Determination of the in-plane effective mass and quantum lifetime of 2D electrons in AlGaN/GaN based HEMTs

Magnetoresistance and Hall resistance measurements have been used to investigate the electronic transport properties of AlGaN/GaN based HEMTs. The Shubnikov-de Haas (SdH) oscillations from magnetoresistance, is obtained by fitting the nonoscillatory component to a polynomial of second degree, and then subtracting it from the raw experimental data. It is shown that only first subband is occupied with electrons. The two-dimensional (2D) carrier density and the Fermi energy with respect to subband energy (E-F-E-1) have been determined from the periods of the SdH oscillations. The in-plane effective mass (m*) and the quantum lifetime (tau(q)) of electrons have been obtained from the temperature and magnetic field dependencies of the SdH amplitude, respectively. The in-plane effective mass of 2D electrons is in the range between 0.19 m(0) and 0.22 m(0). Our results for in-plane effective mass are in good agreement with those reported in the literature. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim