Luminescence studies of erbium-doped gallium nitride

The GaN thin film was grown on a sapphire substrate using low pressure metal organic chemical vapor deposition from triethyl-gallium and ammonia at 1050°C. Both Er and oxygen were implanted to a concentration of approximately 10²⁰ cm^-3. Oxygen bonding puts the Er in a 3+ state, which is necessary for luminescence. Following implantation, the GaN:Er was annealed at 900°C for one hour in an ammonia atmosphere. The wafer was then placed in a cryogenic cathodoluminescence (CL) measurement system and cooled to 5 K. The electron beam was 15 kV at 20 μA. A prism spectrometer with a lead sulphide (PbS) detector, chopper, and lock-in amplifier was used to find the 1.5 μm luminescence signal. A photomultiplier was used for the UV-visible part of the spectrum. Cathodoluminescence spectrum of Er³⁺ doped GaN is presented and discussed.