A New Methodology to Investigate the Effect of Stress and Bias on 2DEG and Drain Current of AlGaN/GaN Based Heterostructure

The effect of negative, neutral and positive stress by Si3N4 film on AlGaN layer of AlGaN/GaN based high electron mobility transistor (HEMT) heterostructure has been investigated by varying different stress values using Synopsys Sentaurus device simulation. This paper shows a relation between the stresses of passivation layer, two dimensional electron gas (2DEG) formed at the interface of AlGaN/GaN region and respective drain current. The increase in negative stress will result in the increase of 2DEG density, which will result in the increase of drain current. Additionally, the 2DEG density was found to be depended on the applied bias voltage, showing the higher drain sweep voltage will increase the 2DEG density. This study also provides the effect of stress on direct-current (DC) capacitance-voltage characteristics of device electrical performance. It suggests that the capacitance will be increased with the increasing positive stress, indicating the change in interface states due to stress effect.