Origin of compositional modulation of InGaAs in selective area metalorganic vapor phase epitaxy

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Abstract
We investigated the in-plane compositional modulation of InGaAs epilayers in selective area metalorganic vapor phase epitaxy using a stagnant layer model. The growth pressure dependence of selective area growth of InAs and GaAs constituents using trimethylindium and triethylgallium revealed that the origin of the compositional modulation is in the mask region. A larger escaping probability of desorbed Ga source materials from the mask surface to the fluid layer and a slightly larger sticking coefficient defined at the mask surface of Ga source materials enrich the In composition of InGaAs epilayers near the mask edge. The escape probability is determined by the length ratio of the vapor phase mean-free path of source materials to the stagnant layer thickness. The finite sticking coefficient at the mask surface corresponds to a chemical reaction which produces nonreactive species. With the larger escape probability of Ga source materials and the introduction of finite sticking coefficients at the mask surface, we successfully quantitatively predicted the experimental results.