Advanced Infrared (IR) Sensor Components for Missile Defense

The objective of this proposal is to further explore PbSnSe detector array on Si substrate. Two approaches are proposed. One is a zero-risk incremental advance that employs a new growth condition to reduce the dislocation density. Another approach is a novel fabrication technique with high-risk but it could enable revolutionary rather than evolutionary advances. IV-VI semiconductors such as Pb1-xSnxSe can be grown epitaxially on Si substrate with a fluoride buffer layer. Monolithic mid-IR detector arrays have been fabricated on Si substrate with read-out integrated circuit and shown promising performance. The main advantages of IV-VI Pb-salt semiconductors include: (1) the large dielectric constant helps screen and localize the defect related effects. (2) The uniformity of the epitaxial material and thus the cutoff wavelength is high. This reduces the demand for powerful signal processing ROIC. (3) The low growth temperature allows direct growth of Pb-salt detector structure on Si with ROIC. Therefore, a cost-effective, monolithic FPA can be fabricated on Si substrate. Two-color simultaneous waveband operation and large formats of FPA can also be fabricated.