Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachm...Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachment and complex fabrication process introduce surface defects,compromising device stability and efficiency.In this work,we propose a solution-phase ligand exchange(SPLE)method utilizing inorganic ligands to develop stable p-type lead sulfide(PbS)CQD inks for the first time.Various amounts of tin(Ⅱ)iodide(SnI_(2))were mixed with lead halide(PbX_(2);X=I,Br)in the ligand solution.By precisely controlling the SnI_(2)concentration,we regulate the transition of PbS QDs from n-type to p-type.PbS CQDSCs were fabricated using two different HTL approaches:one with 1,2-ethanedithiol(EDT)-passivated QDs via the LbL method(control)and another with inorganic ligand-passivated QD ink(target).The target devices achieved a higher power conversion efficiency(PCE)of 10.93%,compared to 9.83%for the control devices.This improvement is attributed to reduced interfacial defects and enhanced carrier mobility.The proposed technique offers an efficient pathway for producing stable p-type PbS CQD inks using inorganic ligands,paving the way for high-performance and flexible CQD-based optoelectronic devices.展开更多
Realizing the high thermoelectric performance of p-type AgBiSe_(2)-based materials has been challenging due to their low p-type dopability.This work demonstrated that Cd doping at the Bi site converts n-type AgBiSe_(2...Realizing the high thermoelectric performance of p-type AgBiSe_(2)-based materials has been challenging due to their low p-type dopability.This work demonstrated that Cd doping at the Bi site converts n-type AgBiSe_(2) to p-type.The hole concentration is effectively increased with increasing Cd doping content,thereby enhancing the electrical conductivity.Theoretical calculations reveal that Cd doping flattens the edge of the valence band,resulting in an increase in the density-of-states effective mass and Seebeck coefficient.A record-high power factor of~6.2µW·cm^(−1)·K^(−2) was achieved at room temperature.Furthermore,the induced dislocations enhance the phonon scattering,contributing to the ultralow lattice thermal conductivity across the entire temperature range.As a result,a decent figure of merit(zT)of~0.3 at room temperature and a peak zT of~0.5 at 443 K were obtained in AgBi0.92Cd0.08Se_(2).Our work provides a feasible method for optimizing the thermoelectric performance of p-type AgBiSe_(2).展开更多
In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs)....In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs).The Ta-doped SnO_(x)(SnO_(x):Ta)film is deposited by radio-frequency(RF)magnetron sputtering with a Sn:Ta(3 at.%)target and thermally annealed at 270℃ for 30 min.Here,we observe that the SnO_(x):Ta film presents increased crystallinity,reduced defect density(3.25×10^(12)cm^(−2)·eV^(−1)),and widened bandgap(1.98 eV),in comparison with the undoped SnO_(x)film.As a result,the SnO_(x):Ta TFTs exhibit a lower off-state current(Ioff),an improved on/off current ratio(2.17×10^(4)),a remarkably decreased subthreshold swing(SS)by 41%,and enhanced device stability.Additionally,by introducing Ta dopants,the fringe effect as well as the impact of channel width-to-length ratio(W/L)on electrical performances of the p-type oxide TFTs can be effectively suppressed.These results shall contribute to further exploration and development of p-type SnO_(x)TFTs.展开更多
P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relativ...P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relatively low TE performance,limiting their application in TE devices.In this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.As a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.Meanwhile,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.The synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the TE performance of Zintl phase materials or even others.展开更多
The lattice-matched XBn structures of InAsSb,grown on GaSb substrates,exhibit high crystal quali⁃ty,and can achieve extremely low dark currents at high operating temperatures(HOT).Its superior performance is attribute...The lattice-matched XBn structures of InAsSb,grown on GaSb substrates,exhibit high crystal quali⁃ty,and can achieve extremely low dark currents at high operating temperatures(HOT).Its superior performance is attributed to the unipolar barrier,which blocks the majority carriers while allowing unhindered hole transport.To further explore the energy band and carrier transport mechanisms of the XBn unipolar barrier structure,this pa⁃per systematically investigates the influence of doping on the dark current,photocurrent,and tunneling character⁃istics of InAsSb photodetectors in the PBn structure.Three high-quality InAsSb samples with unintentionally doped absorption layers(AL)were prepared,with varying p-type doping concentrations in the GaSb contact layer(CL)and the AlAsSb barrier layer(BL).As the p-type doping concentration in the CL increased,the device’s turn-on bias voltage also increased,and p-type doping in the BL led to tunneling occurring at lower bias voltages.For the sample with UID BL,which exhibited an extremely low dark current of 5×10^(-6) A/cm^(2).The photocurrent characteristics were well-fitted using the back-to-back diode model,revealing the presence of two opposing space charge regions on either side of the BL.展开更多
