REAL-TIME OPTICAL MONITORING OF EPITAXIAL-GROWTH - PULSED CHEMICAL BEAM EPITAXY OF GAP AND INP HOMOEPITAXY AND HETEROEPITAXY ON SI

We present a study of the real-time monitoring of the homoepitaxial gr owth of GaP, InP, and the growth of InP/GaP and GaP/Si(001) heterostru ctures, combining single wavelength p-polarized reflectance (PRS), ref lectance-difference spectroscopy (RDS), and laser light scattering (LL S) during pulsed chemical beam epitaxy with tertiarybutylphosphine, tr iethylgallium, and trimethylindium sources. The growth rate and the bu lk optical properties are revealed by PRS with submonolayer resolution over 1000 Angstrom of film growth. The surface topography is monitore d by LLS providing additional information on the evolution of the surf ace roughness as well as the nucleation/growth mechanism. The optical surface anisotropy, which is related to surface reconstruction and/or surface morphology,. is monitored by RDS and compared with the results of PRS and LLS. The results are discussed with respect to the deposit ion kinetics, in particular as a function of the V:III flux ratio. The pulsed supply of chemical precursors causes a periodic alteration of the surface composition, which is observed as correlated periodic chan ges in the RD and PR signals, confirming the high sensitivity of both methods to surface chemistry.