2D Simulations of Current-voltage Characteristics of Cubic Al x Ga 1-x N/GaN Modulation Doped Hetero-junction Field Effect Transistor Structures

We report on calculations of the current-voltage characteristics of cubic AlxGa 1-xN/ GaN modulat ion doped hetero-junction field effect transistors using two-dimensional nextnano 3 device simu lation software. Specifically, we investigate the influence of the thickness and the background doping concentration of cubic GaN buffer on the output and transfer characteristics of the device. Also, the influence of Al content and the effect of a δ-doped layer inserted in the AlxGa 1-xN are discussed. We find that the maximu m saturation current is shown by a structure with a δ-doped layer of n = 6 x 10 18 cm -3 , Al content of x = 25% and a GaN buffer layer thickness of 100 n m. For this structure, our calculat ions show a low threshold voltage value and the highest transconductance gm among the samp le structure that we used for our calculations.