Growth of epitaxial AlN(0001) on Si(111) by reactive magnetron sputter deposition

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Abstract
2H–AlN(0001) layers have been grown on Si(111) by reactive magnetron sputtering from an Al target in Ar+N2 gas mixtures at temperatures Ts=400–900 °C. Variations in reactive gas consumption, target voltage, and current–voltage characteristics versus nitrogen partial pressure were used to determine deposition parameters required to yield stoichiometric AlN with growth rates ≥2 μm h−1. High-resolution cross-sectional transmission electron microscopy (XTEM) analyses of films grown at 900 °C showed that the initial 6–8 monolayers were (111)-oriented cubic 3C before transforming to the (0001)-oriented 2H polytype. The epitaxial relationship was found by XTEM and x-ray diffraction (XRD) to be 2H–AlN(0001)//3C–AlN(111)//Si(111) with 2H–AlN[12̄10]//3C–AlN[110]//Si[110]. High-resolution XRD ω−2Θ and ω rocking curve widths for films grown at Ts=900 °C were 70 and 500 arc sec, respectively, the lowest values yet reported.