MOLECULAR LAYER EPITAXY BY REAL-TIME OPTICAL PROCESS MONITORING

In this paper we consider modern methods of optical process monitoring and control in the context of atomic layer epitaxy. One specific meth od, p-polarized reflectance spectroscopy (PRS), is chosen to assess de tails of layer-by-layer growth. We show that PRS monitoring under cond itions of steady-state growth by pulsed chemical beam epitaxy (PCBE) c an achieve the deposition of molecular layers of GaP on silicon (100) deposited with a precision of 5%, which can be improved by reducing th e growth rate and increasing the period of time averaging of the refle ctance data. Since in the nucleation period prior to formation of a co ntiguous heteroepitaxial film inhomogeneous surface chemistry and roug hening complicates the modeling of the overgrowth process, advances in both experimental methods and theory are required for extending the c ontrol to non-steady-state growth conditions. Results of simultaneous single-wavelength PR monitoring and laser light scattering measurement s in conjunction with atomic force microscopy studies of short period heteroepitaxial overgrowth processes are presented. The extension of P RS to the monitoring of organometallic chemical vapor deposition at hi gher pressures is also discussed.