Selective area metal-organic vapour phase epitaxy (SA-MOVPE) growth of compound semiconductor, such as In1–xGaxAsyP1–y, was an indispensable technology to realize one-step fabrication of monolithic optical integrated circuits (OEICs). In SA-MOVPE, the growth rate of unmasked region was enhanced, because unreacted group III precursors on the mask region diffuse into the epitaxial growth region. This growth rate enhancement was mainly caused by the gas-phase diffusion of precursors, but the contribution of surface diffusion became larger as the unmasked stripe became narrower. Moreover, in the SA-MOVPE growth of InP, the abnormal growth near the mask edge and the formation of tear-drop-like hillocks, which was considered to be originated from surface diffusion, were observed. The role of surface diffusion during the SA-MOVPE growth of InP was investigated here by measuring the cross-sectional area of abnormal growth and surface roughness. By changing the growth temperature from 793 to 883K, the area of abnormal growth increased and took maxima at 823K, and decreased again at higher temperatures. The concentration of group III precursor enhanced the abnormal growth and the roughness. The concentration effect was larger than the first order, and its relation to the surface diffusion length was suggested. This information on surface diffusion during SA-MOVPE was a key factor for the precise control of SA-MOVPE growth.

Role of Surface Diffusion during Selective Area MOVPE Growth of InP. N.Waki, T.Nakano, M.Sugiyma, Y.Nakano, Y.Shimogaki: Thin Solid Films, 2006, 498[1-2], 163-6