HIGH-QUALITY EPITAXIAL SI FILMS ONTO GAMMA-AL2O3(111) SI(111) SUBSTRATES USING AL PREDEPOSITION LAYERS/

Very flat epitaxial Si(111) films with high crystalline quality were g rown using thin Al layers deposited onto gamma-Al2O3 (111)/Si (111) su bstrates at room temperature, prior to the growth of Si films by Si2H6 gas source molecular beam epitaxy. Epitaxial Si layers grown with a 1 0-Angstrom-thick Al predeposition layers showed 7X7 streaked reflectio n high-energy electron diffraction patterns and a mirrorlike surface. The epitaxial Si layer had a significantly improved crystalline qualit y and surface morphology comparable to that grown without the Al prede position layer. The optimum Al thickness for a high quality Si film wa s 5-10 Angstrom, even though the thickness was varied from 0 to 25 Ang strom. The Al deposited surface was changed to an Al-O surface (rather than a metallic Al layer) just before Si growth at 800 degrees C, and a decrease in the incubation time was observed for an Al thickness of 5-10 Angstrom. It is believed that a modification of the Al2O3 surfac e occurs, which results in improved crystalline quality of Si films gr own on the Al2O3. (C) 1996 American Institute of Physics.