Wide bandgap engineering of (AlGa)2O3 films

TLDR

Pulsed laser deposition on sapphire was used to grow (AlGa)₂O₃ films, and X‑ray photoelectron spectroscopy of core‑level inelastic loss onset was shown to accurately determine their bandgaps, agreeing with transmittance measurements. The films exhibit high transmittance, Al composition matching the targets, and a bandgap that rises continuously from about 5 to 7 eV with increasing Al, demonstrating PLD as a viable technique for bandgap‑tunable (AlGa)₂O₃.

Abstract

Bandgap tunable (AlGa)2O3 films were deposited on sapphire substrates by pulsed laser deposition (PLD). The deposited films are of high transmittance as measured by spectrophotometer. The Al content in films is almost the same as that in targets. The measurement of bandgap energies by examining the onset of inelastic energy loss in core-level atomic spectra using X-ray photoelectron spectroscopy is proved to be valid for determining the bandgap of (AlGa)2O3 films as it is in good agreement with the bandgap values from transmittance spectra. The measured bandgap of (AlGa)2O3 films increases continuously with the Al content covering the whole Al content range from about 5 to 7 eV, indicating PLD is a promising growth technology for growing bandgap tunable (AlGa)2O3 films.