Variation of the effective extinction coefficient during pyrolytic and photo-assisted II-VI MOVPE growth, measured by in situ laser interferometry

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Abstract
In situ laser reflectometry has been used to monitor the growth of II-VI semiconductor materials under pyrolytic and photo-assisted conditions. The fit of effective extinction coefficient, , at each peak and trough in the growth interferograms showed that different growth modes are dominant under pyrolytic and photo-assisted conditions. The fit of for several single layers of ZnTe grown under pyrolytic conditions indicated an overall good quality epitaxial growth, with layer quality increasing with layer thickness, whereas for layers grown with photo-assistance, for the same growth temperatures and precursor mixtures, the fit of was anomalously high. In situ monitoring of these layers revealed that they begin to roughen after a maximum of of film deposition. Thus the anomalously high values for would seem to indicate that this fit of is revealing insights into the degradation of film growth for these layers. Through post-growth spectral reflectance analysis of a thin epilayer of ZnSe, where the fringes due to variations in film thickness are clearly visible, an argument for the increase in based on non-linear growth rate across the surface under photo-assisted conditions is presented.