Theoretical Study of Electron Confinement in Submicrometer GaN HFETs Using a Thermally Self-Consistent Monte Carlo Method

This paper studies various existing advanced GaN heterostructures, which are introduced to provide better confinement of the 2-D electron gas in the channel using a Monte Carlo simulation method coupled with a 3-D solution of the heat diffusion equation. It is shown that the introduction of acceptors in the buffer layer and the introduction of an InGaN back-barrier layer at the bottom of the channel, in a single heterojunction AlGaN/GaN heterostructure field-effect transistor (HFET), improve charge confinement in the channel. It is also shown how the inclusion of an AlGaN carrier exclusion layer at the AlGaN/GaN interface significantly improves the current-handling capability of the HFET. This paper is also a study of the effect of carrier confinement on the thermal performance of each structure; the results show that better confinement of carriers in the HFET channel is accompanied by an enhancement of the influence of self-heating effects.