Microscopic Defects and Infrared Absorption in Cadmium Telluride

The correlation observed in CdTe between microscopic defects and the infrared absorption at 10.6 μm is reported. The data were obtained from transmission electron microscopy, scanning electron microscopy, infrared and optical microscopy, spectrophotometry, and laser calorimetry. For chlorine and indium doped samples it was determined that increasing the concentrations of In2Te3 and CdCl2 precipitate platelets subsequently increases the 10.6 μm infrared absorption coefficient in CdTe. Isolated dislocations, dislocation networks, tellurium precipitates, vacancy loops, and stacking faults were also shown to exercise an important influence on infrared absorption. Localized regions of defect aggregations in many samples were found to be responsible for the macroscopicabsorption sites typically observed by infrared microscopy. The significant differences between the present data and previously reported macroscopic defect models are discussed.