【Epitaxy Papers】X-ray photoelectron spectroscopy and photoluminescence study of copper and magnesium doped beta-phase Ga₂O₃

      Researchers from the University of California have published a dissertation titled "X-ray photoelectron spectroscopy and photoluminescence study of copper and magnesium doped beta-phase Ga₂O₃" in Applied Physics Letters.

Abstract

      Magnesium (Mg) doped, copper (Cu) doped, and Mg and Cu co-doped β-Ga₂O₃ thin film samples were grown on c-plane sapphire substrates using plasma-assisted molecular beam epitaxy. X-ray photoelectron spectroscopy analysis confirmed the doping concentrations. In addition, changes in the valence band density of states near the valence band maximum were revealed, while no Fermi-level shifts were observed in all doped samples, suggesting no electrical conductivity change compared to the undoped sample. Room-temperature photoluminescence (PL) characterization using an ArF laser of 193 nm excitation and subsequent PL peak deconvolution were performed. No near-band edge emissions were observed. The PL in each sample is dominated by optical transitions between the conduction band and self-trapped hole levels, and donor–acceptor pair transitions. These donors and acceptors originate from oxygen vacancies (V_O) and gallium–oxygen vacancy complexes (V_Ga–V_O), respectively. No visible transitions assignable to Mg and Cu acceptor levels could be extracted.

DOI：

https://doi.org/10.1063/5.0322948