Analytical Expression of Barrier Layer for Enhancement Mode AlGaN/GaN HEMT

In this paper, we have investigated analytically the required thickness of barrier layer for the enhancement mode of AlGaN/GaN high electron mobility transistor (HEMT). A mathematical expression is derived for barrier layer of AlGaN/GaN high electron mobility transistor (HEMT) so that the device can work in enhancement mode. This critical value of barrier layer is fixed for a particular Al composition, gate barrier height and relaxation factor. The device will work in enhancement mode if the barrier layer thickness is below the critical value. This critical value of barrier layer is a function of polarization charge. It is seen from derived result that critical value of barrier layer increases if the polarized charge is reduced. Threshold voltage is calculated to show the dependence of critical barrier layer thickness and the gate barrier height.