Advancing high-voltage stability of layered sodium-ion oxides represents a pivotal avenue for their progress in energy storage applications.Despite this,a comprehensive understanding of the mechanisms underpinning the...Advancing high-voltage stability of layered sodium-ion oxides represents a pivotal avenue for their progress in energy storage applications.Despite this,a comprehensive understanding of the mechanisms underpinning their structural deterioration at elevated voltages remains insufficiently explored.In this study,we unveil a layer delamination phenomenon of Na_(0.67)Ni_(0.3)Mn_(0.7)O_(2)(NNM)within the 2.0-4.3 V voltage,attributed to considerable volumetric fluctuations along the c-axis and lattice oxygen reactions induced by the simultaneous Ni^(3+)/Ni^(4+)and anion redox reactions.By introducing Mg doping to diminished Ni-O antibonding,the anion oxidation-reduction reactions are effectively mitigated,and the structural integrity of the P2 phase remains firmly intact,safeguarding active sites and precluding the formation of novel interfaces.The Na_(0.67)Mg_(0.05)Ni_(0.25)Mn_(0.7)O_(2)(NMNM-5)exhibits a specific capacity of100.7 mA h g^(-1),signifying an 83%improvement compared to the NNM material within the voltage of2.0-4.3 V.This investigation underscores the intricate interplay between high-voltage stability and structural degradation mechanisms in layered sodium-ion oxides.展开更多
The P-type plasma membrane(PM)H^(+)-ATPases(HAs)are crucial for plant development,growth,and defense.The HAs have been thoroughly characterized in many different plants.However,despite their importance,the functions o...The P-type plasma membrane(PM)H^(+)-ATPases(HAs)are crucial for plant development,growth,and defense.The HAs have been thoroughly characterized in many different plants.However,despite their importance,the functions of HAs in germination and seed dormancy(SD)have not been validated in wheat.Here,we identified 28 TaHA genes(TaHA1-28)in common wheat,which were divided into five subfamilies.An examination of gene expression in strong-and weak-SD wheat varieties led to the discovery of six candidate genes(TaHA7/-12/-14/-16/-18/-20).Based on a single nucleotide polymorphism(SNP)mutation(C/T)in the TaHA7 coding region,a CAPS marker(HA7)was developed and validated in 168 wheat varieties and 171 Chinese mini-core collections that exhibit diverse germination and SD phenotypes.We further verified the roles of the two allelic variations of TaHA7 in germination and SD using wheat mutants mutagenized with ethyl methane sulphonate(EMS)in‘Jimai 22’and‘Jing 411’backgrounds,and in transgenic Arabidopsis lines.TaHA7 appears to regulate germination and SD by mediating gibberellic acid(GA)and abscisic acid(ABA)signaling,metabolism,and biosynthesis.The results presented here will enable future research regarding the TaHAs in wheat.展开更多
Raman spectra of undoped GaN and Mg-doped GaN films grown by metal-organic chemical-vapor deposition on sapphire are investigated between 78 and 573K.A peak at 247cm -1 is observed in both Raman spectra of GaN and Mg-...Raman spectra of undoped GaN and Mg-doped GaN films grown by metal-organic chemical-vapor deposition on sapphire are investigated between 78 and 573K.A peak at 247cm -1 is observed in both Raman spectra of GaN and Mg-doped GaN.It is suggested that the defect-induced scattering is origin of the mode.The electronic Raman scattering mechanism and Mg-related local vibrational mode are excluded.Furthermore,the differences of E_2 and A_1(LO) modes in two samples are also discussed.The stress relaxation is observed in Mg-doped GaN.展开更多
SnSe crystals have been discovered as one of the most efficient thermoelectric materials due to their remarkable thermal and electrical transports. But the polycrystalline SnSe possesses much lower performance especia...SnSe crystals have been discovered as one of the most efficient thermoelectric materials due to their remarkable thermal and electrical transports. But the polycrystalline SnSe possesses much lower performance especially for the low carrier mobility and electrical conductivity. We firstly attempted to explain and verify the difference in the electrical conductivity as a function of temperature between p-type crystalline and polycrystalline SnSe by considering the grain boundary effects in the polycrystalline samples. On the basis of 2% Na doping to optimize the carrier concentration, the carrier mobility is improved by further introducing In, leading to enhanced carrier mobility from 3 to 9 cm2·V^(-1)·s^(-1) in polycrystalline SnSe. Moreover, In doping introduces extra resonant levels in SnSe, which increases the density of states near Fermi level and leads to an enhanced band effective mass. Large Seebeck coefficient of ~205 l V·K^(-1) at 300 K and maximum power factor of ~7.5 l W·cm^(-1)·K^(-2) at 773 K can be obtained in the Sn_(0.975)Na_(0.02)In_(0.005) Se sample,leading to a competitively high dimensionless figure of merit(ZT) value exceeding 1.1 at 773 K.展开更多
