Uniform growth of GaAs by MOCVD on multi-wafers

Abstract

The thickness of the stagnant layer observed by smoke gas simulator is correlated to that of the epitaxial layer of GaAs. With this knowledge we developed an atmospheric pressure MOCVD system with a barrel reactor for large area epitaxial growth of GaAs and GaAlAs. The susceptor is a hexagonal frustum in shape, on which six 2 inch diameter wafers are set. It was known that the tapering angle of the susceptor and the number of its revolutions affect uniformity in the thickness of epitaxial layer. Under the optimized growth conditions, variation of layer thickness in a wafer was less than ± 5%. Variation of average layer thickness of a wafer was less than ± 2% in a run and that of six wafers in a run was less than ±2% from run to run. In S-doping by using H 2S, the uniformity of carrier concentration depended on growth temperature and [AsH 3]/[TMGa] ratio. Under the optimized growth conditions, variation of the carrier concentration in a wafer, the average carrier concentration of a wafer in a run and that of six wafers in a run from run to run were less than ±5%.