Atomic layer deposition of atomic mirror for silicon

Abstract

There have been significant progresses in atom optics utilizing laser cooling techniques in recent years. Among them, we have been interested in an atomic mirror for silicon which can reflect silicon atoms. The atomic mirror consists of two layers on a sapphire substrate, and then atoms are reflected by the dipole forces from evanescent waves caused by the light reflected internally and totally at the interface of different refractive indices. In this study, we have constructed some structures of the atomic mirror. We tried atomic layer deposition techniques for preparation of both Al₂O₃ and TiO₂ thin films, whose surface and interface roughnesses are well suppressed. In order to achieve the predicted enhancement of the evanescent waves, atomic layer deposition of the layer with the higher refractive index is especially important. It has found that absorption can be suppressed considerably by adding Al(CH₃)₃ precursor gas to the alternate introducing cycle of TiCl₄ and H₂O₂ precursor gases. We use this effect which can improve homogeneity and flatness of layers significantly, to design an atomic mirror using atomic layer deposition.