A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type sem...A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations （DFT） and electrochem ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat alytic hydrogen production experiments under a visible light irradiation （A〉420 nm） were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.展开更多
Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ℃ using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods ar...Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ℃ using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 ℃-250 ℃. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 ℃, whereas, it behaves as a p-type semiconductor below 50 ℃. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods.展开更多
The ultralow detection threshold,ultralow intrinsic background,and excellent energy resolution of ptype point-contact germanium detectors are important for rare-event searches,in particular for the detection of direct...The ultralow detection threshold,ultralow intrinsic background,and excellent energy resolution of ptype point-contact germanium detectors are important for rare-event searches,in particular for the detection of direct dark matter interactions,coherent elastic neutrino-nucleus scattering,and neutrinoless double beta decay.Anomalous bulk events with an extremely fast rise time are observed in the CDEX-1B detector.We report a method of extracting fast bulk events from bulk events using a pulse shape simulation and reconstructed source experiment signature.Calibration data and the distribution of X-rays generated by intrinsic radioactivity verified that the fast bulk experienced a single hit near the passivation layer.The performance of this germanium detector indicates that it is capable of single-hit bulk spatial resolution and thus provides a background removal technique.展开更多
The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,...The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,the intrinsically p-type Mg3Sb2 shows low figure of merit（z T = 0.23 at 723 K） for its poor electrical conductivity.In this study,a series of Mg（3-x）LixSb2 bulk materials have been prepared by high-energy ball milling and spark plasma sintering（SPS） process.Electrical transport measurements on these materials revealed significant improvement on the power factor with respect to the undoped sample,which can be essentially attributed to the increased carrier concentration,leading to a maximum z T of0.59 at 723 K with the optimum doping level x = 0.01.Additionally,the engineering z T and energy conversion efficiency are calculated to be 0.235 and 4.89%,respectively.To our best knowledge,those are the highest values of all reported p-type Mg3Sb2-based compounds with single element doping.展开更多
AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory ...AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory quantum efficiency.The utilization of polarization-doped technique by grading the Al content in p-type layer has demonstrated its effectiveness in improving LED performances by providing sufficiently high hole concentration. However, too large degree of grading through monotonously increasing the Al content causes strains in active regions, which constrains application of this technique, especially for short wavelength UV-LEDs. To further improve 340-nm UV-LED performances, segmentally graded Al content p-Al_xGa_(1-x)N has been proposed and investigated in this work. Numerical results show that the internal quantum efficiency and output power of proposed structures are improved due to the enhanced carrier concentrations and radiative recombination rate in multiple quantum wells, compared to those of the conventional UV-LED with a stationary Al content AlGaN electron blocking layer. Moreover, by adopting the segmentally graded p-Al_xGa_(1-x)N, band bending within the last quantum barrier/p-type layer interface is effectively eliminated.展开更多
Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2 [Diethylzinc, DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and...Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2 [Diethylzinc, DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·cm with a hole concentration of 3.71×1017 cm-3. Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is a p-type semiconductor.展开更多
