激光辐照对长滤HgCdTe光导探测器电学参数的影响

对长波HgCdTe光导探测器进行了低于其永久损伤阈值的变功率激光辐照，测量辐照前后器件的电阻－温度特征，用电阻－温度特征研究材料参数的方法对实验结果进行拟合，结果表明辐照后HgCdTe探测器件的组分变大，并由此计算得到探测器性能突变后，器件的电子迁移率与电子浓度均有一定程度减小。认为这可能是由于激光辐照的热效应使N型HgCdTe光导器件的表面及体内均产生的一定的变化所致。     

PECVD法制备SiO_xN_y膜Ⅰ—Ⅴ特性和击穿机理的测试分析

对等离子体增强化学汽相起积（PECVD）法制成SiOxNy薄膜组成的MIS结构样品，由集成测试系统测量Ⅰ－Ⅴ特性，用晶体管特性图示仪测试击穿行为。分析研究了该薄膜的Ⅰ－Ⅴ特性和击穿机理，探讨了膜的击穿电场及其随混合气体比例、反应空气压、衬底工作温度的变化关系。     

静压下Znse／Zn_（1－x）Cd_xSe应变超晶格的光致发光研究

本文首次在室温和０—２．５ＧＰａ静压范围内研究了Ｚｎｓｅ／Ｚｎ０．２６Ｃｄ０．２６Ｓｅ应变超晶格的静压光致发光，观察到了室温条件下的超晶格阱层的重空穴激子跃迁随压力的亚线性变化的特性．经过计算机拟合实验数据得到了一阶和二阶压力系数．理论计算得到的一阶压力系数与实验得到的压力系数符合得较好。     

X射线衍射的发现

简单介绍了埃瓦尔德（Ewald P P）、劳厄（von Laue M）和布拉格父子（Bragg　W　H及Bragg　W　L）在1912年发现X射线衍射方面的贡献.1911年埃瓦尔德在索末菲的指导下在慕尼黑大学从事博士论文研究,劳厄在与他的讨论中了解到晶格的平移周期与X射线的波长属于同一量级,因此想到在二维光栅的两个衍射方程组中再加一个类似的方程,就可以描述X射线在三维晶体中的衍射.在此假设的指导下,Friedrich　W和Knipping P在1912年4月开始用CuSO4后来用闪锌矿（立方ZnS）进行实验,很快就得到X射线衍射的证据.这不但证明了X射线的波动性,还确定了晶体的三维周期性.老布拉格在1912年夏得知这个消息,与他儿子小布拉格一道尝试用X射线的粒子性解释它,并由小布拉格在剑桥大学重复这个实验.根据衍射斑点的椭圆形状和从Pope与Barlow那里学到的晶格理论（由此得知ZnS具有面心立方晶格）,小布拉格将X射线在晶体中的衍射看作是X射线从一些晶格平面的反射,从而推导出著名的布拉格方程.布拉格父子开拓了X射线晶体结构分析这门新兴学科,从简单的无机化合物和矿物,逐渐发展到有机化合物和生物大分子.劳厄和布拉格父子分别强调慕尼黑和剑桥的优良科学环境对发现X射线衍射的重要性.鉴于埃瓦尔德在发现X射线衍射的作用及他后来在倒易格子及动力学衍射理论方面的贡献,不少晶体学家认为他也应获得诺贝尔物理奖.     

Thermal annealing effects on p-type conductivity of nitrogendoped ZnSe grown by metalorganic vapor phase epitaxy

Post-growth thermal annealing (e.g., 500°C, 30 min), is proposed as one of the promising techniques to realize and to improve the quality of p-type ZnSe layers grown by metalorganic vapor phase epitaxy (MOVPE). The layers were grown at low temperature (350°C) by photo-assisted MOVPE with doping nitrogen from tertiarybutylamine (t-BuNH₂). The flow rate of t-BuNH₂ was limited to be relatively low, in order to avoid heavy doping, with which as-grown layers exhibited electrically high-resistivity; but the thermal annealing converted the layers to p-type. As the as-grown layers exhibited the stronger donor-to-acceptor pair recombination lines or the weaker donor-bound excitonic emission (I_x) lines in photoluminescence, the annealed layers resulted in higher net acceptor concentration, which was 1 x 10¹⁷ cm⁻⁴ at the optimum conditions at present.     

