Molecular-beam-epitaxy growth of CdTe on InSb (110) monitored <i>in situ</i> by Raman spectroscopy

Abstract

CdTe epitaxial layers were deposited on clean cleaved InSb(110) substrates by molecular-beam epitaxy at room temperature and elevated temperatures. The formation of interface and layer was investigated using Raman spectroscopy as a growth monitor, i.e., Raman spectra were taken on line without interruption of the deposition process. Fabry–Pérot interference of the incident as well as the scattered light within the heterostructure leads to a characteristic modulation of the substrate phonon scattering intensity. The modulation is calculated and serves as a measure for the layer thickness. For the deposition at elevated temperatures the true surface temperature is determined from the InSb TO phonon frequency shift. While at a substrate temperature of 150 °C the crystalline quality of the CdTe layer was improved compared to room-temperature growth, the deposition of CdTe at 300 °C resulted in the formation of a layer consisting of In2Te3 and liberated Sb. The effect of the laser radiation on the growth process at different temperatures is also discussed.