. The solubility limit of In3＋ and Ga3＋ in Zn2SnO4 is found at below x = 0.4. The optical transmittance approximated by the UV-Vis reflectance spectra showed excellent characteristics while optical band gap was consistent across 3.2 eV with slight decrease along increasing x value. Carrier mobility of the species was considerably higher than the older versions of zinc stannate spinel co-substitutions whereas the carrier concentrations were moderate.展开更多
Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency（RF） magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycry...Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency（RF） magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10^-4.cm,with a high Hall mobility of 30 cm^2.V-1.s-1 and a carrier concentration of 2.3×10^20 cm^-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.展开更多
The electronic structural, effective masses of carriers, and optical properties of pure and La-doped Cd2SnO4 are calculated by using the first-principles method based on the density functional theory. Using the GGA＋U...The electronic structural, effective masses of carriers, and optical properties of pure and La-doped Cd2SnO4 are calculated by using the first-principles method based on the density functional theory. Using the GGA＋U method, we show that Cd2SnO4 is a direct band-gap semiconductor with a band gap of 2.216 eV, the band gap decreases to 2.02 eV and the Fermi energy level moves to the conduction band after La doping. The density of states of Cd2SnO4 shows that the bottom of the conduction band is composed of Cd 5s, Sn 5s, and Sn 5p orbits, the top of the valence band is composed of Cd 4d and O 2p, and the La 5d orbital is hybridized with the O 2p orbital, which plays a key role at the conduction band bottom after La doping. The effective masses at the conduction band bottom of pure and La-doped Cd2SnO4 are 0.18m0 and 0.092m0, respectively, which indicates that the electrical conductivity of Cd2SnO4 after La doping is improved. The calculated optical properties show that the optical transmittance of La-doped Cd2SnO4 is 92%, the optical absorption edge is slightly blue shifted, and the optical band gap is increased to 3.263 eV. All the results indicate that the conductivity and optical transmittance of Cd2SnO4 can be improved by doping La.展开更多
Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency(RF) magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycryst...Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency(RF) magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10-4.cm,with a high Hall mobility of 30 cm2.V-1.s-1 and a carrier concentration of 2.3×1020 cm-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.展开更多
Transparent p-type conducting SnO2/Al/SnO2 multilayer films were fabricated on quartz substrates by radio frequency(RF) sputtering using SnO2 and Al targets. The deposited films were annealed at a fix temperature of 5...Transparent p-type conducting SnO2/Al/SnO2 multilayer films were fabricated on quartz substrates by radio frequency(RF) sputtering using SnO2 and Al targets. The deposited films were annealed at a fix temperature of 500 °C for different time durations(1-8 h). The effect of annealing time on the structural, morphological, optical and electrical performances of SnO2/Al/SnO2 multilayer films was studied. X-ray diffraction(XRD) results show that all the p-type conducting films possess polycrystalline SnO2 with tetragonal rutile structure. Hall-effect results indicate that 500 °C for 1 h is the optimum annealing condition for p-type SnO2/Al/SnO2 multilayer films, resulting in a hole concentration of 1.14×1018 cm-3 and a low resistivity of 1.38 ?·cm, respectively. The optical transmittance of the p-type SnO2/Al/SnO2 multilayer films is above 80% within annealing time range of 1-8 h, showing maximum for the films annealed for 1 h.展开更多
Ultrathin film-based transparent conductive oxides(TCOs)with a broad work function(WF)tunability are highly demanded for e cient energy conversion devices.However,reducing the film thickness below 50 nm is limited due...Ultrathin film-based transparent conductive oxides(TCOs)with a broad work function(WF)tunability are highly demanded for e cient energy conversion devices.However,reducing the film thickness below 50 nm is limited due to rapidly increasing resistance;furthermore,introducing dopants into TCOs such as indium tin oxide(ITO)to reduce the resistance decreases the transparency due to a trade-o between the two quantities.Herein,we demonstrate dopant-tunable ultrathin(≤50 nm)TCOs fabricated via electric field-driven metal implantation(m-TCOs;m=Ni,Ag,and Cu)without com-promising their innate electrical and optical properties.The m-TCOs exhibit a broad WF variation(0.97 eV),high transmittance in the UV to visible range(89–93%at 365 nm),and low sheet resistance(30–60Ωcm-2).Experimental and theoretical analyses show that interstitial metal atoms mainly a ect the change in the WF without substantial losses in optical transparency.The m-ITOs are employed as anode or cathode electrodes for organic light-emitting diodes(LEDs),inorganic UV LEDs,and organic photovoltaics for their universal use,leading to outstanding performances,even without hole injection layer for OLED through the WF-tailored Ni-ITO.These results verify the proposed m-TCOs enable e ective carrier transport and light extraction beyond the limits of traditional TCOs.展开更多
Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reacti ve magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films...Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reacti ve magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films have been investigated using optical spectroscopy, band structure analyses and ultraviolet photoelectro n spectroscopy (UPS). ZnO films have direct allowed transition band structure, w hich has been confirmed by the character of the optical absorption coefficient. The apparent band gap has been found directly proportional to N2/3, showing that the effect of Burstein-Moss shift on the band gap variations dominates over the many-body effect. With only standard cleaning protocols, the work function of ZnO: (Al, Mn) and ZnO: Al films have been measured to be 4.26 and 4.21eV, respec tively. The incorporation of Mn element into the matrix of ZnO, as a relatively deep donor, can remove some electrons from the conduction band and deplete the d ensity of occupied states at the Fermi energy, which causes a loss in measured p hotoemission intensity and an increase in the surface work function. Based on th e band gap and work function results, the energy band diagram of the ZnO: (Al, M n) film near its surface is also given.展开更多
Planar-structured amorphous InGaZnO(a-IGZO)film-based UV photodetectors with different ITO interdigitated electrode spacings were developed on flexible PI substrates via radio frequency magnetron sputtering and non-li...Planar-structured amorphous InGaZnO(a-IGZO)film-based UV photodetectors with different ITO interdigitated electrode spacings were developed on flexible PI substrates via radio frequency magnetron sputtering and non-lithographic fabrication processes.The effects of oxygen flow rate on the surface morphology,electrical transport,and chemical bonding properties of the a-IGZO films were systematically investigated to optimize the performance of the flexible detector.The average transmittance of the flexible a-IGZO photodetector is over 90%in the visible spectral range with a large photo-to-dark current ratio of 3.9×10^(3)under 360 nm UV illumination.The photocurrent of the detectors increases with decreasing the electrode spacing,which is attribute to formation of higher electrical field and drifting more electron-hole pairs to the electrode with shortening the electrode spacing.Under a UV illumination intensity of 9.1 mW/cm~2,the highest responsivity and detectivity of the photodetector with the electrode spacing of 0.4 mm reach 62.1 mA/W and2.83×10^(11)cm·Hz^(1/2)·W^(-1)at 11 V bias voltage,respectively.The flexible detector exhibits enhanced photoresponse performance with the rise and decay time of 2.02 and 0.94 s,respectively.These results can be used in a practical scheme to design and realize the a-IGZO based UV photodetectors with excellent transparency and flexibility for wearable UV monitoring applications.展开更多
Ta-doped SnO_(2)(TTO)is a suitable candidate to replace transparent conductive oxide(TCO)composed of expensive indium used for optoelectronics and silicon heterojunction solar cells fabricated below 200℃.However,TTO ...Ta-doped SnO_(2)(TTO)is a suitable candidate to replace transparent conductive oxide(TCO)composed of expensive indium used for optoelectronics and silicon heterojunction solar cells fabricated below 200℃.However,TTO films fabricated by sputtering at low temperature still demonstrate too high resistance and optical absorptance for application in industry.In this study,we investigate the influence of sputtering ambient on the optoelectrical properties of TTO films.The addition of hydrogen and oxygen to argon during sputtering leads to a large improvement in the optoelectrical properties of TTO films.The best TTO film has a low average absorptance of 1.9%and a low resistance of 3.8×10^(-3)Ω·cm with a high carrier density of 9.3×10^(19)cm^(-3)and mobility of 17.8 cm^(2)·V^(-1)·s^(-1).The micros tructural and compositional properties of TTO films were characterized using x-ray diffraction,x-ray photoelectron spectroscopy and UV-Vis spectrophotometry.A proper ratio of hydrogen to oxygen in the sputtering gas improves the crystallinity and the doping efficiency of Ta.Optical absorptance is also reduced with suppressed formation of Sn(Ⅱ)in the TTO films.Therefore,our findings exhibit remarkable potential for the industrial application of TTO as a low-cost TCO.展开更多
Transparent conductive oxide （TCO） thin film is a kind of functional material which has potential applications in solar cells and atomic oxygen （AO） resisting systems in spacecrafts. Of TCO, ZnO：Al （ZAO） and In...Transparent conductive oxide （TCO） thin film is a kind of functional material which has potential applications in solar cells and atomic oxygen （AO） resisting systems in spacecrafts. Of TCO, ZnO：Al （ZAO） and In2O3：Sn （ITO） thin films have been widely used and investigated. In this study, ZAO and ITO thin films were irradiated by AO with different amounts of fluence. The as-deposited samples and irradiated ones were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and Hall-effect measurement to investigate the dependence of the structure, morphology and electrical properties of ZAO or ITO on the amount of fluence of AO irradiation. It is noticed that AO has erosion effects on the surface of ZAO without evident influences upon its structure and conductive properties. Moreover, as the amount of AO fluence rises, the carrier concentration of ITO decreases causing the resistivity to increase by at most 21.7%.展开更多
Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of a...Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target. The dependence of the photoluminescence (PL) and transmittance properties of the AZO films deposited by cosputtering and sputtering on the AZO/ZnO target power ratio, R and the O2/Ar flow ratio, r were investigated, respectively. Only a deep level emission peak appears in the PL spectra of cosputtered AZO films whereas both UV emission and deep level emission peaks are observed in the PL spectra of sputtered AZO films. The absorption edges in the transmittance spectra of the AZO films shift to the lower wavelength region as R and r increase. Effects of crystallinity, surface roughness, PL on the transmittance of the AZO films were also explained using the X-ray diffraction (XRD), atomic force microscopy (AFM), and PL analysis results.展开更多
Aluminium doped tin oxide films have been deposited onto glass substrates by using a simplified and low cost spray pyrolysis technique. The AI doping level varies between 0 and 30 at.% in the step of 5 at.%. The resis...Aluminium doped tin oxide films have been deposited onto glass substrates by using a simplified and low cost spray pyrolysis technique. The AI doping level varies between 0 and 30 at.% in the step of 5 at.%. The resistivity （p） is the minimum （0.38 Ω cm） for 20 at.% of AI doping. The possible mechanism behind the phenomenal zig-zag variation in resistivity with respect to AI doping is discussed in detail. The nature of conductivity changes from n-type to p-type when the AI doping level is 10 at.%. The results show that 20 at.% is the optimum doping level for good quality p-type SnO2：AI films suitable for transparent electronic devices.展开更多
We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 in...We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent throughpore anodic aluminum oxide（AAO） membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 m A and 56% at 100 m A compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.展开更多
High transparent and conductive thin films of zinc doped tin oxide （ZTO） were deposited on quartz substrates by the radio-frequency （RF） magnetron sputtering using a 12 wt% ZnO doped with 88 wt% SnO2 ceramic targe...High transparent and conductive thin films of zinc doped tin oxide （ZTO） were deposited on quartz substrates by the radio-frequency （RF） magnetron sputtering using a 12 wt% ZnO doped with 88 wt% SnO2 ceramic target.The effect of substrate temperature on the structural,electrical and optical performances of ZTO films has been studied.X-ray diffraction （XRD） results show that ZTO films possess tetragonal rutile structure with the preferred orientation of （101）.The surface morphology and roughness of the films was investigated by the atomic force microscope （AFM）.The electrical characteristic （including carrier concentration,Hall mobility and resistivity） and optical transmittance were studied by the Hall tester and UV- VIS,respectively.The highest carrier concentration of -1.144×1020 cm-3 and the Hall mobility of 7.018 cm2（V ·sec）-1 for the film with an average transmittance of about 80.0% in the visible region and the lowest resistivity of 1.116×10-2 Ω·cm were obtained when the ZTO films deposited at 250 oC.展开更多
Transparent conducting oxides are increasingly important for optoelectronic and thin film transistor applications.La doped BaSnO_(3)is a strong candidate for its high transparency,high carrier concentration,high mobil...Transparent conducting oxides are increasingly important for optoelectronic and thin film transistor applications.La doped BaSnO_(3)is a strong candidate for its high transparency,high carrier concentration,high mobility and abundancy.However,due to the lack of lattice-matched substrates,the mobility of La:BaSnO_(3)remains inferior to single crystals.Here,by constructing a novel approach via delta doping La:BaSnO_(3)in a BaSnO_(3)/La:BaSnO_(3)/BaSnO_(3)(BSO/LBSO/BSO)heterostructure,we achieved room temperature mobility enhancement up to 110 cm^(2)·V^(−1)·s^(−1)while keeping the high carrier concentration at 5×10^(20)cm^(−3),reaching to the highest electrical conductivity in BaSnO_(3)based systems.The mobility is enhanced more than 100%compared to our La:BaSnO_(3)films,which is among the highest mobility in BaSnO_(3)based films and heterostructures.From atomic structural investigations,we found that both(1)the carrier confinement due to delta doping and(2)dislocation-free La:BaSnO_(3)conducting channel,revealed by atomic resolution scanning transmission electron microscopy(STEM)studies,are responsible for mobility enhancement.The enhanced mobility from heterostructure approach is widely applicable for transparent electrodes and high current thin film transistor applications.展开更多
Fluorine doped tin oxide SnO2：F thin films were prepared by the spray pyrolysis （SP） technique on glass substrates by using SnC12.2H2O as a precursor and NH4F and HF as doping compounds. A comparison between the pr...Fluorine doped tin oxide SnO2：F thin films were prepared by the spray pyrolysis （SP） technique on glass substrates by using SnC12.2H2O as a precursor and NH4F and HF as doping compounds. A comparison between the properties of the films obtained by using the two doping compounds was performed by using I-V characteristics in the dark at room temperature, AC measurements, and transmittance. It is found that the films prepared by using HF have smaller resistivity, lower impedance and they are less capacitive than films prepared by using NH4F. In addition, these films have higher transmittance, higher optical bandgap energy and narrower Urbach tail width. These results are interesting for the use of SnO2：F as forecontact in CdS/CdTe solar cells.展开更多
