Growth studies of molecular-beam epitaxial ZnSe using reflection high-energy electron diffraction oscillations

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Abstract
Reflection high‐energy electron diffraction (RHEED) intensity oscillations are often used to investigate in situ the growth of III‐V materials by molecular‐beam epitaxy (MBE). In this work, we have used RHEED oscillations to perform a quantitative study of the growth mechanisms of ZnSe, a II‐VI semiconductor. Our experiments illustrate that the RHEED pattern of ZnSe is far less intense than that of III‐V materials grown by MBE, and no specular spot is observed over a wide range of growth conditions. We have, however, been able to record up to 25 oscillations allowing a quantitative study of the growth of ZnSe by MBE. Thus we have used RHEED oscillations to make an in situ systematic study of the influence of the three main growth parameters (substrate temperature and Zn or Se impinging fluxes) on the ZnSe growth rate. We observed that the variation of the ZnSe growth rate is due to a nonunity sticking coefficient of both Zn and Se species at the interface in the standard growth conditions used. Our observations can be described using a thermodynamic model and enable us to control the desired growth conditions. Our work demonstrates the utility of RHEED oscillations to understand the MBE growth mechanisms of II‐VI compounds.