Zinc oxide（ZnO） is a compound semiconductor with a direct band gap and high exciton binding energy.The unique property,i.e.,high efficient light emission at ultraviolet band,makes ZnO potentially applied to the shor...Zinc oxide（ZnO） is a compound semiconductor with a direct band gap and high exciton binding energy.The unique property,i.e.,high efficient light emission at ultraviolet band,makes ZnO potentially applied to the short-wavelength light emitting devices.However,efficient p-type doping is extremely hard for ZnO.Due to the wide band gap and low valence band energy,the self-compensation from donors and high ionization energy of acceptors are the two main problems hindering the enhancement of free hole concentration.Native defects in ZnO can be divided into donor-like and acceptorlike ones.The self-compensation has been found mainly to originate from zinc interstitial and oxygen vacancy related donors.While the acceptor-like defect,zinc vacancy,is thought to be linked to complex shallow acceptors in group-VA doped ZnO.Therefore,the understanding of the behaviors of the native defects is critical to the realization of high-efficient p-type conduction.Meanwhile,some novel ideas have been extensively proposed,like double-acceptor co-doping,acceptor doping in iso-valent element alloyed ZnO,etc.,and have opened new directions for p-type doping.Some of the approaches have been positively judged.In this article,we thus review the recent（2011-now） research progress of the native defects and p-type doping approaches globally.We hope to provide a comprehensive overview and describe a complete picture of the research status of the p-type doping in ZnO for the reference of the researchers in a similar area.展开更多
Li-doped p-type ZnO ceramics were prepared by conventional methods according to the chemical formula Zn1-xLixO2 where x=0.5, 1.0, 1.5 and 2.0 mole fraction, respectively. The crystal structures of the prepared samples...Li-doped p-type ZnO ceramics were prepared by conventional methods according to the chemical formula Zn1-xLixO2 where x=0.5, 1.0, 1.5 and 2.0 mole fraction, respectively. The crystal structures of the prepared samples were studied by X-ray diffraction analysis. The dielectric properties （including dielectric constant ε′ and dielectric loss ε″） and dc-electrical conductivity [σ（Ω^-1.cm^-1）] were investigated. The dielectric constant ε′ was sharply decreased at the low frequency range and independent on frequency at high frequency range. Otherwise, the dielectric loss ε″ varied with frequency and showed absorption peak located from 200 Hz to 4 kHz and moved to higher frequency as the concentration of Li＋ doped increased. It was found that dcelectrical conductivity logσ varied from -9 to -5 and the energy gap width were calculated by using Arrhenius equation. The p-type conductivity of Li-doped ZnO may be attributed to the formation of a Lizn-Lii donor complex, which is limited by reducing the amount of Lii.展开更多
Zinc oxide （ZnO） is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications, such as the flat panel displays and solar cells used in sports tournament. Despite ...Zinc oxide （ZnO） is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications, such as the flat panel displays and solar cells used in sports tournament. Despite its advantages, the application of ZnO is hampered by the lack of stable p-type doping. In this paper, the recent progress in this field was briefly reviewed, and a comprehensive summary of the research was carded out on ZnO fabrication methods and its electrical, optical, and magnetic properties were presented.展开更多
基金supported by MEXT KAKENHI Grant(24K01295,26286013).
文摘Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachment and complex fabrication process introduce surface defects,compromising device stability and efficiency.In this work,we propose a solution-phase ligand exchange(SPLE)method utilizing inorganic ligands to develop stable p-type lead sulfide(PbS)CQD inks for the first time.Various amounts of tin(Ⅱ)iodide(SnI_(2))were mixed with lead halide(PbX_(2);X=I,Br)in the ligand solution.By precisely controlling the SnI_(2)concentration,we regulate the transition of PbS QDs from n-type to p-type.PbS CQDSCs were fabricated using two different HTL approaches:one with 1,2-ethanedithiol(EDT)-passivated QDs via the LbL method(control)and another with inorganic ligand-passivated QD ink(target).The target devices achieved a higher power conversion efficiency(PCE)of 10.93%,compared to 9.83%for the control devices.This improvement is attributed to reduced interfacial defects and enhanced carrier mobility.The proposed technique offers an efficient pathway for producing stable p-type PbS CQD inks using inorganic ligands,paving the way for high-performance and flexible CQD-based optoelectronic devices.
基金supported by the Fundamental Research Funds for the Central Universities(No.G2022WD01007)the Natural Science Foundation of Shaanxi Province(No.2023-JC-QN-0380)+2 种基金Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515111200 and 2021A1515111155)Nantong Natural Science Foundation(No.JC2023080)the Basic Research Programs of Taicang(Nos.TC2022JC08 and TC2023JC03).
文摘Realizing the high thermoelectric performance of p-type AgBiSe_(2)-based materials has been challenging due to their low p-type dopability.This work demonstrated that Cd doping at the Bi site converts n-type AgBiSe_(2) to p-type.The hole concentration is effectively increased with increasing Cd doping content,thereby enhancing the electrical conductivity.Theoretical calculations reveal that Cd doping flattens the edge of the valence band,resulting in an increase in the density-of-states effective mass and Seebeck coefficient.A record-high power factor of~6.2µW·cm^(−1)·K^(−2) was achieved at room temperature.Furthermore,the induced dislocations enhance the phonon scattering,contributing to the ultralow lattice thermal conductivity across the entire temperature range.As a result,a decent figure of merit(zT)of~0.3 at room temperature and a peak zT of~0.5 at 443 K were obtained in AgBi0.92Cd0.08Se_(2).Our work provides a feasible method for optimizing the thermoelectric performance of p-type AgBiSe_(2).
基金supported in part by National Key R&D Program of China(Grant No.2022YFE0141500)National Natural Science Foundation of China(Grant Nos.62004065 and 62274059).
文摘In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs).The Ta-doped SnO_(x)(SnO_(x):Ta)film is deposited by radio-frequency(RF)magnetron sputtering with a Sn:Ta(3 at.%)target and thermally annealed at 270℃ for 30 min.Here,we observe that the SnO_(x):Ta film presents increased crystallinity,reduced defect density(3.25×10^(12)cm^(−2)·eV^(−1)),and widened bandgap(1.98 eV),in comparison with the undoped SnO_(x)film.As a result,the SnO_(x):Ta TFTs exhibit a lower off-state current(Ioff),an improved on/off current ratio(2.17×10^(4)),a remarkably decreased subthreshold swing(SS)by 41%,and enhanced device stability.Additionally,by introducing Ta dopants,the fringe effect as well as the impact of channel width-to-length ratio(W/L)on electrical performances of the p-type oxide TFTs can be effectively suppressed.These results shall contribute to further exploration and development of p-type SnO_(x)TFTs.
基金supported by the National Natural Science Foundation of China(Grant Nos.U21A2054,52273285,52061009,52262032)the National Key Research and Development Program of China(No.2022YFE0119100)the Guangxi Science and Technology Planning Project(Grant No.AD21220056).
文摘P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relatively low TE performance,limiting their application in TE devices.In this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.As a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.Meanwhile,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.The synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the TE performance of Zintl phase materials or even others.
基金Supported by the Candidate Talents Training Fund of Yunnan Province(202205AC160054)the National Natural Science Foundation of China(62174156)。
文摘The lattice-matched XBn structures of InAsSb,grown on GaSb substrates,exhibit high crystal quali⁃ty,and can achieve extremely low dark currents at high operating temperatures(HOT).Its superior performance is attributed to the unipolar barrier,which blocks the majority carriers while allowing unhindered hole transport.To further explore the energy band and carrier transport mechanisms of the XBn unipolar barrier structure,this pa⁃per systematically investigates the influence of doping on the dark current,photocurrent,and tunneling character⁃istics of InAsSb photodetectors in the PBn structure.Three high-quality InAsSb samples with unintentionally doped absorption layers(AL)were prepared,with varying p-type doping concentrations in the GaSb contact layer(CL)and the AlAsSb barrier layer(BL).As the p-type doping concentration in the CL increased,the device’s turn-on bias voltage also increased,and p-type doping in the BL led to tunneling occurring at lower bias voltages.For the sample with UID BL,which exhibited an extremely low dark current of 5×10^(-6) A/cm^(2).The photocurrent characteristics were well-fitted using the back-to-back diode model,revealing the presence of two opposing space charge regions on either side of the BL.
