Characterization and Reduction of Elcetrically Active Defects in Type II SLS Detector Materials

Maxion Technologies proposes to adopt and further develop a metrology system tailored to understanding the nature of electrically active trap states in type-II SLS IR detector materials, and demonstrate the utility of the technique as a tool for MBE material optimization. Capacitance transient spectroscopy (CTS) is a unique diagnostic technique in that it directly measures the properties of electrically active traps such as their concentration, capture and emission rates, activation energies, and it also distinguishes between majority- and minority-carrier trap types. It is spectroscopic in the sense that it can resolve the signatures from multiple traps within the same material. CTS has proven to be a powerful diagnostic tool for mature semiconductor materials such as Si, GaAs, InP, etc., but it has not been effectively utilized for type-II SLS IR detector materials. CTS has the potential to significantly improve the ability to relate device growth processes directly to the generation of defects that contribute to high dark current and limit photogenerated carrier lifetime. We will use CTS to quantify type-II SLS material quality and subsequently improve detector material quality by better understanding the nature of the defect states and their relation to MBE growth parameters and SLS interface layer treatments.