Influence of multiple conduction channels on MISHEMT's intrinsic voltage gain

Abstract

The influence of multiple channels of Si3N4/ AlGaN/ AlN/ GaN Metal-Insulator-Semiconductor High Electron Mobility Transistor (MISHEMT) were analyzed focusing mainly on the transistor's analog performance. In order to better understand the contribution of each channel conduction, the gate length, source/drain electrodes depth and source/drain distance to the gate electrode were varied. The total drain current is composed by 3 different components, where two of them are related to HEMT conduction and one is related to MOS conduction. Due to their different nature and distance to the gate electrode, each channel conduction exhibits different threshold voltages, causing unusual transfer and output characteristics. As a result, the MISHEMTs present an unexpected increase in intrinsic voltage gain (Av) for higher gate bias (strong conduction). The HEMT conduction is responsible for sustaining drain current levels so high that it affects the Early voltage more strongly than the degradation of gD, ensuring a high Av value.