GdN (1 1 1) heteroepitaxy on GaN (0 0 0 1) by N2 plasma and NH3 molecular beam epitaxy

We report on the heteroepitaxial growth of thin films of rocksalt GdN on c-plane (0 0 0 1) wurtzite GaN by molecular beam epitaxy (MBE) using either an N2 plasma or NH3 as the nitrogen source. In both cases, epitaxial films with fully oriented GdN (1 1 1)∥GaN (0 0 0 1) were deposited as demonstrated by θ–2θ X-ray diffraction. φ scans of GdN peaks demonstrate 6-fold symmetry along the growth axis implying the presence of two 3-fold-symmetric GdN (1 1 1) crystal variants in-plane. Electrical transport and magnetometry measurements on films grown using N2 plasma show that these GdN films are ferromagnetic below TC=70 K and degenerately doped or metallic from 10 to 300 K with magnetotransport signatures associated with TC.