Task 1: Theoretical and Experimental Study of Defects

Task Leader: David Smith (ASU)

Theoretical studies have indicated that T2SL-based LWIR devices can have similar, if not superior performance compared to the traditional HgCdTe (MCT). However, T2SL materials have yet to demonstrate carrier lifetimes as long as 1 us, which have been observed in MCT. High densities of point/line defects, interfacial traps, and surface states have been identified as the underlying causes for lower lifetimes and poor performance. To further improve the quality and performance, a study of defect formation and their impact on low-bandgap applications such as T2SL IR detectors. To this end, we will investigate the following:

• The origins of defects and their impacts on performance, via innovative theoretical modeling;
• An experimental study of the structural properties of defects and interfacial structure;
• Optical measurements to study surface states and defects.

 InAs/InAsSb T2SL in a MWIR laser structure (Images taken by Smith, ASU.) revealing very high quality of the materials (YH Zhang, ASU)