Microstructure of low temperature grown AlN thin films on Si(111)

AlN thin films were grown on HF-etched Si(111) substrates at 400-600 degrees C by plasma source molecular beam epitaxy. Reflection high energy electron diffraction and transmission electron microscopy studies show that AlN films grown at 400 degrees C form an initial amorphous region at the interface, followed by c-axis oriented columnar grains with slightly different tilts and twists. AlN films grown at 600 degrees C showed a significantly reduced amorphous region near the interface promoting an epitaxial growth of AlN with AlN[0001]parallel to Si[111] and AlN[01 (1) over bar 0]parallel to Si[11 (2) over bar] orientations. However, all the films show numerous defects such as stacking faults, dislocations, and grain boundaries. (C) 1999 American Institute of Physics. [S0021-8979(99)00611-8].