Simulating the Source of Polarization Charge in AlGaN/GaN HFETs
Polarization-induced charges at the AlGaN/GaN interface of heterojunction field-effect transistors (HFETs) create a high density, two-dimensional electron gas (2DEG) in the channel. One approach to simulating the 2DEG is to place a fixed positive charge at the AlGaN/GaN interface, thus attracting a fixed quantity of electrons to the channel. Silvaco’s ATLAS software can do this with either an INTERFACE statement or automatically with the use of the POLARIZATION parameter on the REGION statement. This is fine, as far as it goes, but this simple approach glosses over some nuances having to do with the source of carriers in the channel. A paper by Ibbetson, et al.,[1] explored this question theoretically and experimentally.