InxGa1−xAs (x=0.25–0.35) grown at low temperature

In_xGa_1−xAs (x=0.25–0.35) grown at low temperature on GaAs by molecular beam epitaxy is characterized by Hall effect, transmission electron microscopy, and ultrafast optical testing. As with low temperature (LT) GaAs, the resistivity is generally higher after a brief anneal at 600°C. High-resolution transmission electron microscopy shows all the as-grown epilayers to be heavily dislocated due to the large lattice mismatch (2–3%). When the layers are annealed, in addition to the dislocations, precipitates are also generally observed. As with LT-GaAs, the lifetime shortens as growth temperature is reduced through the range 300–120°C; also, the lifetime in LT-In_xGa_1−xAs is generally shorter in as-grown samples relative to annealed samples. Metal-semiconductor-metal photodetectors fabricated on the material exhibit response times of 1–2 picoseconds, comparable to results reported on GaAs grown at low temperature, and the fastest ever reported in the wavelength range of 1.0–1.3 μm.     

CMX469A和MSM7512B的无线Modem设计对比

分别基于CMX469A和MSM7512B设计实现无线数字Modem系统;说明系统关键部分的硬件实现方法和软件设计,并对两种设计方案进行对比分析。所设计的无线数字Modem具有设计简单、易于实现、功能完善的优点,可广泛应用于安防监控、数据采集等无线数传领域。     

推土机金属结构件故障频数模型

给出了揭示推土机金属结构件故障潜在原因的故障数据统计处理方法；建立了能预报规定期内金属结构件故障频数回归模型；并对金属结构件典型故障进行了分析．结果表明，金属结构件故障频数不仅决定于金属结构件材料的抗疲劳强度和抗拉强度，金属结构件的抗弯刚度、铰接件耐磨性能及随机载荷．而且同推土机工作环境气温密切相关．在冬季，低气温条件下，金属结构件故障具有多发性．金属结构件故障模式主要是推杆弯曲、推杆连接斜撑部位产生裂纹以及连接推杆和机架用的球铰接损坏等．推土机工作装置的薄弱环节是连接推杆和推土机用的销和销孔．     

基于新型半圆形电极金属-半导体-金属紫外光探测器的光电耦合优化

本文使用数值仿真器ISE-TCAD建立了新型半圆形电极金属-半导体-金属紫外探测器器件模型并研究了该探测器的器件特性。通过对新型半圆形电极结构探测器,传统结构探测器以及实验数据的全面对比验证了模型的正确性。其结果表明了该探测器的性能提升并说明了建立的物理模型对预测这种新型结构探测器性能增强而言是合适的。此外,通过调节该器件的结构参数实现优化目的,优化结果表明半圆形电极半径为2 μm, 电极间距为3 μm的探测器在290 nm具有峰值响应度0.177 A/W ,相应的外量子效率超过75%, 同时在0.3 V 偏压条件下归一化光暗电流对比度达到1.192E11 1/W。这些特性表明半圆电极金属-半导体-金属紫外光电探测器具有优异的光电集成应用前景。     

基于GPS和GPSOne的车载定位技术研究与实现

随着社会经济的发展,需要移动定位功能的场合越来越多.利用移动定位技术对车辆的运行进行定位和监控,可以更加有效、及时对车辆实施管理.文中研究了现有的多种定位技术,着重分析研究了GPS和GPS0ne定位技术,根据这两种定位技术的优缺点及系统运行成本的需要,提出了利用GPS和GPSOnc进行混合定位的新方法.     

势垒层对黑硅光电探测器性能影响的研究

讨论势垒层Si3N4的引入对黑硅光电探测器光电性能的影响。探测器采用金属一半导体一金属（MSM）器件结构在黑硅层和电极间增加一层势垒层以提高肖特基势垒,从而减低器件的暗电流。实验表明,在相同的光照情况下,有势垒层的探测器暗电流比无势垒层的探测器暗电流至少低1个数量级,且势垒层厚度增加30nm其暗电流降低约1个数量级,而...     

Ultraviolet-visible metal-semiconductor-metal photodetectors fabricated from InxGa1−xN (0≤x≤0.13)

Metal-semiconductor-metal (MSM) photodetectors have been fabricated on In_xGa_1−xN epitaxial films grown by metalorganic chemical vapor deposition within the composition range 0≤x≤0.13. The dark current and spectral response were measured for devices with a varying In mole fraction x. The devices, which had nominal finger widths and finger spacing of 5 μm, were biased with modest voltages in the range 2≤V_bias≤5 V. In general, turn-on wave-length and dark current increased with increasing x. Turn-on wavelengths ranged from λ=370 nm to 430 nm and dark current densities ranged from I_dark=2×10⁻² A/cm² (V_bias=5 V, x≈0.05) to 9×10⁴ A/cm² (V_bias=2 V, x≈0.13) depending on the In content, x, of the device active area.     

OEIC光接收机研究的湿法选择腐蚀

试验了用柠檬酸与双氧水系列腐蚀液来实现ＩｎＡｌ（Ｇａ）Ａｓ∶ＩｎＰ和ＩｎＧａＡｓ∶ＩｎＡｌＡｓ的选择腐蚀,达到了较好的效果,且工艺重复性好。同一单片上ＭＳＭ（金属－半导体－金属）光探测器的光响应度可达到０．５Ａ／Ｗ,ＨＥＭＴ器件最大跨导为３０５ｍＳ／ｍｍ,最大饱和电流密度为３５０ｍＡ／ｍｍ。完成了实现ＯＥＩＣ光接收机的关键一步。     

Study of grain boundaries influence on electrical properties of nitrides

The electronic conduction mechanism through grain boundaries in heteroepitaxial gallium nitride layers was explained by applying the model, which included three effects: thermionic emission over potential barrier, thermionic field emission through potential barrier and thermionic field emission through scattering barrier. Space charge potential barriers height at the grain boundary layer was estimated to be 80 meV from the measurement of the temperature dependence of layer resistivity. Influence of the deep traps location in the different regions of active layers of the MSM detector on the device performance was evaluated by 2D numerical simulation.     

MSM结构硅光探测器

采用 MSM 双肖特基势垒结构制作的硅光电二极管,在0.2～1.10μm波长范围内具有高的响应度。这种结构还可以构成横向光晶体管,共发射极电流增益为2～4倍。实验表明,MSM 结构是改善硅光电探测器光谱响应的良好结构。