Observation of thermal desorption and MBE growth rate using laser light scattering

Abstract

We applied Laser Light Scattering (LLS) to study oxide surface desorption on InSb substrates, and the subsequent growth of CdTe layers by molecular beam epitaxy. LLS measurements allowed us to determine the critical temperature before surface degradation of InSb, which is not clearly noticed by Reflection High Energy Electron Diffraction (RHEED). Surface defects appeared on substrates where this temperature was exceeded, as observed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). During the MBE growth of CdTe on InSb, two features were noticed in LLS measurements. First, a decrease in intensity was observed that can be associated to a change in surface roughness at the initial stages of growth. The second feature is an oscillatory behavior, which can be related to interference. A geometrical model of interference in thin films was used to calculate the layer thickness in real time.