Mercury Zinc Telluride 10.6 µm Ambient Temperature Photodetectors

Theoretical and experimental investigations of mercury zinc telluride (MZT) ambient temperature longwavelength photodetectors are reported. The ultimate detectivities of MZT photoconductors (PC), photodiodes, photoelectromagnetic (PEM) and Dember detectors at 10.6 μm have been calculated as a function of material composition, doping and geometry of the devices. The high-temperature longwavelength PC and PEM detectors have been fabricated from Cu-doped bulk MZT crystals grown by a modified quench/anneal technique. The measured performance has been confronted with theoretical predictions showing good overall agreement. It is concluded that the high figure of merit, stability and hardness of MZT make this material superior in comparison to mercury cadmium telluride and that it will replace the latter in application for high-temperature photodetectors. The performance of high-temperature MZT photodetectors can be further improved by the use of optical resonant cavity and optical immersion. These devices exhibit detectivity by several orders of magnitude higher than thermal detectors with subnanosecond response time, and can achieve performance comparable to that of slow thermal detectors.