In situ reflection anisotropy spectroscopy analysis of heteroepitaxial GaP films grown on Si(100)

In situ reflection anisotropy spectroscopy (RAS)/reflection difference spectroscopy was applied as a quantitative probe of antiphase domains in heteroepitaxial films deposited on Si(100). The in situ probe was deduced from the spectroscopic signature of the P-rich, homoepitaxial GaP(100) surface and its well-established atomic reconstruction via a comparative investigation using RAS (homoepitaxial versus heteroepitaxial). For that, we determined changes in temperature, surface reconstruction, atomic order, and excess phosphorus on the surface of the homoepitaxial GaP(100) samples to specifically change the RA spectra in terms of shape and intensity. According to the presence of antiphase disorder a linear reduction in the RAS signal occurred. In addition, RA spectra of the heteroepitaxially prepared GaP/Si(100) films contained characteristic deviations from RA spectra of homoepitaxial GaP(100). They originated from reflections at the additional GaP/Si(100) heterointerface. Simple interference affecting the normalization of the RAS signal was found as a major source of the deviations and, thus, corresponding corrections were applied in the RA spectra. At photon energies around 3.2 eV, the correction even amplified the difference between the spectra of GaP/Si(100) and GaP(100) samples. This indicated an additional optical anisotropy induced by the interface reflection which peaked in the range of the determined spectral position. (C) 2010 American Institute of Physics. [doi:10.1063/1.3357391]