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 degree s C by plasma source molecular beam epitaxy. Reflection high energy electro n diffraction and transmission electron microscopy studies show that AlN fi lms grown at 400 degrees C form an initial amorphous region at the interfac e, followed by c-axis oriented columnar grains with slightly different tilt s and twists. AlN films grown at 600 degrees C showed a significantly reduc ed 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 defect s such as stacking faults, dislocations, and grain boundaries. (C) 1999 Ame rican Institute of Physics. [S0021-8979(99)00611-8].