Vol. 35, Issue 3, pp. 597-604

Abstract

The Ga, Al and In nitrides (A^III–N) are complete material system suitable in high power and high temperature electronic devices such as Al_xGa_1–xN/GaN heterostructure field effect transistor (HFET). The examples of computer modelling of A^III–N heterostructures were shown. A^III–N materials exhibit strong piezoelectric and spontaneous polarization. The computer modelling results showing the influence of layer polarity on carrier distribution in Al_xGa_1–xN/GaN heterostructure were shown. Only in Ga-faced heterostructures 2-dimensional electron gas (2DEG) is formed. The effect of Al_xGa_1–xN layer relaxation on 2DEG concentration in Al_xGa_1–xN/GaN heterostructure was examined. The difference in spontaneous polarization in Al_xGa_1–xN and GaN caused high 2DEG concentration even in Al_xGa_1–xN/GaN heterostructures with relaxed Al_xGa_1–xN layer. Polarization field in Al_xGa_1–xN layer in Al_xGa_1–xN/GaN heterostructure was enough for achieving high 2DEG concentrations in undoped heterostructure. Strained Al_xGa_1–xN layer was introduced into typical HFET heterostructure. GaN layer above an interlayer was depleted and the negative influence of using non semi-insulating GaN layer in HFET transistor was reduced.