基金the financial support from the National Natural Science Foundation of China(52202338)。
文摘Advancing high-voltage stability of layered sodium-ion oxides represents a pivotal avenue for their progress in energy storage applications.Despite this,a comprehensive understanding of the mechanisms underpinning their structural deterioration at elevated voltages remains insufficiently explored.In this study,we unveil a layer delamination phenomenon of Na_(0.67)Ni_(0.3)Mn_(0.7)O_(2)(NNM)within the 2.0-4.3 V voltage,attributed to considerable volumetric fluctuations along the c-axis and lattice oxygen reactions induced by the simultaneous Ni^(3+)/Ni^(4+)and anion redox reactions.By introducing Mg doping to diminished Ni-O antibonding,the anion oxidation-reduction reactions are effectively mitigated,and the structural integrity of the P2 phase remains firmly intact,safeguarding active sites and precluding the formation of novel interfaces.The Na_(0.67)Mg_(0.05)Ni_(0.25)Mn_(0.7)O_(2)(NMNM-5)exhibits a specific capacity of100.7 mA h g^(-1),signifying an 83%improvement compared to the NNM material within the voltage of2.0-4.3 V.This investigation underscores the intricate interplay between high-voltage stability and structural degradation mechanisms in layered sodium-ion oxides.
基金supported by grants from the University Synergy Innovation Program of Anhui Province,China(GXXT-2021-058)the National Natural Science Foundation of China(U20A2033)+4 种基金the Natural Science Foundation of Anhui Province,China(2108085MC98)the Key Scientific and Technological Breakthroughs of Anhui Province,China(2021d06050003)the Anhui Province Education Department Sciences Research Project,China(YJS20210212)the Scientific Research Project of Higher Education in Anhui Province,China(2022AH050924 and 2022AH050885)the Jiangsu Collaborative Innovation Center for Modern Crop Production,China(JCIC-MCP)。
文摘The P-type plasma membrane(PM)H^(+)-ATPases(HAs)are crucial for plant development,growth,and defense.The HAs have been thoroughly characterized in many different plants.However,despite their importance,the functions of HAs in germination and seed dormancy(SD)have not been validated in wheat.Here,we identified 28 TaHA genes(TaHA1-28)in common wheat,which were divided into five subfamilies.An examination of gene expression in strong-and weak-SD wheat varieties led to the discovery of six candidate genes(TaHA7/-12/-14/-16/-18/-20).Based on a single nucleotide polymorphism(SNP)mutation(C/T)in the TaHA7 coding region,a CAPS marker(HA7)was developed and validated in 168 wheat varieties and 171 Chinese mini-core collections that exhibit diverse germination and SD phenotypes.We further verified the roles of the two allelic variations of TaHA7 in germination and SD using wheat mutants mutagenized with ethyl methane sulphonate(EMS)in‘Jimai 22’and‘Jing 411’backgrounds,and in transgenic Arabidopsis lines.TaHA7 appears to regulate germination and SD by mediating gibberellic acid(GA)and abscisic acid(ABA)signaling,metabolism,and biosynthesis.The results presented here will enable future research regarding the TaHAs in wheat.
文摘Raman spectra of undoped GaN and Mg-doped GaN films grown by metal-organic chemical-vapor deposition on sapphire are investigated between 78 and 573K.A peak at 247cm -1 is observed in both Raman spectra of GaN and Mg-doped GaN.It is suggested that the defect-induced scattering is origin of the mode.The electronic Raman scattering mechanism and Mg-related local vibrational mode are excluded.Furthermore,the differences of E_2 and A_1(LO) modes in two samples are also discussed.The stress relaxation is observed in Mg-doped GaN.
