真空中冲击电压下硅半导体的泄漏电流及沿面闪络特性

Characteristics of Leakage Current and Surface Flashover of Silicon under Impulse Voltage in Vacuum

在冲击电压下 ,通过在真空中对采用和未采用化学腐蚀表面处理的硅半导体的实验表明 ,试品的表面状况对其泄漏电流和沿面闪络特性有着很大的影响 ,在沿面闪络之前 ,未经处理试品的泄漏电流表现为欧姆性电流 ,而表面处理过的试品表现为空间电荷限制电流特性 ;同时两类试品表面的放电通道也表现出不同的特征。提出了一个新的模型来描述半导体材料沿面闪络的发展过程 ,即由焦耳热效应诱导的电流细丝现象而发展成最终的闪络 ,并认为这是一个发生在半导体表层内的过程 ,在靠近真空的侧面这一表层厚度约为 2 μm。

Two kinds of silicon samples with distinct surface treatment,i.e.,one is the chemically surface-etched and the other is the surface-unetched,were used to investigate the characteristics of leakage current and surface flashover of semiconductor under impulse voltage in vacuum.The experimental results showed that the surface conditions of samples affected these characteristics greatly.Before flashover,the Ohmic current was observed for unetched samples and the space charge limited (SCL) current for etched samples,respectively.Meanwhile both samples showed quite different flashover tracks.It is believed that all the phenomena are due to their different surface states.A new model has been proposed to describe the development process of surface flashover along semiconductor,i. e.,which is induced by the Joule heating effect and subsequent current filament.Moreover it is suggested that the flashover occurs in silicon surface layer near the clectrodes contacted and the vacuum ambient,and the surface layer is about 2μm thick.