Growth and physical properties of Ga2O3 thin films on GaAs(001) substrate by molecular-beam epitaxy

We report effusive evaporation of Ga2O3 thin films on GaAs(001) substrates in a production-type molecular-beam epitaxy system. A polycrystalline Ga2O3 charge heated in a high-temperature effusion cell is used as the evaporation source. The Ga2O3–GaAs structures are characterized by atomic force microscopy (AFM), Rutherford backscattering spectroscopy (RBS), ellipsometry, and transmission electron microscopy (TEM). The Ga2O3 films are amorphous and stoichiometric by transmission electron diffraction and RBS, respectively. Under optimal growth conditions, the Ga2O3 film surface has a typical roughness of 2–3 Å as revealed by AFM, while the Ga2O3–GaAs interface is atomically abrupt as confirmed by the cross-sectional TEM. Such amorphous and stoichiometric Ga2O3 oxide paves the way for GaAs gate dielectrics applications.