Defect reduction for interdiffused mercury cadmium telluride based infrared detector materials

摘要

This invention reduces the dislocation defect density in variable badgap HgCdTe based infrared absorbing materials formed by Metal Organic Chemical Vapour Deposition Interdiffusion Multilayer Process (MOCVD_IPM), which conventionally includes annealing alternatively deposited thin layers of HgTe and CdTe. The present invention comprises firstly depositing a buffer layer 22 upon a CdTe based substrate 20 and incorporating Se into sequentially deposited CdTe layers 32, 34, 36, 38 in order to lattice match them with the HgTe layers 24, 26, 28, 30. The homogenous detector materials 42 thus formed is HgCdSeTe. Alloy compositions formed after the anneal process may be varied, thus varying the wavelengths absorbed, by changing the relative thickness of the CdTeSe layers deposited. A similar process can be carried out using HgTe and lattice matched CdZnTe layers. The materials may be formed into detectors with more than one layer of annealed alloy in order to be able to detect long, medium and short wavelength infrared radiation.