Al2O3绝缘层的AlGaN/GaN MOSHEMT器件研究

Study of AlGaN/GaN MOSHEMT device with Al_2O_3 insulating film

在研制AlGaN/GaNHEMT器件的基础上,采用ALD法制备了Al2O3AlGaN/GaNMOSHEMT器件.通过X射线光电子能谱测试表明在AlGaN/GaN异质结材料上成功淀积了Al2O3薄膜.根据对HEMT和MOSHEMT器件肖特基电容、器件输出以及转移特性的测试进行分析发现:所制备的Al2O3薄膜与AlGaN外延层间界面态密度较小,因而MOSHEMT器件呈现出较好的栅控性能;其次,该器件的栅压可以加至+3V,此时的最大饱和电流达到800mA/mm,远远高于肖特基栅HEMT器件的最大输出电流;而且栅漏反偏状态下的泄漏电流却减小了两个数量级,提高了器件的击穿电压,通过进一步分析认为泄漏电流主要来源于Fowler-Nordheim隧穿.

On the basis of AlGaN/GaN HEMT, the A1GaN/GaN MOSHEMT device was fabricated with Al2O3 insulating film for the first which was deposited by ALD. The X-ray photoelectron spectroscopy measurements showed successful deposition of Al2O3 layer on the AlGaN/GaN film. The results of Schottky capacitance, I-V characteristics and DC transfer characteristics measurement showed that the interface state density between the AlGaN film and the Al2O3 insulating film was fairly low and the MOSHEMT device showed successful gate control of drain current up to VGs = ＋ 3 V and achieved drain saturation current of 800 mA/mm, which was much larger than that of the HEMT device. Furthermore, the gate leakage current of MOSHEMT is two orders lower in the reverse bias condition as compared with the Schottky gate structure, which increased the device breakdown voltage, while the leakage current was governed by the Fowler-Nordheim tunneling mechanism.