The evolution of nanostructure morphology and local chemical environment during hetero-epitaxial growth of aluminium selenide on Si(111) was investigated using scanning tunnelling microscopy and high-resolution photo-emission spectroscopy. Despite the strong similarity to GaSe in atomic and electronic structure during deposition of the first AlSe bilayer, subsequent growth was quite different; resulting in an alternating Al-Se-Al-Se stacking sequence consistent with defected-wurtzite-structure Al2Se3. The first bilayer was completed on a given terrace before the second layer nucleated, but subsequent layers nucleated before completion of the second layer. The surfaces of well-formed AlxSey islands were smooth, and terminated by Se atoms; Al then stuck before additional Se, resulting in rougher incomplete islands with Al-rich disordered surfaces. Growth with extra Al in the incident flux did not result in layered AlSe and induced only subtle differences in film morphology.

Heteroepitaxial Growth of the Intrinsic Vacancy Semiconductor Al2Se3 on Si(111) - Initial Structure and Morphology. C.Y.Lu, J.A.Adams, Q.Yu, T.Ohta, M.A.Olmstead, F.S.Ohuchi: Physical Review B, 2008, 78[7], 075321 (6pp)