Electronic transport properties in AlInGaN/AlGaN heterostructures

The AlGaN-channel III-N heterostructure effect transistor (HFET) devices with high breakdown voltage and acceptable on-resistance has shown great potential for next generation of power switching. The electronic transport property of two-dimensional electron gases (2DEGs) in AlInGaN/AlGaN heterostructures is investigated for the first time, and the effects of the alloy disorder scattering from both the barrier layer and the channel layer are analyzed. The quaternary alloy composition dependences of the 2DEG density and mobility and the sheet resistance (positively proportional to the device on-resistance) are studied in nearly lattice matched AlInGaN/Al_0.2Ga_0.8N heterostructures. The alloy composition ranges of the Al_xIn_yGa_1-x-yN barrier layer of 0.58 ≤ x ≤ 0.76 and 0 ≤ y ≤ 0.14 is found to be optimal in all aspects, which corresponds to the threshold voltage of -1.55 ∝ -6.24 V for an AlInGaN/Al_0.2Ga_0.8N HFET with a nickel gate. Moreover, the temperature dependence of 2DEG mobility in lattice-matched AlInGaN/AlGaN heterostructures is discussed with various scattering models. The results show that the magnitudes of the mobility in the sample Al_0.3In_0.05Ga_0.65N/Al_0.05Ga_0.95N, Al_0.5In_0.06Ga_0.44N/Al_0.2Ga_0.8N, and Al_0.8In_0.06Ga_0.14N/Al_0.5Ga_0.5N heterostructures reduces by 61%, 47%, and 37% with the temperature increasing from 300 to 600 K. Our research may provide some instructions for the application of AlInGaN/AlGaN heterojunction to high voltage power devices. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)