Wide bandgap engineering of (AlGa)₂O₃ films

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.