Optical and magnetic properties of GaN epilayers implanted with ytterbium

We have studied the optical and magnetic properties of ytterbium implanted GaN epilayer grown on (0001) sapphire by metalorganic chemical vapor by deposition (MOCVD). Samples were implanted at room temperature with Yb ions at dose 4 1015 cm-2 and energy of 150 keV. The implanted samples were annealed at 1000 C in N2 at atmospheric pressure to recover implantation damages. The photoluminescence (PL), PL excitation (PLE), and PL kinetics have been studied with continuous and pulse photo-excitations in 360-1100 nm spectral range at different temperatures. The characteristic Yb3+ ion emission spectra were observed in the spectral range between 970-1050 nm. Theoretical fittings of the experimental PL temperature and PL kinetics data suggest that Yb3+ ions are involved in at least two major luminescence centers. The PLE spectra indicate that excitation of the Yb3+ ion occurs via electron-hole pair generation and complex processes. Magnetization versus magnetic field curves shows an enhancement of magnetic order for Yb-implanted samples in 5 K to 300 K temperature range. The Yb-implanted GaN sample showing weak ferromagnetic behavior was compared with the ferromagnetic in situ doped GaYbN material.