Real-time optical monitoring of heteroepitaxial growth processes on Si under pulsed chemical beam epitaxy conditions

For an understanding of the surface chemistry and defect formation during the initial nucleation period and heteroepitaxial overgrowth process, real-time methods with sub-monolayer resolution are essential. We present results of a combined study of p-polarized reflectance (PRS), reflectance difference spectroscopy (RDS), and laser light scattering (LLS) during the growth of GaP on Si by pulsed chemical beam epitaxy (PCBE) with tertiarybutylphosphine, triethylgallium, and trimethylindium precursors. The pulsed supply of chemical precursors causes a periodic alteration of a surface reaction layer, which is observed as periodic fine structure in the PR and RD transients. This fine structure is used to study the nucleation and overgrowth process with submonolayer resolution. Both, PRS and RDS, show changes in the initial nucleation period, which are related to the three-dimensional nucleation process. The surface reaction kinetics for the precursors is studied under quasi-steady-state growth conditions.