A solution for channel electron migration in normally-off MIS-HEMT with buried fluorine ions

Abstract

High electron mobility transistors based on Gallium Nitride are promising devices for high frequency and high-power applications. While switching applications demand normally-off operation, conventional HEMTs possess a channel populated with electrons at zero gate voltage making them normally-on. By implanting fluorine below the channel, normally-off operation can be achieved. However, at high gate voltages, a drop in the transconductance is obtained due to electron migration from the AlGaN/GaN interface to the insulator/AlGaN interface. In this work, to recover the drop in the transconductance and hence increase the current density, an AlN interlayer is introduced between the AlGaN and GaN layers to block electron migration.