金属/Hg1-xMnxTe接触的I-V特性研究

分别采用溅射和蒸发镀膜法在Hg1-xMnxTe试样表面形成了Au/Hg1-xMnxTe和Al/Hg1-xMnxTe接触,并用Aligent4155c I-V测试仪对其I-V特性进行了测量,随后对试样在10%NH4F:10%H2O2:H2O中进行了钝化处理,并对处理后的试样再次进行了I-V测量,对于测试结果用热电子发射-扩散理论进行了分析.结果表明:Au与Hg1-xMnxTe形成了良好的欧姆接触,而Al与Hg1-xMnxTe形成了具有整流特性的肖特基接触,其肖特基势垒的理论推算值为0.38eV.钝化处理后的试样,其表面漏电现象明显降低,Au/Hg1-xMnxTe接触的电流下降幅度在0.1V时最大,为76.1%;而Al/Hg1-xMnxTe接触在0.2V时最大,为93.2%.随着偏压的进一步增大,两种接触的电流减小的幅度都逐渐变小.     

新型红外探测器材料Hg1-x-y CdxZnyTe研究

采用移动加热器法(THM)进行了新型红外探测器材料 Hg1-x-yCdxZnyTe(MCZT)的晶体生长,获得的MCZT晶片经汞源退火后进行了光学特性、结构特性、电学性能和组分均匀性的检测与分析,并且初步制作成近室温工作的长波光电导器件,对器件性能进行了测试与分析。结果表明用移动加热器法生长Hg1-x-yCdxZnyTe晶体是成功的,获得晶片的材料特性与器件性能初步达到了应用水平。     

MCZ硅单晶反型杂质含量研究

利用范德堡－霍尔测量方法对ＭＣＺ硅单晶的反型杂质含量进行了对比测量，所得结果表明，ＭＣＺ硅单晶的反型杂质含量低于ＣＺ硅单晶约半个数量级之多，文中还提出了一种适合于大指范德堡－霍尔测量的接触电极制备方法－选择扩散法，并给出了确保测量方法带来影响的扩散结深与样品厚度比值上限ｘｊ／ｄ＝０．０１。测量过程中应用了有限尺寸接触电极修正理论。     

溅射功率对磁控溅射ZnO∶Al(ZAO)薄膜性能的影响

采用射频磁控溅射工艺,以高密度氧化锌铝陶瓷靶为靶材,衬底温度控制在室温,在玻璃基底上制备了透明导电Zn O∶Al(ZAO)薄膜。利用X射线衍射仪(XRD)、原子力显微镜(AFM)、紫外-可见光谱仪和范德堡法,系统研究了不同溅射功率对薄膜的结构、形貌及光电特性的影响。结果表明,不同溅射功率对薄膜的光透射率影响不大,而对薄膜结晶和电学性能影响较大。XRD表明薄膜为良好的c轴择优取向;可见光区(400~600 nm)平均透过率达到85%以上;在120W下沉积的薄膜电学性能达到了最佳。     

退火温度对Bi_2Te_(2.7)Se_(0.3)薄膜的微结构及热电性能的影响

采用瞬间蒸发技术在温度为473 K的玻璃基体上沉积了厚度为800 nm的N型Bi2Te2.7Se0.3热电薄膜,并在373 K～573 K进行1小时的真空退火处理。利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)和能量散射谱(EDS)分别对薄膜的物相结构、表面形貌以及化学计量比进行表征。采用表面粗糙度测量仪测定薄膜厚度,薄膜的电阻率采用四探针法在室温下进行测量,在室温下对薄膜的Seebeck系数进行表征。霍尔系数,电子浓度和迁移率在300 K用Van der Pauw方法进行测量。退火温度为473 K时,电阻率和Seebeck系数分别为2.7 mΩ.cm和?180μV/K,热电功率因子最大值为12μW/cmK2。     

硒化镉(CdSe)单晶体的变温霍尔效应研究

通过变温（20～300K）霍尔效应测量,研究了CdSe单晶体的电阻率ρ（T）、载流子浓度n（T）、霍尔系数RH（T）和霍尔迁移率μH（T）的温度依赖关系.实验结果表明CdSe单晶体的导电类型总为n型,且它的电阻率与载流子浓度的温度依赖关系与n-Si单晶类似.通过拟合禁带宽度约为1.7eV.本文还进一步研究了本征区、饱和区、弱电离区内电子浓度的变化和霍尔因子γ随温度变化关系,并由此计算出杂质电离能（24.7meV）与补偿度（23.7%）.上述结果表明CdSe单晶体具有优良的电学特性,是制作室温核辐射探测器的理想材料.     

