LATERAL SUPPLY MECHANISMS IN SELECTIVE METALORGANIC CHEMICAL VAPOR-DEPOSITION

Selective epitaxial growth of GaAs was carried out by atmospheric-pressure metalorganic chemical vapor deposition, and lateral supply mechanisms of reactant species from mask areas to window areas were investigated. Since reactant species arriving on SiO2 surfaces were easily reevaporated, deviation from mass balance was observed. In the case of a SiO2 mask with width of more than 20 mum, lateral vapor-phase diffusion dominated over increment of selective epilayers because of short surface-diffusion length on SiO2 surfaces (< 1 mum). It was apparent experimentally and analytically that long ridged tails of selective epilayers were formed by lateral vapor-phase diffusion. Appearance of wavelike tails at mask edges was due to surface diffusion from (111)B facets. Surface-diffusion length on (111)B surfaces was estimated at 3 mum.