Room-Temperature Epitaxial Growth of GaN on Atomically Flat MgAl_2O_4 Substrates by Pulsed-Laser Deposition

摘要

We have grown GaN films on MgAl_2O_4(111) substrates at room temperature (RT) and investigated the structural properties of the films. The atomically flat surfaces of MgAl_2O_4 with a step and terrace structure are obtained by annealing at 1000℃ in a box made of ceramic MgAl_2O_4. It is found that GaN(0001) grows epitaxially on atomically flat MgAl_2O_4(111) surfaces even at RT. The epitaxial relationship between the GaN epilayer and the MgAl_2O_4 substrate is GaN[1120] // MgAl_2O_4[011]. GaN films have a clear six fold symmetry without 30° rotational domains. The interfacial reaction between GaN and MgAl_2O_4 is completely suppressed in the case of RT growth.