The effect of barrier layers on 2D electron effective mass in Al0.3Ga0.7N/AlN/GaN heterostructures

Abstract

The Shubnikov de Haas (SdH) effect measurements have been performed to evaluate the influence of Si3N4 passivation, a spacer layer, and Si-doped barrier layer on the electronic transport parameters of two-dimensional (2D) electrons in Al0.3Ga0.7N/AlN/GaN heterostructures under temperatures from 1.8 K to 40 K and at a magnetic field up to 11 T. The 2D electron effective mass (m*), 2D carrier density (N 2D), the difference between Fermi level and subband energy levels (E F − E 1), quantum lifetime (τ q) are determined by analyzing SdH oscillations. Although investigated samples with equal 2D electron density are examined, the effective mass values of 2D electrons are deduced within the range of (0.16 ± 0.005)m 0 and (0.23 ± 0.005)m 0. Results reveal that passivation, a spacer layer, and doping affect 2D electron effective mass. Furthermore, the dominant scattering mechanisms that limited electron transport is determined as a long-range scattering for all investigated sample. The results obtained provide information for the high-performance device application of these samples.