Fluorine doped tin oxide, SnO2:F, thin films were deposited by ultrasonic chemical spray starting from tin chloride and hydrofluoric acid. The physical characteristics of the films as a function of both water content ...Fluorine doped tin oxide, SnO2:F, thin films were deposited by ultrasonic chemical spray starting from tin chloride and hydrofluoric acid. The physical characteristics of the films as a function of both water content in the starting solution and substrate temperature were studied. The film structure was polycrystalline in all cases, showing that the intensity of (200) peak increased with the water content in the starting solution. The electrical resistivity decreased with the water content, reaching a minimum value, in the order of 8 × 10-4 Ωcm, for films deposited at 450℃ from a starting solution with a water content of 10 ml per 100 ml of solution;further increase in water content increased the corresponding resistivity. Optical transmittances of SnO2:F films were high, in the order of 75%, and the band gap values oscillated around 3.9 eV. SEM analysis showed uniform surface morphologies with different geometries depending on the deposition conditions. Composition analysis showed a stoichiometric compound with a [Sn/O] ratio around 1:2 in all samples. The presence of F into the SnO2 lattice was detected, within 2 at % respect to Sn.展开更多
Boron-doped zinc oxide transparent （BZO） films were prepared by sol-gel method. The effect of pyrolysis temperature on the crystallization behavior and properties was systematically investigated. XRD patterns reveal...Boron-doped zinc oxide transparent （BZO） films were prepared by sol-gel method. The effect of pyrolysis temperature on the crystallization behavior and properties was systematically investigated. XRD patterns revealed that the BZO films had wurtzite structure with a preferential growth orientation along the c-axis. With the increase of pyrolysis temperature, the particle size and surface roughness of the BZO films increased, suggesting that pyrolysis temperature is the critical factor for determining the crystallization behavior of the BZO films. Moreover, the carrier concentration and the carrier mobility increased with increasing the pyrolysis temperature, and the mean transmittance for every film is over 90% in the visible range.展开更多
Metasurfaces, two-dimensional equivalents of metamaterials, are engineered surfaces consisting of deep subwavelength features that have full control of the electromagnetic waves. Metasurfaces are not only being applie...Metasurfaces, two-dimensional equivalents of metamaterials, are engineered surfaces consisting of deep subwavelength features that have full control of the electromagnetic waves. Metasurfaces are not only being applied to the current de-vices throughout the electromagnetic spectrum from microwave to optics but also inspiring many new thrilling applica-tions such as programmable on-demand optics and photonics in future. In order to overcome the limits imposed by pas-sive metasurfaces, extensive researches have been put on utilizing different materials and mechanisms to design active metasurfaces. In this paper, we review the recent progress in tunable and reconfigurable metasurfaces and metadevicesthrough the different active materials deployed together with the different control mechanisms including electrical, ther-mal, optical, mechanical, and magnetic, and provide the perspective for their future development for applications.展开更多
TiO2/Au/TiO2 multilayer thin films were deposited at polymer substrate at room temperature using dc （direct current） magnetron sputtering method. By varying the thickness of each layer, the optical and electrical pr...TiO2/Au/TiO2 multilayer thin films were deposited at polymer substrate at room temperature using dc （direct current） magnetron sputtering method. By varying the thickness of each layer, the optical and electrical properties of the TiOz/Au/TiO2 multilayer films can be tailored to suit different applications. The thickness and optical properties of the Au layer and the quality of the Au-dielectric interfaces are critical for the electrical and optical performance of the Au-dielectric multilayer thin films. At the thickness of 8 rim, the Au layer forms a continuous structure having the lowest resistivity and it must be thin for high transmittance. The multilayer stack can be optimized to have a sheet resistance of 6 D./sq. at a transmittance over 80% at 680 nm in wavelength. The peak transmittance shifts towards the long wavelength region when the thickness of the two TiO2 （upper and lower） layers increases. When the film thickness of the two TiO2 film is 45 nm, a high transmittance value is obtained for the entire visible light wavelength region.展开更多
文摘The increasing demand in the diverse device applications of transparent conducting oxides （TCOs） requires synthesis of new TCOs of n- or p-type conductivity. This article is about materials engineering of ZnO-SnO2- In2O3-Ga2O3 to synthesize powders of the quaternary compound Zn2-xSn1-xlnxGaxO4-δ in the stoichiometry of x = 0.2, 0.3, and 0.4 by solid state reaction at 1275℃. Lattice parameters were determined by X-ray diffraction （XRD） technique and solubility of In3＋ and Ga3＋ in spinel Zn2SnO4 was found at 1275℃. The solubility limit of In3＋ and Ga3＋ in Zn2SnO4 is found at below x = 0.4. The optical transmittance approximated by the UV-Vis reflectance spectra showed excellent characteristics while optical band gap was consistent across 3.2 eV with slight decrease along increasing x value. Carrier mobility of the species was considerably higher than the older versions of zinc stannate spinel co-substitutions whereas the carrier concentrations were moderate.
