Growth and electron microscopy study of GaN/MgAl2O4 heterostructures

✍ Scribed by Li, Guoqiang ;Shih, Shao-Ju ;Fu, Li

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 281 KB
• Volume: 207
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200983642

✦ Synopsis

Abstract

We successfully grew Gallium nitride (GaN) films on MgAl~2~O~4~ (111) substrates using low temperature pulsed laser deposition (PLD). X‐ray diffraction rocking curves revealed the high quality of as‐grown GaN with its full width at half maximum (FWHM) along [0002] as small as 0.08°. Atomic force microscopy images showed very smooth surface of as‐grown GaN and indicated a two‐dimensional growth. High‐resolution transmission electron microscopy showed high structural perfection of GaN films. The crystalline structure for MgAl~2~O~4~ substrate from its body to its top part adjacent to GaN epitaxy kept constant, and the interface between GaN and MgAl~2~O~4~ was atomically abrupt. We attribute the high quality of as‐grown GaN films to the well‐controlled Mg atom evaporation from MgAl~2~O~4~ substrate surface owing to the application of low growth temperature in PLD: on the one hand, it avoids the severe interfacial reaction that is very likely to take place in conventional MOCVD or MBE growth, and hence makes the epitaxial growth possible; on the other hand, it conserves the crystalline structure of the substrate surface, and consequently takes good advantage of the small lattice mismatch between GaN and MgAl~2~O~4~.