Erratum

Epitaxial layers of ZnSe ranging in thickness from 5μm to 30 μm have been grown on GaAs (100) substrates over the temperature range 240° C to 340° C by atmospheric pressure MOVPE employing dimethylzinc and hydrogen selenide. An optimum growth temperature of 280 ± 5° C has been identified and when grown at this temperature the ZnSe epitaxial layers exhibit low resistivity (ρ _{298 K} ≤ 10 ohm · cm), a low compensation ratio (θ _{298 K} = 0.27), a carrier mobility (μ _{298 K} ) of 250 ±10 cm ² V ^-1 s ^-1 ) and are n -type ( n _{298 K} = 8.0 × 10 ¹⁴ cm ^-3 ). The ratio of photoluminescence intensity measured at 298K and at 12 K is high (10 ⁴ ) and is dominated by a sharp emission due to excitons bound to neutral donors at 2.7956 eV. Mass spectrometric investigations of the chemical reactions occurring inside the reactor in the presence of the GaAs substrate indicate significant surface-controlled reactivity in the region of 280° C. The online version of the original article can be found at     

Cd and Te-based ohmic contact materials to p-Type ZnSe

In order to explore a possibility of forming an intermediate semiconductor layer with low Schottky barrier by the conventional deposition and annealing technique, the electrical properties of Cd and Te-based contacts on the nitrogendoped ZnSe substrates have been investigated. Cd in the Cd/W contact reacted with the ZnSe substrate after annealing at temperatures above 250°C and formed epitaxial Cc_x}Zn_1−xSe layers, leading to reduction of the “turn-on” voltage (V_T) from about 11 to 6 V (here, a slash “/” between Cd and W means the deposition sequence). The reduction of the V_n} value by annealing at elevated temperatures was also observed for the Bi-Cd/W and In-Cd/W contacts. The average Cd composition (x) in the Cd_n}Zn_1−xSe layers was measured to be larger than 0.9, which agreed with the values estimated from the calculated Cd-Zn-Se phase diagrams. The ohmic behavior was strongly influenced by the thickness of the Cd_xZn_1−xSe layer, the density of misfit dislocations formed at the interface between the Cd_x Zn_1−x Se and the ZnSe, and/or the total area of the Cd Zn. Se layers covering the ZnSe surface. The present result suggests that formation of the large-areal Cc_xZn_1−xSe layers with thin thickness is crucial to achieve further reduction of the V_T value by the conventional deposition and annealing technique. Also, the V_T reduction was not obtained for the Te/W contact even after annealing at temperatures close to 300°C, which was explained to be due to absence of ternary ZnSe_1−xTe_n intermediate layers.     

On the Determination of Charge Profiles in Epitaxial Layers of ZnSe by Capacitance Measurements

The doping profile in semiconducting epitaxial layers is often deduced from the behavior of the capacitance of a Schottky contact evaporated onto the surface of the layer as a function of the bias voltage. It is shown on the example of Au/ZnSe/GaAs heterostructures that the heterojunction with the substrate in series with this Schottky contact leads to erroneous profiles, if no special care is taken in the choice of the frequency used in measuring the capacitance. This frequency must be chosen below the cutoff frequency which is apparent in the graphs of the capacitance vs the frequency.     

非线性干涉滤光片N形反射光双稳器件的研究

对Ｎ形反射光双稳器件的结构进行了理论设计和实验研究，对光双稳的重要参数δＩ０、δＩｒ与初始失调量δ之间的关系进行了描绘，并通过引入ＺｎＳｅ薄膜的色散关系，使这一理论方法具有自洽性。最后，文章给出了通过这一方法设计的非线性干涉滤光片Ｎ形反射光双稳器件的实验结果。     

Carrier Dynamics Study of CdxZn1-xSe/ZnSe (x = 0.2) Multiple Quantum Wells

In this paper, nonlinear optical properties of Cd_xZn_1-xSe/ZnSe (x = 0.2) multiple quantum wells were studied by low temperature steady-state and transient photoluminescence at high excitation densities. The biexciton transition was observed on the low energy side of the exciton transition. Based on the characteristics of stimulated emission observed in similar structures, we suggest the biexciton transition as the mechanism for stimulated emission. Optical degradation was also studied by room temperature photoluminescence using femtosecond laser pulses as the excitation source. The results confirm the formation of nonradiative recombination centers with a saturating degradation effect after about 10 min of exposure.