The Effect of Growth Temperature On The Microstructure of Movpe AlN/Si (111)

Abstract

AbstractThe epitaxy, defect structure, and heterointerface microstructure of MOVPE-grown AlN on <111> oriented Si were studied by transmission electron microscopy (TEM) in an investigation of the affects of the growth temperature (925°C–1 175°C) on the microstructure of low thickness (∼0.2 μm) films. A film grown at 1175°C was single crystalline with the following orientation relationship: (0001)AlN||(111)Si, <1120> and <1010>AlN||<211>Si. All AlN films grown at temperatures below 1100°C were wire-textured polycrystals with (0001)AlNlargely parallel to (111)siand some in-plane preferred orientation similar to that of 1175°C AlN epifilms. Columnar grains/domains with faceted top surfaces were observed for the entire growth temperature range. The mean column diameters decreased from 50 nm to 35 nm as the growth temperature decreased. The columnar grain/domain structure and the faceted tops resulted in peakto-valley surface roughness on the order of 20 nm. Sharp interfaces of AlN/Si were generally observed in all AIN films studied by HREM except for the 1075°C film where a transitional layer of approximately 15Å thick was observed at some interface regions. Defects typically encountered in large lattice mismatched heteroepitaxial systems were observed.