InAlN/GaN/BGaN HEMT的高温直流特性研究

High temperature DC characteristics of InAlN/GaN/BGaN HEMT

对比分析了晶格匹配的InAlN/GaN与InAlN/GaN/BGaN高电子迁移率晶体管(HEMT)在不同温度(300~500 K)条件下的直流特性。结果表明,随着温度的升高,传统的InAlN/GaN HEMT器件表现出了严重的短沟道效应,具体表现在器件关断困难、栅控能力变差、阈值电压漂移以及亚阈值摆幅明显变大等。同时,由于电子限域性较差,传统的InAlN/GaN HEMT器件关态漏电现象严重。引入B摩尔分数为1.5%的BGaN缓冲层有利于InAlN/GaN HEMT器件在高温条件下仍保持较好的直流性能。当温度达到500 K时,InAlN/GaN/BGaN HEMT器件的阈值电压始终保持在-3.2 V左右,亚阈值摆幅为366 mV/dec,关态漏电流为3μA/mm,关断耗散功率为45μW/mm,均明显优于传统的InAlN/GaN HEMT器件。此外,相对于传统的InAlN/GaN HEMT而言,InAlN/GaN/BGaN HEMT器件的峰值跨导与饱和漏电流略低,但随着温度的升高,两器件的差距逐渐缩小。

The drain-current(DC)characteristics of lattice-matched InAlN/GaN and InAlN/GaN/BGaN high electron mobility transistor(HEMT)at different temperatures(300-500 K)were compared and analyzed.With the increase of temperature,the traditional InAlN/GaN HEMT devices exhibit serious short-channel effects,which are characterized by difficulty in turn-off,poor gate control ability,threshold voltage drift,and the obvious increase of subthreshold swing.Meanwhile,the traditional InAlN/GaN HEMT devices suffer from severe off-state leakage due to poor electron confinement.The introduction of a BGaN buffer layer with 1.5%(mole fraction)boron is beneficial for InAlN/GaN HEMT devices to maintain good DC performances at high temperatures.When the temperature reaches 500 K,the threshold voltage of InAlN/GaN/BGaN HEMT is always about-3.2 V,the subthreshold swing is 366 mV/dec,the off-state drain current is 3μA/mm,and the off-state power dissipation is 45μW/mm,which are much better than that of the traditional InAlN/GaN HEMT.In addition,compared with the conventional InAlN/GaN HEMT,the peak transconductance and saturation drain current of InAlN/GaN/BGaN HEMT are slightly lower.However,the difference between the two devices gradually decreases with increasing temperature.