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本文讨论在GaAs n~+-n-n~+夹层结构的Cunn器件中畴的静止-渡越-静止模式,进行了实验观察和计算机模拟,指出在超过阈值的偏置电压下,当畴的耗尽层进入阳极附近的高掺杂区后,会逐渐停止下来形成准静态畴,这时畴外电场达到最大值.如果这时阴极凹口仍不能形成新畴,则准静态畴将进一步调整成为真正的静止畴,而畴外电场也将由最大值下降到一个与偏压无关的固定值.经过理论分析,得到了静止畴所固有的与外加偏压无关的畴外电场与有源区掺杂浓度的关系式,并和计算机模拟的结果相比较,得到很好的符合.如果偏压的增加使准静态畴所对应的畴外电场最大值已经足够使阴极凹口形成新的畴,则静止畴将转变为渡越畴.如果偏压继续增加,使积累层尾部覆盖了阴极凹口,则畴会再次静止下来,直到偏压增加到畴发生雪崩为止.计算和实验表明,后一个静止区的电压变化范围要比前一个大得多.本文还讨论了两个转变电压和温度的关系及扩散系数对静止畴的影响.
In this paper, we discuss the stationary-transition-static modes of Cunn devices with GaAsn ~ + -nn ~ + sandwich structure. The experimental observations and computer simulations are carried out. It is shown that when the threshold voltage is exceeded, After the layer enters the highly doped region near the anode, it gradually stops down to form a quasi-static domain, in which case the electric field outside the domain reaches a maximum value. If the cathode notch can not form a new domain at this time, the quasi-static domain will be further adjusted to be true , And the out-of-domain electric field will also decrease from a maximum value to a fixed value unrelated to bias.By theoretical analysis, the intrinsic electric field and active region doping concentration , Which is in good agreement with the results of computer simulation.If the bias voltage increases so that the maximum electric field outside the domain corresponding to the quasi-static domain is enough for the cathode to form a new domain, then the quiescent domains Will change to a transitional domain.If the bias voltage continues to increase so that the tail of the accumulation layer covers the cathode notch, the domains will stand still again until the bias voltage increases to the extent that an avalanche occurs.The computations and experiments show that in the latter stationary region Voltage changes The range is much larger than the previous one.This paper also discusses the relationship between the two transition voltages and temperature and the effect of diffusion coefficient on stationary domains.