一种具有双异质结的氮化镓高压肖特基二极管

A GaN-Based High Voltage Schottky Barrier Diode with Double Heterojunction

基于GaN/AlGaN/GaN-on-Si材料,研制了一种高压低功耗新型肖特基二极管(SBD)。由于异质结的极化效应,在AlGaN/GaN界面会产生高浓度的二维电子气(2DEG),在GaN/AlGaN界面产生二维空穴气(2DHG)。首先,在正向阻断时,随着偏压的升高,2DEG和2DHG被完全耗尽,在界面处留下固定的正/负极化电荷而构成极化结,电力线从正电荷指向负电荷,使得漂移区内的电场分布较均匀,提高了二极管的击穿电压。其次,肖特基二极管的阳极GaN/AlGaN层被完全刻蚀,获得了低的开启电压。最后,开发了低损伤ICP刻蚀工艺,降低了肖特基接触界面的缺陷,减小了反向泄漏电流和开启电压。实验结果表明,二极管的击穿电压为1109V@1mA/mm,开户电压为0.68V,比导通电阻为1.17mΩ·cm^(2),Baliga FOM值为1051MW/cm^(2)。该SBD兼具高击穿电压和低开启电压的特点,均匀性好。

A novel high voltage and low power Schottky barrier diode(SBD)with double-heterojunction was theoretically and experimentally investigated on the GaN/AlGaN/GaN/Si substrate.Owing to the polarization effect,the two-dimensional hole gas(2DHG)and electron gas(2DEG)were formed at the GaN-top/AlGaN and AlGaN/GaN interface,respectively.Firstly,with the increase of bias voltage,the 2DHG and 2DEG gas were completely exhausted,leaving a fixed positive/negative polarization charge at the interface to form a polarization junction.The power lines shifted from positive charge to negative charge,which made the distribution of the electric field in the drift area more uniform,and improved the breakdown voltage of the diode.Secondly,the GaN/AlGaN layer of the Schottky diode was completely etched to obtain a low turn-on voltage.Finally,a low damage ICP etching process was developed to reduce the defects of the Schottky contact interface,and to reduce the reverse leakage current and turn-on voltage.The experimental results showed that the breakdown voltage of the diode was 1109V@1mA/mm,the turn-on voltage was 0.68V,the specific on-resistance was 1.17mΩ·cm^(2),and the Baliga FOM value was 1051MW/cm^(2).The SBD had the characteristics of high breakdown voltage,low turn-on voltage and good uniformity.