介质膜性质及表面处理对GaN HEMT特性的影响

Effect of Dielectric and Surface Treating on the Characteristic of GaN HEMT

GaN HEMT器件经过钝化后,抑制电流崩塌效应明显,但同时产生其他负面效应,为了改善目前GaN HEMT钝化后漏电增加和击穿电压减小等情况,研究了钝化技术对GaN HEMT电流特性的影响,包括介质膜应力、折射率和表面预处理与器件饱和电流、电流崩塌量的关系,优化了表面预处理和钝化工艺条件。实验效果在GaN HEMT电特性上的改善明显。结果表明,采用折射率为2.1～2.2的SiN钝化膜,饱和电流密度增加到1100mA/mm,电流崩塌量小于10%,肖特基接触反向偏压为-20V时泄漏电流达10-5A数量级。

It is obvious that the current collapse is restrained after the passivation of GaN HEMT devices. But passivation also has some negative influences on the performance of devices. In order to solve the problems on the increase of leakage current and decrease of break-down voltage after SiN passivation, the effects of surface passivation on the characteristic of GaN HEMT were studied, including the effect of the dielectric film, index of refraction, surface pretreatment on the saturation current and current collapse, the condition of surface pretreatment and passivation were optimized. The experimental results show obvious improvement in the characteristic of GaN HEMT, it indicates that the saturation current density increases to 1 100 mA/mm, the current collapse is less than 10%, the leakage current is 10^-5 A when the Schottky reverse voltage was - 20 V, the refraction index of SiN film is 2.1-2.2.