基金financially supported by the National Key Research and Development Program of China (Nos.2018YFA0702100 and 2018YFB0703600)the National Natural Science Foundation of China (Nos.51772012 and 51671015)+3 种基金Beijing Natural Science Foundation (No.JQ18004)National Postdoctoral Program for Innovative Talents (No.BX20200028)the support from the National Science Fund for Distinguished Young Scholars (No.51925101)the high performance computing (HPC) resources at Beihang University。
文摘SnSe crystals have been discovered as one of the most efficient thermoelectric materials due to their remarkable thermal and electrical transports. But the polycrystalline SnSe possesses much lower performance especially for the low carrier mobility and electrical conductivity. We firstly attempted to explain and verify the difference in the electrical conductivity as a function of temperature between p-type crystalline and polycrystalline SnSe by considering the grain boundary effects in the polycrystalline samples. On the basis of 2% Na doping to optimize the carrier concentration, the carrier mobility is improved by further introducing In, leading to enhanced carrier mobility from 3 to 9 cm2·V^(-1)·s^(-1) in polycrystalline SnSe. Moreover, In doping introduces extra resonant levels in SnSe, which increases the density of states near Fermi level and leads to an enhanced band effective mass. Large Seebeck coefficient of ~205 l V·K^(-1) at 300 K and maximum power factor of ~7.5 l W·cm^(-1)·K^(-2) at 773 K can be obtained in the Sn_(0.975)Na_(0.02)In_(0.005) Se sample,leading to a competitively high dimensionless figure of merit(ZT) value exceeding 1.1 at 773 K.
基金financially supported by the National Natural Science Foundation of China(Grant No.21090341 and 21361140346)the National Basic Research Program(973 Program)of the Ministry of Science and Technology of China(Grant No.2014CB239401)
文摘A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations （DFT） and electrochem ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat alytic hydrogen production experiments under a visible light irradiation （A〉420 nm） were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60771019,61271070,and 61274074)the Tianjin Key Research Program of Application Foundation and Advanced Technology,China(Grant No.11JCZDJC15300)
文摘Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ℃ using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 ℃-250 ℃. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 ℃, whereas, it behaves as a p-type semiconductor below 50 ℃. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods.
基金supported by the National Key Research and Development Program of China(No.2017YFA0402203)the National Natural Science Foundation of China(No.11975162)the SPARK project of the research and innovation program of Sichuan University(No.2018SCUH0051)。
文摘The ultralow detection threshold,ultralow intrinsic background,and excellent energy resolution of ptype point-contact germanium detectors are important for rare-event searches,in particular for the detection of direct dark matter interactions,coherent elastic neutrino-nucleus scattering,and neutrinoless double beta decay.Anomalous bulk events with an extremely fast rise time are observed in the CDEX-1B detector.We report a method of extracting fast bulk events from bulk events using a pulse shape simulation and reconstructed source experiment signature.Calibration data and the distribution of X-rays generated by intrinsic radioactivity verified that the fast bulk experienced a single hit near the passivation layer.The performance of this germanium detector indicates that it is capable of single-hit bulk spatial resolution and thus provides a background removal technique.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1601213 and 51572287)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH013)
文摘The Zintl compound Mg3Sb2 has been recently identified as promising thermoelectric material owing to its high thermoelectric performance and cost-effective,nontoxicity and environment friendly characteristics.However,the intrinsically p-type Mg3Sb2 shows low figure of merit（z T = 0.23 at 723 K） for its poor electrical conductivity.In this study,a series of Mg（3-x）LixSb2 bulk materials have been prepared by high-energy ball milling and spark plasma sintering（SPS） process.Electrical transport measurements on these materials revealed significant improvement on the power factor with respect to the undoped sample,which can be essentially attributed to the increased carrier concentration,leading to a maximum z T of0.59 at 723 K with the optimum doping level x = 0.01.Additionally,the engineering z T and energy conversion efficiency are calculated to be 0.235 and 4.89%,respectively.To our best knowledge,those are the highest values of all reported p-type Mg3Sb2-based compounds with single element doping.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61874161 and 11474105)the Science and Technology Program of Guangdong Province,China(Grant Nos.2017B010127001 and 2015B010105011)+4 种基金the Education Department Project of Guangdong Province,China(Grant No.2017KZDXM022)the Science and Technology Project of Guangzhou City,China(Grant No.201607010246)the Program for Changjiang Scholars and Innovative Research Team in Universities of China(Grant No.IRT13064)the Science and Technology Project of Shenzhen City,China(Grant No.GJHZ20180416164721073)the Science and Technology Planning of Guangdong Province,China(Grant No.2015B010112002)
文摘AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory quantum efficiency.The utilization of polarization-doped technique by grading the Al content in p-type layer has demonstrated its effectiveness in improving LED performances by providing sufficiently high hole concentration. However, too large degree of grading through monotonously increasing the Al content causes strains in active regions, which constrains application of this technique, especially for short wavelength UV-LEDs. To further improve 340-nm UV-LED performances, segmentally graded Al content p-Al_xGa_(1-x)N has been proposed and investigated in this work. Numerical results show that the internal quantum efficiency and output power of proposed structures are improved due to the enhanced carrier concentrations and radiative recombination rate in multiple quantum wells, compared to those of the conventional UV-LED with a stationary Al content AlGaN electron blocking layer. Moreover, by adopting the segmentally graded p-Al_xGa_(1-x)N, band bending within the last quantum barrier/p-type layer interface is effectively eliminated.
