Synthesis and epitaxial growth of CdTe films by neutral and ionized beams

The growth of CdTe thin films has been studied by epitaxial processes on the cleavage surface of rock salt in vacuum, using electron microscopic and electron diffraction techniques. The crystallinity and structure of the films depend largely upon the intensities and species of the incident beams. The use of two beams effused separately from the Knudsen cells resulted in the growth of films of good crystallinity when the intensity ratio N_Cd : N_Te was 10 : 1. The epitaxial relationships were studied over the range of substrate temperatures between room temperature and 350°C. The co-existence of α-hexagonal and β-cubic modifications of CdTe and their proportions in the film were revealed as a function of the growth processes and substrate temperature. If two beams were ionized by electron bombardment inside the cells and were incident upon the substrate by applying a dc voltage between source and substrate, the epitaxial temperature can be lowered to near room temperature, giving good epitaxy. The epitaxial relationships in the CdTe/NaCl system have been studied.