Investigation on p-type doping of PBn unipolar barrier InAsSb photodetectors

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.

Degradation analysis and doping modification optimization for high-voltage P-type layered cathode in sodium-ion batteries

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.

Identification of P-type plasma membrane H^(+)-ATPases in common wheat and characterization of TaHA7 associated with seed dormancy and germination

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.

Realizing Cd and Ag codoping in p-type Mg_(3)Sb_(2)toward high thermoelectric performance

Mg_(3)Sb_(2)has attracted intensive attention as a typical Zintl-type thermoelectric material.Despite the exceptional thermoelectric performance in n-type Mg_(3)Sb_(2),the dimensionless figure of merit(zT)of p-type Mg_(3)Sb_(2)remains lower than 1,which is mainly attributed to its inferior electrical properties.Herein,we synergistically optimize the thermoelectric properties of p-type Mg_(3)Sb_(2)materials via codoping of Cd and Ag,which were synthesized by high-energy ball milling combined with hot pressing.It is found that Cd doping not only increases the carrier mobility of p-type Mg_(3)Sb_(2),but also diminishes its thermal conductivity(κ_(tot)),with Mg_(2.85)Cd_(0.5)Sb_(2)achieving a lowκtot value of∼0.67 W m^(−1)K^(−1)at room temperature.Further Ag doping elevates the carrier concentration,so that the power factor is optimized over the entire temperature range.Eventually,a peak zT of∼0.75 at 773 K and an excellent average zT of∼0.41 over 300−773 K are obtained in Mg_(2.82)Ag_(0.03)Cd_(0.5)Sb_(2),which are∼240%and∼490%higher than those of pristine Mg_(3.4)Sb_(2),respectively.This study provides an effective pathway to synergistically improve the thermoelectric performance of p-type Mg_(3)Sb_(2)by codoping Cd and Ag,which is beneficial to the future applications of Mg_(3)Sb_(2)-based thermoelectric materials.

Ga intercalation in van der Waals layers for advancing p-type Bi_(2)Te_(3)-based thermoelectrics

Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation of guest species in van der Waals(vdW)gap implemented for tunning properties has attracted much attention in recent years.We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi_(0.3)Sb_(1.7)Te_(3)(BST)for further improving thermoelectrics.The vdW-related defects(including extrinsic interstitial and intrinsic defects)induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture,thereby yielding excellent electrical properties,which are reflected in the power factor PF~4.43 mW·m^(-1)·K^(-2).Furthermore,the intercalation of Ga produces multi-scale lattice imperfections such as point defects,Te precipitations,and nanopores,realizing the low lattice thermal conductivity in BST-Ga samples.Ultimately,a peak zT~1.1 at 373 K is achieved in the BST-1%Ga sample and greatly improved by~22%compared to the pristine BST.The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.

棉花P-type ATPases基因的克隆及表达分析

为了探明棉花P-type ATPases基因在植物不同组织和多种逆境条件下的表达情况,利用棉花黄萎病菌的P-type ATPases蛋白序列,在GenBank中搜索棉花EST序列,得到2个同源的棉花EST片段,结合RACE和Genome walking获得了这个基因的完整读码框序列,其开放阅读框长度为3 570 bp,编码1 190个氨基酸,与毛果杨、蓖麻的同源性达86%左右,将其命名为Gbpatp。洋葱表皮亚细胞定位观察结果显示,Gbpatp编码的蛋白分布在细胞膜上。RT-PCR技术检测组织表达特异性分析表明,P-type ATPases在茎和棉絮中的表达量较高,在种子中低水平表达,在叶片和花蕾中表达量极低,说明Gbpatp可能与棉花较成熟的器官茎、棉絮和种子的生长发育密切相关。在逆境胁迫中发现,干旱处理后Gbpatp的表达强烈,并且随处理时间延长表达量逐渐增加;重金属Cu2+处理24 h后Gbpatp表达量升高,但48 h急剧下降;Gbpatp在低温处理下也有轻微表达。激素诱导后发现,Gbpatp对赤霉素和脱落酸均有响应,随胁迫时间延长其表达量仍能维持在一定水平。

