Observation of quantum oscillations in triethylaluminum-enabled low-temperature MOCVD-grown β -(Al x Ga1− x )2O3/ β -Ga2O3 2DEGs

We report the observation of Shubnikov–de Haas (SdH) oscillations in metalorganic chemical vapor deposition (MOCVD)-grown (010)-oriented β-(AlxGa1−x)2O3/β-Ga2O3 modulation δ-doped heterostructures. Triethylgallium (TEGa) and triethylaluminum (TEAl) were used as precursors, which enabled the growth to occur at a relatively low substrate temperature of 650 °C. The as-grown films exhibit sub-nanometer roughness and show distinct Laue oscillations, confirming a high-quality, sharp heterointerface. Additionally, we report the highest β-(AlxGa1−x)2O3/β-Ga2O3 two-dimensional electron gas (2DEG) low-temperature mobility to date of 2914 cm2/Vs at 45 K. From the SdH oscillations below 10 K, we extract a 2DEG density of 1.7×1012 cm−2, a cyclotron effective mass of 0.305±0.007 me, a quantum scattering time of 178±11 fs, and an estimated effective g-factor of 3.1. The effective mass is in reasonable agreement with the calculated conduction band non-parabolicity in β-Ga2O3 given the estimated position of the Fermi level above the conduction band minimum. Temperature-dependent transport is further analyzed to determine that background and remote ionized impurity scattering are the likely dominant scattering mechanisms at low temperatures. This work affirms the viability of MOCVD using TEAl and TEGa for growing high-quality gallium oxide-based heterostructures.