Mercury Cadmium Telluride is a type of thermal camera sensor. MCT sensors are a type of cooled thermal sensor with low SWAP characteristics.
The Low SWAP nature of these sensors has made them a top pick among space agencies. Where payload weight is critical.
Missions such as the James Webb Space Telescope (JWST) and the famous Hubble Deep Space Telescope both use MCT sensor arrays.
The unique properties of MCT or HgCdTe make them tunable in the Midwave-Infrared Wavelength Range of 2.0 - 5.4 µm.
A downside of MCT sensors is that they must be Cryogenically cooled. However, they do not have to be cooled as much as InSb sensors.