Influence of doping profile of GaN:Fe buffer layer on the properties of AlGaN/AlN/GaN heterostructures for high-electron mobility transistors

Abstract

The effect of the Fe doping profile of the GaN buffer layer in the heterostructures for high-electron mobility transistors was studied experimentally and by computer simulation. The exponential Fe tail extending to the nominally undoped layers may greatly affect the properties of the structure. Reducing the distance between the channel and the Fe-doped buffer to less than 1 μm results in a decrease in the density and mobility of the two-dimensional electron gas. It also leads to the higher off-state avalanche breakdown voltage and reduced leakage current. A good agreement between simulation and experimental data is obtained when taking into account a Fe segregation effect, while an abrupt doping profile lead to significant discrepancies between them