Shubnikov–de Haas oscillations of 2DEGs in coherently strained AlN/GaN/AlN heterostructures on bulk AlN substrates

Abstract

We report the observation of Shubnikov–de Haas (SdH) oscillations of two-dimensional electron gases (2DEGs) in coherently strained, low-dislocation undoped and δ-doped AlN/GaN/AlN heterostructures on bulk AlN. The oscillations reveal a single subband occupation in the undoped and two subband occupation in the δ-doped sample. More importantly, SdH oscillations enable direct measurement of critical 2DEG parameters at the Fermi level: carrier density and ground state energy level, electron effective mass (m*≈0.289 me for undoped and m*≈0.298 me for δ-doped sample), and quantum scattering time (τq≈83.4 fs for undoped and τq≈130.6 fs for δ-doped sample). These findings provide important insights into the fundamental properties of 2DEGs that are quantum confined in the thin GaN layers, essential for designing nitride heterostructures for high-performance electronic applications.