REAL-TIME MONITORING OF HETEROEPITAXIAL GROWTH-PROCESSES ON THE SILICON(001) SURFACE BY P-POLARIZED REFLECTANCE SPECTROSCOPY

In this paper we describe the real-time monitoring by p-polarized refl ectance spectroscopy (PRS) using pulsed chemical beam epitaxy (PCBE) o f GaxIn1-xP on Si(001) as an example. For constant source vapor pulse height, width and repetition rate, the formation of the heteroepitaxia l film on the Si(001) surface proceeds via a three-dimensional nucleat ion and overgrowth mechanism. Provision of a high initial supersaturat ion of the surface drives the nucleation kinetics toward a two-dimensi onal mechanism. The analysis of the fine structure in the PRS intensit y reveals that under the conditions of quasi-steady state growth the s urface chemistry cycles between enhanced and diminished P-activity and diminished and enhanced Ga-activity, with the dealkylation of the gro up III alkyl source molecules constituting a rate limiting step in the growth kinetics. Since the deposition rate per precursor pulse cycle can be determined experimentally, molecular layer epitaxy conditions c an be imposed and verified in real-time without reliance on a self-lim iting growth mechanism.