Enhanced green emission from Er-doped (AlGa)₂O₃ films grown by pulsed laser deposition

Erbium (Er) doped (AlGa)₂O₃ films were deposited on sapphire substrates using pulsed laser deposition. The transmittance spectra and X-ray photoelectron spectroscopy measurements show that transparent (AlGa)₂O₃:Er films with a wider bandgap can be achieved by increasing the Al content in the targets. All films exhibit the strongest pure green emission at 550 nm with the wavelength independent of the alloy compositions. A maximum intensity observed at Al content of 0.34 is several times higher than that in Ga₂O₃:Er films, indicating that the intensity of green emission can be enhanced by increasing the host bandgap. Our study also reveals that too high Al content has decreased the photoluminescence intensity, which should be related to the degraded crystallinity proved by X-ray rocking curve. These results suggest that (AlGa)₂O₃:Er film is a promising material for fabricating efficient green luminescent devices.