Influence of GaN Cap Layer on the Performance of AlGaN/GaN HEMT

The impact of GaN cap layer on the performance metrics of GaN/AlGaN/AIN/GaN high electron mobility transistor (HEMT) is extensively examined through TCAD environment. The inherent material nature of both piezoelectric along with spontaneous polarization in GaN usually results in the formation of 2-D electron gas (2-DEG) demonstrating high electron density in the GaN channel. Furthermore, a thin GaN cap layer can influence the device performance by further enhancing the electron mobility from $1315 \mathrm{~cm}^{2} / \mathrm{V}$-s to $1425 \mathrm{~cm}^{2} / \mathrm{V}$-s with cap layer and modulating the field that leads to an increase in the drain current from 0.36 A to 0.58 A. Hence, the GaN cap can be harnessed appropriately towards the applications in power electronics as well as in Radio Frequency (RF) applications.