Characterization of MOCVD-grown GaAs on Si by spectroscopic ellipsometry

This paper describes the evaluation of the crystalline quality, the stress and surface roughness of GaAs layer grown on Si substrate by using spectroscopic ellipsometry (SE). GaAs layers were grown by metalorganic chemical vapor deposition with changing the intermediate layer and growth conditions. The nine parameters were determined by the fitting of the calculated SE curve to the experiment one, assuming that the structure of surface is (GaAs oxide)/(GaAs + void)/(GaAs layer). It is shown that the tensile stress is applied to 3 μm thick GaAs layer and the stress value is about the same for various intermediate layer structure. However, the surface roughness greatly depends on the intermediate layer structure. The surface roughness of GaAs on Si with AlGaP intermediate layer is smallest, which is consistent with the TEM observation.