基于范德堡法的溶液电导率绝对测量方法

将范德堡电阻率测量方法用于溶液电导率的测量中,设计了封闭式四电极电导池;测量系统采用交流微电流源提供激励信号,对响应信号进行放大与处理,通过微机系统实现与上位机的通信与控制。研究了范德堡法电导率测量的影响因素,通过对标准溶液的测量,验证了该方法测量范围可达0~40 mS/cm、测量误差控制在±1%,可以作为电导率基准测量方法。     

压力对CoSb_(2.750)Te_xGe_(0.250-x) n型方钴矿化合物的电输运性能的影响

采用高温高压方法,在900K的温度条件下,成功合成出CoSb2.750 TexGe0.250-x(x=0.125,0.175,0.200)n型方钴矿化合物,并考察了不同的压力对其电输运性能的影响规律。室温下对样品的电阻率(ρ),Seebeck系数(S)进行了测试分析。电学性能测试表明,方钴矿CoSb2.750 TexGe0.250-x化合物的导电类型为n型,电阻率和Seebeck系数的绝对值随着压力的升高而增加,随着Te掺杂量的增加而降低。功率因子随合成压力增大而降低,随Te掺杂量的增加而升高。CoSb2.750Te0.200Ge0.050在2GPa时具有最大的功率因子为7.59μW/(cm.K2)。     

氧压对用PLD法生长氧化锌薄膜的电学特性的影响

本文研究了用脉冲激光沉积（PLD）法制备ZnO薄膜，给出了在不同氧压下生长氧化锌（ZnO）薄膜的XRD谱、表面的AFM图以及电阻率、迁移率、载流子浓度以及导电类型等电学特性，为探索制备P型ZnO薄膜提供实验依据。     

半导体电学特性四探针测试技术的研究现状

四探针法是材料学及半导体行业电学表征较常用的方法,其原理简单,能消除接触电阻影响,具有较高的测试精度.由厚块原理和薄层原理推导出计算公式,并经厚度、边缘效应和测试温度的修正即可得到精确测量值.据测试结构不同,四探针法可分为直线形、方形、范德堡和改进四探针法,其中直线四探针法最为常用,方形四探针多用于微区电阻测量.本文综述了四探针测试技术的基本理论,包括四探针法的分类、原理和修正,并阐述了四探针测试技术在微观领域的发展.     

Role of confinement on carrier transport in Ge-Si(x)Ge(1-x) core-shell nanowires

We examine the impact of shell content and the associated hole confinement on carrier transport in Ge-Si(x)Ge(1-x) core-shell nanowires (NWs). Using NWs with different Si(x)Ge(1-x) shell compositions (x = 0.5 and 0.7), we fabricate NW field-effect transistors (FETs) with highly doped source/drain and examine their characteristics dependence on shell content. The results demonstrate a 2-fold higher mobility at room temperature, and a 3-fold higher mobility at 77K in the NW FETs with higher (x = 0.7) Si shell content by comparison to those with lower (x = 0.5) Si shell content. Moreover, the carrier mobility shows a stronger temperature dependence in Ge-Si(x)Ge(1-x) core-shell NWs with high Si content, indicating a reduced charge impurity scattering. The results establish that carrier confinement plays a key role in realizing high mobility core-shell NW FETs.     

Preparation and properties of epitaxial films of indium-doped lead tin telluride

Several hundred epitaxial films of indium-doped lead tin telluride were grown on BaF₂ substrates using a hot-wall method and a source material containing 0.5 at.%In. Films were grown from source materials containing SnTe at concentrations of 0, 22, 24.8 and 27.7 mol.%. The growth procedure, source material preparation and substrate preparation are described. The films were characterized by van der Pauw measurements of the mobility and carrier concentration at room temperature and 77 K. As finally developed, the growth procedures gave a high yield of films with mobilities at 77 K in the range of 3.5–4.5 m² V^-1s^-1.     

