Crystal Growth and Orientation of Vacuum Deposited Films of CdTe

Thick films of CdTe were deposited on amorphous quartz plates at normal and oblique incidences in vacuum, and their oriented growth was studied by X-ray diffraction and by electronmicroscope observation. It was found that fibrous crystallites having the [111] growth axis inclined to the incident beam. Lamellae structure normal to the fiber axis was visualized on etching or cleaving. The crystallographic polarity along the [111] direction of thick CdTe films deposited on amorphous quartz as well as some other substances was determined from a measurement of the piezoelectric effect of the films; the substrate side of most films was the Cd(111) plane and the film surface side was the Te(111) plane. The photovoltaic effect of vacuum-deposited films was discussed in terms of the crystallographic characteristics such as the polarity and the cubic-hexagonal transition.