GdN (111) heteroepitaxy on GaN (0001) by N2 plasma and NH3 molecular beam epitaxy

We report on the heteroepitaxial growth of thin films of rocksalt GdN on c-plane (0001) wurtzite GaN by molecular beam epitaxy (MBE) using either an N-2 plasma or NH3 as the nitrogen source. In both cases, epitaxial films with fully oriented GdN (111)parallel to GaN (0001) were deposited as demonstrated by theta-20 X-ray diffraction. phi scans of GdN peaks demonstrate 6-fold symmetry along the growth axis implying the presence of two 3-fold-symmetric GdN (111) crystal variants in-plane. Electrical transport and magnetometry measurements on films grown using N-2 plasma show that these GdN films are ferromagnetic below T-C=70 K and degenerately doped or metallic from 10 to 300 K with magnetotransport signatures associated with T-C. (C) 2009 Elsevier B.V. All rights reserved.