An Intensive Study on Assorted Substrates Suitable for High JFOM AlGaN/GaN HEMT

Abstract

The performance comparison and the temperature profile of AlGaN/GaN HEMT on different substrates are investigated. It results the maximum drain-source current (IDS) of 1.08 A/mm, 1.04 A/mm, 0.81 A/mm and 0.669 A/mm for AlGaN/GaN HEMT on Diamond, Sapphire, Silicon Carbide and Silicon substrates respectively. In addition, it contributes the breakdown voltage of 62 V, 100.4 V, 174 V and 298 V for Sapphire, Diamond, Silicon and Silicon Carbide based HEMT respectively. It also exhibits the maximum current gain cut off frequency of 17.4 GHz, 25 GHz, 45.91 GHz and 47.07 GHz for the HEMT grown on SiC, Silicon, Sapphire and Diamond substrates respectively. The trade off between the breakdown voltage and the cut-off frequency is observed in all HEMT devices. Hence, the Johnson figure of merit (fT × BVGD) is calculated to inspect the choice of substrate for AlGaN/GaN HEMT device. Furthermore, the simulation result reveals very high Johnson figure of merit for the HEMT grown on Silicon Carbide substrate (5.18 × 1012 V/s), than Sapphire (2.84 × 1012 V/s), Silicon (4.35 × 1012 V/s) and Diamond (4.72 × 1012 V/s) based HEMT devices. Hence, the SiC based HEMT will be a trend for future high power and high frequency applications.