Barrier infrared detectors

In 1959, Lawson and co-workers publication triggered development of variable band gap Hg1-xCdxTe (HgCdTe) alloys providing an unprecedented degree of freedom in infrared detector design. Over the five decades, this material system has successfully fought off major challenges from different material systems, but despite that it has more competitors today than ever before. It is interesting however, that none of these competitors can compete in terms of fundamental properties. They may promise to be more manufacturable, but never to provide higher performance or, with the exception of thermal detectors, to operate at higher temperatures. In the last two decades a several new concepts of photodetectors to improve their performance have been proposed including trapping detectors, barrier detectors, unipolar barrier photodiodes, and multistage detectors. This paper describes the present status of infrared barrier detectors. It is especially addressed to the group of III-V compounds including type-II superlattice materials, although HgCdTe barrier detectors are also included. It seems to be clear that certain of these solutions have merged as a real competitions of HgCdTe photodetectors.