微紫青霉菌(Penicillium janthinellum)P-type ATPase及金属硫蛋白相关基因的克隆

本研究以高抗多种重金属盐的微紫青霉菌(Penicillium janthinellum)菌株GXCR为材料构建基因组fosmid文库。其插入片段集中在36～50kb,含13348个克隆,重组率为100%,大约覆盖了GXCR基因组的14.83倍。基于序列特异性和简并引物,利用PCR扩增分析了与酿酒酵母(Saccharomyces cerevisiae)重金属盐抗性相关的CRS5和CUP2基因;基于兼并引物和序列特异性引物,利用PCR扩增分析了GXCR的P-type ATPase基因。通过菌落原位杂交和Southern blot鉴定了一个含铜转运P-type ATPase基因的阳性fosmid克隆,经亚克隆测序分析表明该基因与棒曲霉(Aspergillus clavatus菌株)NRRL1的P-type copper ATPase相似性达97%。没有筛选到与CRS5和CUP2基因同源的克隆,说明GXCR中可能不存在与酿酒酵母CUP2和CRS5高度同源的MT基因,同时也暗示酵母与丝状真菌的重金属盐的抗性机制有本质上的差异或者独特性。

Temperature-Dependent Raman Scattering of Phonon Modes and Defect Modes in GaN and p-Type GaN Films

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.

A Novel Sr_2CuInO_3S p-type semiconductor photocatalyst for hydrogen production under visible light irradiation

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.

A study of transition from n-to p-type based on hexagonal WO3 nanorods sensor

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.

Enhanced thermoelectric performance in p-type Mg3Sb2 via lithium doping

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.

Efficiency enhancement of ultraviolet light-emitting diodes with segmentally graded p-type AlGaN layer

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.

Identification of anomalous fast bulk events in a p-type point-contact germanium detector

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.

Growth of nitrogen-doped p-type ZnO thin films prepared by atomic layer epitaxy

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.

Recent progress of the native defects and p-type doping of zinc oxide

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.

Electrical Properties of Li-doped P-type ZnO Ceramics

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.

Development in p-type Doping of ZnO

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.

The effect of electronic orbital interactions on p-type doping tendency in ZnO series： First-principles calculations

The electronic structures and optical properties of B3 ZnO series of Zn4X4-yMy（X ：O, S, Se or Te; M = N, Sb, C1 or I; y = 0 or 1） are studied by first-principles calculations using a pseudopotential plane-wave method. The results show that Zn d-X p orbital interactions play an important role in the p-type doping tendency in zinc-based Ⅱ-Ⅵ semiconductors. In ZnX, with increasing atomic number of X, Zn d-X p orbital interactions decrease and Zn s-X p orbital interactions increase. Additionally, substituting group-V elements for X will reduce the Zn d-X p orbital interactions while substituting group-VII elements for X will increase the Zn d-X p orbital interactions. The results also show that group-V-doped ZnX and group-Ⅷ-doped ZnX exhibit different optical behaviours due to their different orbital interaction effects.

Preparation and Photovoltaic Properties of p-Type Nano-ZnFe_2O_4

p-Type nano-ZnFe2O4 semiconductors were gained by high-prssure treatment.Surface photovoltaic spectrum（SPS） and transient photovoltaic technology（TPV） were used for studying the photogenerated charge of nano-ZnFe2O4.Results show that the photovoltaic behavior of nano-ZnFe2O4 changed as the processing pressure increased.When the processing pressure was higher than 2 GPa,both SPS response interval and peak changed significantly.XPS results show that the non-lattice oxygen entered into the lattice and the content of lattice oxygen increased with the increase of processing pressure.The material changed from oxygen vacancy type to oxygen excess type and the photoelectric properties changed from n-type to p-type when the processing pressure is higher than 2 GPa.

The low temperature growth of stable p-type ZnO films in HiPIMS

In this study,the influence of substrate temperature on properties of Al-N co-doped p-type ZnO films is explored.Benefitting from the high ionization rate in high-power impulsed magnetron sputtering,the concentration of ionized nitrogen N+and ionized zinc Zn+were increased,which promoted the formation of ZnO films and lowered the necessary substrate temperature.After optimization,a co-doped p-type ZnO thin film with a resistivity lower than 0.35Ωcm and a hole concentration higher than 5.34×10^(18)cm^(-3)is grown at 280°C.X-ray diffraction results confirm that Al-N co-doping does not destruct the ZnO wurtzite structure.X-ray photoelectron spectroscopy demonstrates that the presence of Al promotes the formation of acceptor(No)defects in ZnO films,and ensures the role of Al in stabilizing p-type ZnO.