基金Project supported by the Science Foundation of the Education Commission of Shandong Province,China (Grant No. J10LA04)
文摘Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency（RF） magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10^-4.cm,with a high Hall mobility of 30 cm^2.V-1.s-1 and a carrier concentration of 2.3×10^20 cm^-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.
文摘The electronic structural, effective masses of carriers, and optical properties of pure and La-doped Cd2SnO4 are calculated by using the first-principles method based on the density functional theory. Using the GGA＋U method, we show that Cd2SnO4 is a direct band-gap semiconductor with a band gap of 2.216 eV, the band gap decreases to 2.02 eV and the Fermi energy level moves to the conduction band after La doping. The density of states of Cd2SnO4 shows that the bottom of the conduction band is composed of Cd 5s, Sn 5s, and Sn 5p orbits, the top of the valence band is composed of Cd 4d and O 2p, and the La 5d orbital is hybridized with the O 2p orbital, which plays a key role at the conduction band bottom after La doping. The effective masses at the conduction band bottom of pure and La-doped Cd2SnO4 are 0.18m0 and 0.092m0, respectively, which indicates that the electrical conductivity of Cd2SnO4 after La doping is improved. The calculated optical properties show that the optical transmittance of La-doped Cd2SnO4 is 92%, the optical absorption edge is slightly blue shifted, and the optical band gap is increased to 3.263 eV. All the results indicate that the conductivity and optical transmittance of Cd2SnO4 can be improved by doping La.
基金Project supported by the Science Foundation of the Education Commission of Shandong Province,China (Grant No. J10LA04)
文摘Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency(RF) magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10-4.cm,with a high Hall mobility of 30 cm2.V-1.s-1 and a carrier concentration of 2.3×1020 cm-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.
基金Project(NIPA-2013-H0301-13-2009) supported by the MKE,Korea,under the ITRC support program supervised by the NIPAProject(2012HIB8A2026212) supported by the MEST and NRF through the Human Resource Training Project for Regional Innovation,Kored
文摘Transparent p-type conducting SnO2/Al/SnO2 multilayer films were fabricated on quartz substrates by radio frequency(RF) sputtering using SnO2 and Al targets. The deposited films were annealed at a fix temperature of 500 °C for different time durations(1-8 h). The effect of annealing time on the structural, morphological, optical and electrical performances of SnO2/Al/SnO2 multilayer films was studied. X-ray diffraction(XRD) results show that all the p-type conducting films possess polycrystalline SnO2 with tetragonal rutile structure. Hall-effect results indicate that 500 °C for 1 h is the optimum annealing condition for p-type SnO2/Al/SnO2 multilayer films, resulting in a hole concentration of 1.14×1018 cm-3 and a low resistivity of 1.38 ?·cm, respectively. The optical transmittance of the p-type SnO2/Al/SnO2 multilayer films is above 80% within annealing time range of 1-8 h, showing maximum for the films annealed for 1 h.
