Discovery of variable band gap Hg1-xCdxTe(HgCdTe)ternary alloy in 1959 by Lawson and co workers,triggered 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 temperature.