The effect of interface roughness scattering on low field mobility of 2D electron gas in GaN/AlGaN heterostructure

We report the results of our experimental and theoretical studies concerning the temperature dependence of electron mobility in a two dimensional electron gas (2DEG) confined at the GaN/AlGaN interface. Experimental mobility of about 850cm(2)/V s at 3.8 K remains almost constant up to lattice temperature T-L = 45 K, it then decreases rapidly down to about 170 cm(2)/V s at TL = 300 K. The results are discussed using a theoretical model that takes into account the most important scattering mechanisms contributing to determine the mobility of electrons in 2DEG. We show that the polar optical phonoD scattering is the dominant mechanism at high temperatures and the acoustic deformation potential and piezoelectric scatterings are dominant at the intermediate temperatures. At low temperatures, the Hall mobility is confined by both the interface roughness (IFR) and ionised impurity scattering. The correlation length (Lambda) and lateral size (Delta) of roughness at the GaN/AlGaN heterointerface have been determined by fitting best to our lowtemperature experimental data. (C) 2004 Elsevier B.V. All rights reserved.