STRUCTURAL AND ELECTRICAL-PROPERTIES OF REACTIVELY SPUTTERED INN THIN-FILMS ON ALN-BUFFERED (00.1) SAPPHIRE SUBSTRATES - DEPENDENCE ON BUFFER AND FILM GROWTH TEMPERATURES AND THICKNESSES

An extensive investigation of InN overlayers on AlN-buffered (00.1) sa pphire by reactive magnetron sputtering has been undertaken and the de pendencies of several basic materials properties (film thickness, deve lopment and quality of heteroepitaxy, film morphology, and electrical transport) on such key deposition parameters such as the growth temper atures of the insulating AlN buffer layer and the InN overlayer and th eir thicknesses have been determined. Three prominent effects of the A lN buffer layer are (1) the stabilization of heteroepitaxial growth ov er a broad range of film and buffer layer growth temperatures; (2) the attainment of a higher Hall mobility (up to 60 cm2/V s) over much of the same range; and, (3) the retention of heteroepitaxial growth, high er Hall mobility, and pseudo-two-dimensional growth even in the limit of an InN layer of approximately 40 angstrom. In the context of a stru cture-zone model, the AlN buffer layer is projected to effectively rai se the growth temperature of the InN thin film. The increase in effect ive growth temperature is, however, insufficient to overcome low atomi c and cluster mobility and to achieve single-crystal InN thin film gro wth.