Study of the effects of barrier and passivation nitride stresses on AlGaN/GaN HEMT performance using TCAD simulation

Using TCAD simulation, we studied the stress effect of pseudomorphically grown Al_0.25Ga_0.75N barrier and passivation nitride with intrinsic stress on the electrical characteristics of AlGaN/GaN HEMT. It is found that barrier stress can reduce the two-dimensional electron gas (2DEG) by as much as 15% and change the current by more than 10%, depending on the deformation potential values. Therefore, it is important to extract accurate conduction band deformation potential from experiment or first principle calculation. It is also found that the stress by passivation nitride will induce substantial piezoelectric (PE) charge under the gate region and can be used to adjust the pinch-off voltage through stress engineering for short gate length device.