Effect of growth conditions on Eu3+ luminescence in GaN

Eu-doped GaN thin films were in situ grown on sapphire substrates by RF plasma-assisted solid-source molecular beam epitaxy technique. Strong red emission at ∼622 nm from 5D0–7F2 radiative transitions in Eu3+ ions was observed for all samples. The effects of important growth parameters, such as III/V ratio (Ga flux), Eu cell temperature (Eu flux) and growth temperature, on Eu3+ photoluminescence were studied. X-ray diffraction and secondary ion mass spectroscopy measurements were performed to investigate thin film quality and Eu doping profiles. The strongest Eu3+ luminescence was obtained from GaN:Eu thin films grown under slightly N-rich condition (III/V<1), while the highest Eu3+ emission efficiency was obtained in thin films grown under Ga-rich condition (III/V≥1). The optimum Eu doping concentration for Eu3+ luminescence is ∼(0.1–1.0) at% for III/V≤1 ratio condition. Higher growth temperature (>750 °C) was also found to enhance Eu3+ luminescence intensity and efficiency.