Structural and magnetic characterization of Sm-doped GaN grown by plasma-assisted molecular beam epitaxy

We have investigated structural, optical and magnetic properties of Sm-doped GaN thin films grown by plasma-assisted molecular beam epitaxy. Reflection high-energy electron diffraction and X-ray diffraction reveal that Ga1-xSmxN films with a SmN mole fraction of similar to 8% or below are grown on GaN templates without segregation of any secondary phases. With increasing SmN mole fraction, the c-axis lattice parameter of the GaSmN films linearly increases. GaSmN films with low Sm concentrations exhibit inner-4f transitions of Sm3+ in photoluminescence spectra. The present findings show that Sm atoms are substituted for some Ga atoms as trivalent ions (Sm3+). The Ga1-xSmxN films display hysteresis loops in magnetization versus external magnetic field (M-H) curves even at 300 K. We will discuss the origin of these features together with the corresponding temperature dependences of magnetization. (C) 2016 The Japan Society of Applied Physics