Epitaxy of Si nanocrystals by molecular beam epitaxy on a crystalline insulator LaAlO3(0 0 1)

Abstract We have studied the Si initial growth mechanisms on LaAlO 3 (0 0 1), a crystalline oxide with a high dielectric constant ( high-κ material). The clean LaAlO 3 (0 0 1) substrate exhibits a c (2×2) reconstruction that can be attributed to surface O vacancies. Si deposit by molecular beam epitaxy was studied as a function of both deposition temperature and thickness. Epitaxy was obtained only above 550 °C. In this case, a Volmer–Weber mode is observed. The associated nanodots are relaxed and formed by pure Si as ascertained by the Si 2 s XPS peak, which remains for 1 and 10 ML at the binding energy corresponding to Si–Si bonds. Moreover the islands have an abrupt interface with the LaAlO 3 (0 0 1) substrate without the formation of silicate or silica. A unique epitaxial relationship between LaAlO 3 and the crystallized Si islands is pointed out by RHEED and confirmed by HRTEM, where the Si(0 0 1) planes are parallel to the LaAlO 3 (0 0 1) ones, but rotated by 45° in the [0 0 1] direction. This orientation leads to mismatch and strain minimization of the Si film.