AlGaN背势垒对SiC衬底AlN/GaN HEMT器件的影响

Influence of AlGaN Back Barrier on AlN/GaN HEMTs on SiC Substrate

利用相同器件工艺在两种不同材料结构上制备了Al N/Ga N高电子迁移率晶体管(HEMT),研究了Al Ga N背势垒结构对器件特性的影响。测试结果表明,有背势垒结构的器件最大饱和电流密度和峰值跨导要小于无背势垒结构器件,栅压偏置为+1 V时,无背势垒的Al N/Ga N HEMT器件最大饱和电流密度为1.02 A·mm-1,峰值跨导为304 m S·mm-1,有背势垒结构的器件饱和电流密度为0.75 A·mm-1,峰值跨导为252 m S·mm-1。有背势垒结构器件的亚阈值斜率为136 m V/dec,击穿电压为78 V;无背势垒结构器件的亚阈值斜率为150 m V/dec,击穿电压为64 V。栅长为0.25μm有背势垒结构的器件电流截止频率高于无背势垒结构器件,最高振荡频率要低于无背势垒结构的器件。

The Al N / Ga N high electron mobility transistors（ HEMTs） with different material structures were fabricated using the same device process. The influences of Al Ga N back barriers on the characteristics of the devices were studied. The test results show that the maximum saturation current density and the peak-transconductance of the device with Al Ga N back barrier are lower than those of the device without Al Ga N back barrier. When the gate voltage bias is 1 V,the Al N / Ga N HEMTs without Al Ga N back barrier show a maximum drain current density of 1. 02 A·mm- 1and the peak-transconductance of304 m S·mm- 1,while the Al N/Ga N HEMTs with Al Ga N back barrier show a maximum drain current density of 0. 75 A·mm- 1and the peak-transconductance of 252 m S ·mm- 1. The device with Al Ga N back barrier shows subthreshold slope of 136 m V / dec and a breakdown voltage of 78 V,while the device without Al Ga N back barrier shows a subthreshold slope of 150 m V / dec and a breakdown voltage of 64 V.For a 0. 25 mm gate length,the device with Al Ga N back barrier shows higher current cut-off frequency and lower maximum oscillation frequency than that of the device without Al Ga N back barrier.