文摘Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2 [Diethylzinc, DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·cm with a hole concentration of 3.71×1017 cm-3. Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is a p-type semiconductor.
基金Project supported by the State Key Program for Basic Research of China(Grant No.2011CB302003)the National Natural Science Foundation of China(Grant Nos.61274058,61322403,61504057,and 61574075)+1 种基金the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20130013 and BK20150585)the Six Talent Peaks Project in Jiangsu Province,China(Grant No.2014XXRJ001)
文摘Zinc oxide（ZnO） is a compound semiconductor with a direct band gap and high exciton binding energy.The unique property,i.e.,high efficient light emission at ultraviolet band,makes ZnO potentially applied to the short-wavelength light emitting devices.However,efficient p-type doping is extremely hard for ZnO.Due to the wide band gap and low valence band energy,the self-compensation from donors and high ionization energy of acceptors are the two main problems hindering the enhancement of free hole concentration.Native defects in ZnO can be divided into donor-like and acceptorlike ones.The self-compensation has been found mainly to originate from zinc interstitial and oxygen vacancy related donors.While the acceptor-like defect,zinc vacancy,is thought to be linked to complex shallow acceptors in group-VA doped ZnO.Therefore,the understanding of the behaviors of the native defects is critical to the realization of high-efficient p-type conduction.Meanwhile,some novel ideas have been extensively proposed,like double-acceptor co-doping,acceptor doping in iso-valent element alloyed ZnO,etc.,and have opened new directions for p-type doping.Some of the approaches have been positively judged.In this article,we thus review the recent（2011-now） research progress of the native defects and p-type doping approaches globally.We hope to provide a comprehensive overview and describe a complete picture of the research status of the p-type doping in ZnO for the reference of the researchers in a similar area.
文摘Li-doped p-type ZnO ceramics were prepared by conventional methods according to the chemical formula Zn1-xLixO2 where x=0.5, 1.0, 1.5 and 2.0 mole fraction, respectively. The crystal structures of the prepared samples were studied by X-ray diffraction analysis. The dielectric properties （including dielectric constant ε′ and dielectric loss ε″） and dc-electrical conductivity [σ（Ω^-1.cm^-1）] were investigated. The dielectric constant ε′ was sharply decreased at the low frequency range and independent on frequency at high frequency range. Otherwise, the dielectric loss ε″ varied with frequency and showed absorption peak located from 200 Hz to 4 kHz and moved to higher frequency as the concentration of Li＋ doped increased. It was found that dcelectrical conductivity logσ varied from -9 to -5 and the energy gap width were calculated by using Arrhenius equation. The p-type conductivity of Li-doped ZnO may be attributed to the formation of a Lizn-Lii donor complex, which is limited by reducing the amount of Lii.
基金Funded by the National Social Science Fund Project(No.2012BTY014)
文摘Zinc oxide （ZnO） is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications, such as the flat panel displays and solar cells used in sports tournament. Despite its advantages, the application of ZnO is hampered by the lack of stable p-type doping. In this paper, the recent progress in this field was briefly reviewed, and a comprehensive summary of the research was carded out on ZnO fabrication methods and its electrical, optical, and magnetic properties were presented.
