LAUSR

In this work, high-performance high-electron-mobility transistors (HEMTs) with a thin GaN channel and an AlN back barrier were fabricated and investigated in detail. The AlN back barrier HEMTs possess a higher current density and a better linearity than traditional devices. In addition, the off-state leakage current of the AlN back barrier HEMTs is more than one order of magnitude lower than that of traditional devices with a high-resistance Fe-doped GaN buffer, even though they do not involve any intentional doping technique. Additionally, the high-temperature performance of the AlN back barrier HEMTs is excellent, with less attenuation in the drain current density and less increase in the off-state leakage current. Moreover, the breakdown voltage of the AlN back barrier HEMTs is as high as 309 V with an LGD of 2.5  μm, resulting in a high Baliga figure of merit of 0.354 GW/cm2. The superior performance of the AlN back barrier devices is further demonstrated by the calculation and simulation results. The results in this work not only show the great potential of AlN back barrier HEMTs but also provide a useful direction for overcoming the limiting issues of nitride devices.