Various methods have been used to initiategrowth by Molecular Beam Epitaxy (MBE) of GaN onsapphire, or other substrates, but there is always a problemwith morphology and with a high defect density which resultsin the formation of a sub-grain boundary structure. We showthat by using, homo-epitaxial growth on properly preparedbulk GaN substrates, combined with high temperature growth,we obtain a significant improvement in surface morphology.Growth at sufficiently high temperature leads to a rapidsmoothing of the surface and to almost atomically flat surfacesover relatively large areas. Multi-Quantum Well structuresgrown on such GaN epitaxial films are dislocation free with abrupt interfaces.
展开▼
