基于扩散模型的ZnO/p-Si异质结伏安特性研究

Investigation into Voltage-Current Characteristics of ZnO/p-Si Heterojunction Based on Diffusing Models

为了揭示ZnO/p-Si异质结的导电机理,基于p-n结扩散模型和Anderson扩散模型推导了ZnO/p-Si异质结在理想情况下的伏安特性,并分析了掺杂浓度、工作温度以及能带补偿的影响.结果表明:当正向偏压超过势垒高度时,界面两边多数载流子由耗尽变为堆积,形成反向势垒,对异质结的正向电流起阻碍作用;当外加正向电压等于内建势垒高度时,伏安特性曲线出现转折点;当外加正向电压超过转折点电压时,电流密度随电压升高而增大的速度减缓;反向饱和电流密度随p-Si受主掺杂浓度的增加和工作温度的降低而减小,但与ZnO的掺杂浓度和导带补偿无关;p-Si和ZnO的掺杂浓度减小、工作温度升高以及导带补偿增大均会引起转折点位置对应的外加正向电压减小.

In order to reveal the conduction mechanism of ZnO/p-Si heterojunction,the voltage-current characteristics of the heterojunction in ideal conditions are investigated based on the p-n junction diffusing model and the Anderson diffusing model,and the effects of doping concentration,working temperature and band compensation on the voltage-current characteristics are analyzed.The results indicate that（1） when the forward bias exceeds the built-in potential,the state of most carriers at the two sides of the interface changes from exhaustion into accumulation,thus forming reverse barrier to obstruct the movement of positive electric current in ZnO/p-Si heterojunction;（2） when the applied voltage equals the built-in potential,an inflection point occurs in the voltage-current curve;（3） when the applied voltage exceeds the inflection point voltage,the increasing speed of the current density with the voltage becomes slow;（4） the reverse saturation current density decreases with the increase in doping concentration of p-Si and with the decrease in working temperature,but it is insensitive both to the doping concentration of ZnO and to the conduction band offset;and（5） the applied voltage corresponding to the inflection point is positively related to the doping concentrations of p-Si and ZnO but negatively related to the working temperature and the conduction band offset.