Dependence of process damage on GaN channel thickness in AlGaN/GaN high-electron-mobility transistors with back-barrier layers

In this study, AlGaN/GaN high-electron-mobility transistors with 65 and 38 nm channel layers and back-barrier layers were fabricated. The isolation process resulted in damage related to the thickness of the channel layer, which deteriorated properties such as sheet resistance R (sh) and transconductance g(m). These were attributed to the surface oxidation of the AlGaN barrier, and the simulation results showed that the channel layer thickness changed the dependence of R (sh) on the trap level density; however, the calculated changes were smaller than the observed changes. In the range of gate lengths we produced, suppression of the short-channel effect by the back barrier layer was confirmed. However, no significant change in the channel layer thickness was observed.