Room-temperature epitaxial growth of GaN on conductive substrates

Abstract

We have grown GaN films on (Mn,Zn)Fe2O4 (111) substrates by pulsed-laser deposition at room temperature and investigated their structural properties using reflection high-energy electron diffraction, atomic force microscopy, grazing-incidence x-ray reflectivity, and grazing-incidence x-ray diffraction (GIXD). We have found that GaN (0001) grows epitaxially even at room temperature. The room-temperature growth of GaN starts with the two-dimensional mode followed by the three-dimensional mode, which indicates that the precursors of GaN have large energy enough to migrate on the surface. GIXD measurements showed that the in-plane epitaxial relationship is GaN [11-20] // (Mn,Zn)Fe2O4 [01-1] and approximately 90% of the lattice mismatch is released at the interface. These results indicate that the present technique solves one of the two major problems with epitaxial growth of GaN (mismatch in the thermal expansion coefficients) and alleviates the other problem (mismatch in the lattice constants).