Direct growth of crystalline spinel GaON films: A wide-bandgap mixed-anion semiconductor
Mixed-anion semiconductors offer opportunities for bandgap engineering beyond conventional multication alloys, but competing phases and disorder complicate their synthesis and the identification of their electronic properties. Gallium oxynitride (GaON) could connect the technologically important GaN and Ga2O3 systems, yet establishing a clear relation between its crystal structure, composition and bandgap remains challenging. Here we report the direct growth of crystalline spinel gamma-GaON films by nitrogen-plasma-assisted pulsed-laser deposition. Varying the nitrogen and oxygen supply yields monoclinic beta-Ga2O3, predominantly disordered films and crystalline spinel GaON. Complementary diffraction, atomic-resolution microscopy and elemental analysis establish the spinel structure and nitrogen incorporation. Temperature-dependent photocurrent spectroscopy reveals a clear redshift of the crystalline gamma-GaON response, supporting assignment of a band-edge transition near 4.3 eV at room temperature. These results open opportunities to investigate mixed-anion wide-bandgap semiconductor physics and develop heterostructures.