基金supported by a National Research Foundation of Korea(NRF)grant funded by the Korean government under Grant No.2016R1A3B1908249。
文摘Ultrathin film-based transparent conductive oxides(TCOs)with a broad work function(WF)tunability are highly demanded for e cient energy conversion devices.However,reducing the film thickness below 50 nm is limited due to rapidly increasing resistance;furthermore,introducing dopants into TCOs such as indium tin oxide(ITO)to reduce the resistance decreases the transparency due to a trade-o between the two quantities.Herein,we demonstrate dopant-tunable ultrathin(≤50 nm)TCOs fabricated via electric field-driven metal implantation(m-TCOs;m=Ni,Ag,and Cu)without com-promising their innate electrical and optical properties.The m-TCOs exhibit a broad WF variation(0.97 eV),high transmittance in the UV to visible range(89–93%at 365 nm),and low sheet resistance(30–60Ωcm-2).Experimental and theoretical analyses show that interstitial metal atoms mainly a ect the change in the WF without substantial losses in optical transparency.The m-ITOs are employed as anode or cathode electrodes for organic light-emitting diodes(LEDs),inorganic UV LEDs,and organic photovoltaics for their universal use,leading to outstanding performances,even without hole injection layer for OLED through the WF-tailored Ni-ITO.These results verify the proposed m-TCOs enable e ective carrier transport and light extraction beyond the limits of traditional TCOs.
基金This work was supported by the National Nalural Science Foundation of China(No.50172051).
文摘Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reacti ve magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films have been investigated using optical spectroscopy, band structure analyses and ultraviolet photoelectro n spectroscopy (UPS). ZnO films have direct allowed transition band structure, w hich has been confirmed by the character of the optical absorption coefficient. The apparent band gap has been found directly proportional to N2/3, showing that the effect of Burstein-Moss shift on the band gap variations dominates over the many-body effect. With only standard cleaning protocols, the work function of ZnO: (Al, Mn) and ZnO: Al films have been measured to be 4.26 and 4.21eV, respec tively. The incorporation of Mn element into the matrix of ZnO, as a relatively deep donor, can remove some electrons from the conduction band and deplete the d ensity of occupied states at the Fermi energy, which causes a loss in measured p hotoemission intensity and an increase in the surface work function. Based on th e band gap and work function results, the energy band diagram of the ZnO: (Al, M n) film near its surface is also given.
基金Funded by the Research Project of Shenzhen Science and Technology Innovation Committee(No.JCYJ20180306170801080)。
文摘Planar-structured amorphous InGaZnO(a-IGZO)film-based UV photodetectors with different ITO interdigitated electrode spacings were developed on flexible PI substrates via radio frequency magnetron sputtering and non-lithographic fabrication processes.The effects of oxygen flow rate on the surface morphology,electrical transport,and chemical bonding properties of the a-IGZO films were systematically investigated to optimize the performance of the flexible detector.The average transmittance of the flexible a-IGZO photodetector is over 90%in the visible spectral range with a large photo-to-dark current ratio of 3.9×10^(3)under 360 nm UV illumination.The photocurrent of the detectors increases with decreasing the electrode spacing,which is attribute to formation of higher electrical field and drifting more electron-hole pairs to the electrode with shortening the electrode spacing.Under a UV illumination intensity of 9.1 mW/cm~2,the highest responsivity and detectivity of the photodetector with the electrode spacing of 0.4 mm reach 62.1 mA/W and2.83×10^(11)cm·Hz^(1/2)·W^(-1)at 11 V bias voltage,respectively.The flexible detector exhibits enhanced photoresponse performance with the rise and decay time of 2.02 and 0.94 s,respectively.These results can be used in a practical scheme to design and realize the a-IGZO based UV photodetectors with excellent transparency and flexibility for wearable UV monitoring applications.
基金Project supported by the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2021B0101260001)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2019A1515110411)。
文摘Ta-doped SnO_(2)(TTO)is a suitable candidate to replace transparent conductive oxide(TCO)composed of expensive indium used for optoelectronics and silicon heterojunction solar cells fabricated below 200℃.However,TTO films fabricated by sputtering at low temperature still demonstrate too high resistance and optical absorptance for application in industry.In this study,we investigate the influence of sputtering ambient on the optoelectrical properties of TTO films.The addition of hydrogen and oxygen to argon during sputtering leads to a large improvement in the optoelectrical properties of TTO films.The best TTO film has a low average absorptance of 1.9%and a low resistance of 3.8×10^(-3)Ω·cm with a high carrier density of 9.3×10^(19)cm^(-3)and mobility of 17.8 cm^(2)·V^(-1)·s^(-1).The micros tructural and compositional properties of TTO films were characterized using x-ray diffraction,x-ray photoelectron spectroscopy and UV-Vis spectrophotometry.A proper ratio of hydrogen to oxygen in the sputtering gas improves the crystallinity and the doping efficiency of Ta.Optical absorptance is also reduced with suppressed formation of Sn(Ⅱ)in the TTO films.Therefore,our findings exhibit remarkable potential for the industrial application of TTO as a low-cost TCO.
