白光LED的加速老化特性

对两组GaN基白光发光二极管（LED）进行了对比温度加速老化实验,环境温度分别是80,100℃。随着老化温度的升高,电流-电压（I-V）曲线的隧道电流段、扩散电流段以及反向漏电电流均增加,而串联电阻段则变化较小,这是位错密度升高和金属杂质沿着螺旋位错聚集及移动的结果;电容-电压（C-V）曲线中反向偏压下电容减少,正向偏压下电容增大,这是由于螺位错和混合位错产生了漏电的通道;电致发光光谱中黄光荧光成分比重增加;光通量随时间开始缓慢降低,在某一个时刻突然急剧降低,显示各个老化因素累积的影响会在某一时刻导致白光LED突然失效。最后使用阿列纽斯关系计算出所用白光LED的寿命为2．3万小时。     

电化学C-V法研究掺硅GaAs材料载流子浓度的分布

电化学C-V法是当前测量化合物半导体载流子浓度纵向分布的非常重要的方法.本文采用电化学C-V法研究了MOCVD生长的掺硅GaAs多层薄膜的载流子浓度的面分布和纵向分布,并对测试结果进行分析.研究表明电化学C-V法测得的载流子浓度数据可以为研究掺硅GaAs半导体材料载流子浓度工艺优化和改进提供重要指导依据.     

New electrolytes for n-type InP and electrochemical C-V profiling of a semiconductor optical amplifier device structure

New electrolyte systems for profiling n-type indium phosphide (InP) have been reported and are compared with the conventional HCl electrolyte. Among the new electrolytes, the electrolyte comprising HNO₃-HF-H₂O has better characteristics and is best suited for profiling InP material. Both epitaxial layers and substrate materials have been subjected to electrochemical carrier concentration profiling using the new electrolyte and the estimated concentration values are compared with that of Hall effect measurements. Barrier heights of the new electrolytes have been calculated. For the first time, the dopant profiling of a complete device structure grown by the chemical beam epitaxy technique for the realization of laser and semiconductor optical amplifier structures has been presented. Received: 1 February 1999 / Accepted: 1 April 1999     

Accurate capacitance-voltage characterization of organic thin films with current injection

To deal with the invalidation of commonly employed series model and parallel model in capacitance-voltage (C-V) characterization of organic thin films when current injection is significant, a three-element equivalent circuit model is proposed. On this basis, the expression of real capacitance in consideration of current injection is theoretically derived by small-signal analysis method. The validity of the proposed equivalent circuit and theoretical expression are verified by a simulating circuit consisting of a capacitor, a diode, and a resistor. Moreover, the accurate C-V characteristic of an organic thin film device is obtained via theoretical correction of the experimental measuring result, and the real capacitance is 35.7% higher than the directly measured capacitance at 5-V bias in the parallel mode. This work strongly demonstrates the necessity to consider current injection in C-V measurement and provides a strategy for accurate C-V characterization experimentally.