Analysis of Deposition Selectivity in Selective Epitaxy of GaAs by Metalorganic Chemical Vapor Deposition

Publisher Website
Google Scholar
Abstract
In GaAs-selective epitaxy by atmospheric-pressure MOCVD using W and SiO2 masks, the observed difference of the deposition conditions can be explained by two different mechanisms of heterogeneous nucleations (HN) on the mask surfaces. One is HN on ideally flat mask areas (case I), and the other is HN at irregular nuclei on the mask surfaces (case II). Surface concentration of reactant species on masks is analyzed by applying the surface-diffusion model to reactant species on the masks, and, for case I, the calculated results of polycrystal deposition on W and on SiO2 masks are compared with experimental ones. It becomes apparent that the occurrence of the thick polycrystal deposition frequently observed on W masks is due to high surface concentration. Products of the surface-diffusion coefficient and the stagnantlayer thickness are estimated as 6.25 cm3/s for W masks and 169.5 cm3/s for SiO2 masks at 610°C.