Current Status of thin film HgCdTe: Relationship of Structure and Chemistry to Device Application

Abstract

This paper addresses the current status of thin film HgCdTe and limitations in the currently achievable thin film properties. The emphasis is placed on Hg_1−xCd_xTe since this material is presently most seriously considered for infrared devices and particularly resistant to high quality film preparation due to large elemental vapor pressure differences. The current status of thin film HgCdTe is reviewed and the various thin film deposition techniques utilized to prepare HgCdTe thin films are compared. Finally, results are reviewed which still support the claim.that the less investigated technique of bias-sputtering, modified to accommodate deposition in a high partial pressure background of Hg vapor, can yield structurally high quality Hg_1−xCd_xTe films with device-worthy properties. Significant is the fact that the deposition process still provides the simple and systematic control over all relevant film properties without post-deposition treatment. Such control is required to achieve the desired material for device application. As is also reviewed here, this work was one of the first to demonstrate the ability to use low cost foreign substrates for HgCdTe thin film device fabrication.