基金National Natural Science Foundation of China (50471004)
文摘Transparent conductive oxide （TCO） thin film is a kind of functional material which has potential applications in solar cells and atomic oxygen （AO） resisting systems in spacecrafts. Of TCO, ZnO：Al （ZAO） and In2O3：Sn （ITO） thin films have been widely used and investigated. In this study, ZAO and ITO thin films were irradiated by AO with different amounts of fluence. The as-deposited samples and irradiated ones were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and Hall-effect measurement to investigate the dependence of the structure, morphology and electrical properties of ZAO or ITO on the amount of fluence of AO irradiation. It is noticed that AO has erosion effects on the surface of ZAO without evident influences upon its structure and conductive properties. Moreover, as the amount of AO fluence rises, the carrier concentration of ITO decreases causing the resistivity to increase by at most 21.7%.
文摘Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target. The dependence of the photoluminescence (PL) and transmittance properties of the AZO films deposited by cosputtering and sputtering on the AZO/ZnO target power ratio, R and the O2/Ar flow ratio, r were investigated, respectively. Only a deep level emission peak appears in the PL spectra of cosputtered AZO films whereas both UV emission and deep level emission peaks are observed in the PL spectra of sputtered AZO films. The absorption edges in the transmittance spectra of the AZO films shift to the lower wavelength region as R and r increase. Effects of crystallinity, surface roughness, PL on the transmittance of the AZO films were also explained using the X-ray diffraction (XRD), atomic force microscopy (AFM), and PL analysis results.
基金Financial support from the University Grants Commission ofIndia through the Major Research Project(F.No.40-28/2011(SR))the DST Grant(D.O.No.SR/S2/CMP-35/2004)
文摘Aluminium doped tin oxide films have been deposited onto glass substrates by using a simplified and low cost spray pyrolysis technique. The AI doping level varies between 0 and 30 at.% in the step of 5 at.%. The resistivity （p） is the minimum （0.38 Ω cm） for 20 at.% of AI doping. The possible mechanism behind the phenomenal zig-zag variation in resistivity with respect to AI doping is discussed in detail. The nature of conductivity changes from n-type to p-type when the AI doping level is 10 at.%. The results show that 20 at.% is the optimum doping level for good quality p-type SnO2：AI films suitable for transparent electronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61204049 and 51402366)Guangdong Natural Science Foundation,China(Grant No.S2012040007363)Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(Grant Nos.2012LYM 0058 and2013LYM 0022)
文摘We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent throughpore anodic aluminum oxide（AAO） membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 m A and 56% at 100 m A compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.
基金Funded by the Program for Changjiang Scholars and Innovative Research Team in University, Ministry of Education, China (No.IRT0547)
文摘High transparent and conductive thin films of zinc doped tin oxide （ZTO） were deposited on quartz substrates by the radio-frequency （RF） magnetron sputtering using a 12 wt% ZnO doped with 88 wt% SnO2 ceramic target.The effect of substrate temperature on the structural,electrical and optical performances of ZTO films has been studied.X-ray diffraction （XRD） results show that ZTO films possess tetragonal rutile structure with the preferred orientation of （101）.The surface morphology and roughness of the films was investigated by the atomic force microscope （AFM）.The electrical characteristic （including carrier concentration,Hall mobility and resistivity） and optical transmittance were studied by the Hall tester and UV- VIS,respectively.The highest carrier concentration of -1.144×1020 cm-3 and the Hall mobility of 7.018 cm2（V ·sec）-1 for the film with an average transmittance of about 80.0% in the visible region and the lowest resistivity of 1.116×10-2 Ω·cm were obtained when the ZTO films deposited at 250 oC.
基金supported by National Natural Science Foundation of China(Grant Nos.52172115)Nature Science Foundation of Guangdong Province,China(Grant Nos.2022A1515010762)+3 种基金supported by Shenzhen Science and Technology Program(Grant Nos.20231121093057002)Outstanding Talents Training Fund in Shenzhen(202106)supported by the Guangdong Provincial Key Laboratory Program(Grant No.2021B1212040001)Guangdong Basic and Applied Basic Research Foundation(Grant No.2023B1515130003)。
文摘Transparent conducting oxides are increasingly important for optoelectronic and thin film transistor applications.La doped BaSnO_(3)is a strong candidate for its high transparency,high carrier concentration,high mobility and abundancy.However,due to the lack of lattice-matched substrates,the mobility of La:BaSnO_(3)remains inferior to single crystals.Here,by constructing a novel approach via delta doping La:BaSnO_(3)in a BaSnO_(3)/La:BaSnO_(3)/BaSnO_(3)(BSO/LBSO/BSO)heterostructure,we achieved room temperature mobility enhancement up to 110 cm^(2)·V^(−1)·s^(−1)while keeping the high carrier concentration at 5×10^(20)cm^(−3),reaching to the highest electrical conductivity in BaSnO_(3)based systems.The mobility is enhanced more than 100%compared to our La:BaSnO_(3)films,which is among the highest mobility in BaSnO_(3)based films and heterostructures.From atomic structural investigations,we found that both(1)the carrier confinement due to delta doping and(2)dislocation-free La:BaSnO_(3)conducting channel,revealed by atomic resolution scanning transmission electron microscopy(STEM)studies,are responsible for mobility enhancement.The enhanced mobility from heterostructure approach is widely applicable for transparent electrodes and high current thin film transistor applications.
