Infrared Photodetectors: Mercury Cadmium Telluride Technology

This lecture discusses the technology behind Mercury Cadmium Telluride (MCT) photoconductors, which require cooling to 77 Kelvin for optimal sensitivity at 10 micron wavelengths. The instructor explains the significance of this wavelength, as it corresponds to the maximum emission of black body radiation at room temperature. The lecture covers the design of cameras utilizing MCT photodiodes, highlighting their capability to form large pixel matrices, such as 4000 by 4000 pixels. The structure of p-n junctions in MCT is detailed, including the use of indium bumps for low-temperature contact and the integration of silicon readout electronics. The flip-chip assembly method is introduced, which allows for the combination of infrared sensors with silicon CMOS technology. The lecture also touches on the evolution of infrared photodiode technology, mentioning the development of megapixel cameras and the potential of Quantum Well Infrared Photo Detectors as a future solution. Overall, the lecture provides a comprehensive overview of MCT photoconductors and their applications in infrared detection.