Real-time diagnostics of II-VI molecular beam epitaxy by spectral ellipsometry

Spectral ellipsometry has been applied to in situ diagnostics of Hg1−xCdxTe molecular beam epitaxial growth. Spectral ellipsometry provides surface, composition, and film thickness properties of thin film electronic materials in real-time during growth and processing. This study is discussed in two parts. In the first part, the surface state properties of Hg1−xCdxTe and the substrate material Cd1−xZnxTe were studied under ultrahigh vacuum (UHV) conditions. By measuring the spectral ellipsometric quantities Ψ and Δ versus temperature under UHV conditions, the presence and desorption temperatures of surface species have been determined. Tellurium stabilized Cd1−xZnxTe surfaces were not observed to exhibit any apparent surface changes during heating under these conditions. Oxidized Cd1−xZnxTe surfaces, however, exhibit discontinuities in Ψ and Δ indica-tive of desorption of a surface species in the 300 °C range. Tellurium stabilized Hg1−xCdxTe surfaces also exhibit discontinuities in Ψ and Δ occurring at abo...