EPITAXIAL-GROWTH OF ALUMINUM NITRIDE LAYERS ON SI(111) AT HIGH-TEMPERATURE AND FOR DIFFERENT THICKNESSES

We present the epitaxial growth by rf reactive sputtering of aluminum nitride on Si(111) at high temperature. The grain size of the obtained films was sufficient to obtain a good low energy electron diffraction (LEED) pattern from which we determined a lattice parameter of 3.1 An gstrom, indicative of fully relaxed films. The surface of the film was examined in situ by Auger electron spectroscopy (AES); no contaminati on was detected, with the exception of low levels of oxygen. The film and its interface were studied by high resolution electron energy loss spectroscopy (HREELS), x-ray photoelectron spectroscopy (XPS) depth p rofiling, and transmission electron microscopy (TEM). Again, a low con centration of oxygen and no carbon contamination were detected by XPS. Three different growth methods were applied to the deposition of alum inum nitride at high temperature. The obtained films were studied in o rder to determine the influence of the methods on the interface, on th e 'bulk structure' of the him, and on its surface. Each has been shown to have particular characteristics. The first one, performed at a tem perature of 1000 degrees C, and including a cleaning of the surface by exposure to Al flux, was characterized by an interfacial layer with n o long-range order and increasing the interaction between the film and the substrate. The second growth consisting of deposition at the same high temperature has shown a good surface quality for very thin layer s (<50 Angstrom) and the absence of an interfacial layer. The last met hod, based on a first step of growth at low temperature (700 degrees C ), resulted in good quality thick layers which allowed us to determine the infrared dielectric constants of aluminum nitride by HREELS.