文摘Fluorine doped tin oxide SnO2：F thin films were prepared by the spray pyrolysis （SP） technique on glass substrates by using SnC12.2H2O as a precursor and NH4F and HF as doping compounds. A comparison between the properties of the films obtained by using the two doping compounds was performed by using I-V characteristics in the dark at room temperature, AC measurements, and transmittance. It is found that the films prepared by using HF have smaller resistivity, lower impedance and they are less capacitive than films prepared by using NH4F. In addition, these films have higher transmittance, higher optical bandgap energy and narrower Urbach tail width. These results are interesting for the use of SnO2：F as forecontact in CdS/CdTe solar cells.
基金This work was partially supported by CONACyT under contract Number 166601.
文摘Fluorine doped tin oxide, SnO2:F, thin films were deposited by ultrasonic chemical spray starting from tin chloride and hydrofluoric acid. The physical characteristics of the films as a function of both water content in the starting solution and substrate temperature were studied. The film structure was polycrystalline in all cases, showing that the intensity of (200) peak increased with the water content in the starting solution. The electrical resistivity decreased with the water content, reaching a minimum value, in the order of 8 × 10-4 Ωcm, for films deposited at 450℃ from a starting solution with a water content of 10 ml per 100 ml of solution;further increase in water content increased the corresponding resistivity. Optical transmittances of SnO2:F films were high, in the order of 75%, and the band gap values oscillated around 3.9 eV. SEM analysis showed uniform surface morphologies with different geometries depending on the deposition conditions. Composition analysis showed a stoichiometric compound with a [Sn/O] ratio around 1:2 in all samples. The presence of F into the SnO2 lattice was detected, within 2 at % respect to Sn.
文摘Boron-doped zinc oxide transparent （BZO） films were prepared by sol-gel method. The effect of pyrolysis temperature on the crystallization behavior and properties was systematically investigated. XRD patterns revealed that the BZO films had wurtzite structure with a preferential growth orientation along the c-axis. With the increase of pyrolysis temperature, the particle size and surface roughness of the BZO films increased, suggesting that pyrolysis temperature is the critical factor for determining the crystallization behavior of the BZO films. Moreover, the carrier concentration and the carrier mobility increased with increasing the pyrolysis temperature, and the mean transmittance for every film is over 90% in the visible range.
文摘Metasurfaces, two-dimensional equivalents of metamaterials, are engineered surfaces consisting of deep subwavelength features that have full control of the electromagnetic waves. Metasurfaces are not only being applied to the current de-vices throughout the electromagnetic spectrum from microwave to optics but also inspiring many new thrilling applica-tions such as programmable on-demand optics and photonics in future. In order to overcome the limits imposed by pas-sive metasurfaces, extensive researches have been put on utilizing different materials and mechanisms to design active metasurfaces. In this paper, we review the recent progress in tunable and reconfigurable metasurfaces and metadevicesthrough the different active materials deployed together with the different control mechanisms including electrical, ther-mal, optical, mechanical, and magnetic, and provide the perspective for their future development for applications.
文摘TiO2/Au/TiO2 multilayer thin films were deposited at polymer substrate at room temperature using dc （direct current） magnetron sputtering method. By varying the thickness of each layer, the optical and electrical properties of the TiOz/Au/TiO2 multilayer films can be tailored to suit different applications. The thickness and optical properties of the Au layer and the quality of the Au-dielectric interfaces are critical for the electrical and optical performance of the Au-dielectric multilayer thin films. At the thickness of 8 rim, the Au layer forms a continuous structure having the lowest resistivity and it must be thin for high transmittance. The multilayer stack can be optimized to have a sheet resistance of 6 D./sq. at a transmittance over 80% at 680 nm in wavelength. The peak transmittance shifts towards the long wavelength region when the thickness of the two TiO2 （upper and lower） layers increases. When the film thickness of the two TiO2 film is 45 nm, a high transmittance value is obtained for the entire visible light wavelength region.