Hydrothermal derived nanostructure rare earth (Er,Yb)-doped ZnO: structural,optical and electrical properties

The structural, optical and electrical properties of undoped and rare-earth (Er, Yb) doped zinc oxide (ZnO) nanopowder samples synthesized by hydrothermal method were investigated. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy. The optical properties of undoped and rare-earth (Er, Yb) doped ZnO were carried out with UV–visible diffuse reflectance spectroscopy techniques. XRD results reveal that Yb and Er doped ZnO nanopowders have single phase hexagonal (Wurtzite) structure without any impurities. SEM analysis indicate that dopants with different radii affected the surface morphology of ZnO nanostructures. The optical band gap of all samples were calculated from UV–Vis diffuse reflectance spectroscopy data. We have obtained band gap values of undoped, Er and Yb doped ZnO as 3.24, 3.23, 3.22 eV, respectively. Electrical characterization of the samples were made in the 280–350 K temperature range using Van der Pauw method based on Hall effect measurement. The carrier concentrations decreased for both Er and Yb doping while the Hall mobility and electrical resistivity increased with Yb, Er doping compared to undoped ZnO nanopowder at room temperature. The temperature dependent resistivity measurements of Er doped ZnO showed a metal–semiconductor transition at about 295 K, while Yb doped ZnO showed characteristic semiconductor behavior.     

高迁移率AlGaN-GaN二维电子气

用金属有机物气相外延方法在（０００１）蓝宝石衬底上生长了ＡｌｘＧａ１－ｘＮ／ＧａＮ二维电子气结构。Ａｌ０．１３Ｇａ０．８７Ｎ（７００ｎｍ）／ＧａＮ（６００ｎｍ）异质结的室温电子迁移率达１０２４ｃｍ＾２／Ｖｓ,而ＧａＮ体材料的室温电子迁移率为３９０ｃｍ＾２／Ｖｓ;该异质结的７７Ｋ电子迁移率达３５００ｃｍ＾２／Ｖｓ,而ＧａＮ体材料的电子迁移率在１８５Ｋ下达到峰值,为４９０ｃｍ＾２／Ｖｓ,７７Ｋ下下降到     

Structural,optical and electrical properties of spray pyrolytically deposited thin films of CuInS2

CuInS₂ is a promising chalcopyrite semiconducting material for solar cell fabrication. Using aqueous solutions of cupric chloride, indium trichloride and thiourea, we deposited thin CuInS₂ films on glass at 350°C and studied their structural, optical and electrical properties. From the XRD pattern the chalcopyrite structure of these films was confirmed. The films were polycrystalline. The grain size estimated from scanning electron micrographs was found to be of the order of 1μm. Resistivity of the film was measured for temperatures ranging from 77 to 473 K. Band gap values were determined from optical transmission data. Hall mobility and carrier concentration at room temperature were calculated using Van der Pauw-Hall method.     

二元Al-Li合金的低温力学性能

本文研究了纯 Al,Al-ILi 和 Al-2.5Li 合金力学性能与实验温度的关系。结果表明,这些合金在低温下有很显著的增强增韧现象,但屈服强度变化较小,加工硬化能力显著提高;时效温度与 Al-2.5Li 合金低温力学性能改善无关,低温断裂前比室温时需经历更大的形变。     

Enhancement of microelectronic device performances by photothermal annealing under SiCl4 ambient

The use of low cost silicon wafers seems to be very attractive for photovoltaic and microelectronic devices. However, this material is widely contaminated by different impurities particularly transitions metals, which deteriorate the lifetimes and the bulk diffusion lengths of the minority charge carriers. One possible way to overcome this undesirable behavior is to include an efficient purification technique in the process of device fabrication. In this work, we present the effect of photothermal treatments of monocrystalline Czochralski silicon substrates under SiCl₄/N₂ atmosphere using a thin sacrificial porous silicon layer. The main results show a decrease of the resistivity over 40 μm depth. The Hall mobility of the majority charge carriers is improved from 300 to 1417 cm² V^− 1 s^− 1. The capacitance–voltage (C–V) characteristics of metal/SiO₂/Si (MIS) structures indicate a decrease of carrier concentration which confirms the results obtained by Hall Effect and Van Der Pauw method. The reduction of boron concentration in Czochralski silicon may reduce boron- and oxygen related metastable defect centers.     

Zn(1-x)MnxTe diluted magnetic semiconductor nanowires grown by molecular beam epitaxy

It is shown that the growth of II-VI diluted magnetic semiconductor nanowires is possible by the catalytically enhanced molecular beam epitaxy (MBE). Zn(1-x)MnxTe NWs with manganese content up to x=0.60 were produced by this method. X-ray diffraction, Raman spectroscopy, and temperature dependent photoluminescence measurements confirm the incorporation of Mn(2+) ions in the cation substitutional sites of the ZnTe matrix of the NWs.