Minority Carrier Lifetime Measurements in Strained Layer Superlattices

Type II strained layer superlattice (SLS) p-n diode arrays fabricated on domestic-source GaSb substrates are a promising route to meet the critical need within DoD for large area, large format array infrared detectors. However, current SLS material quality is limiting detector performance. A quantitative, cost effective and trusted evaluation technique for measuring the SLS minority carrier lifetime is critical to establishing a comprehensive development program for the SLS system. In Phase I we will develop an automated, variable temperature photoconductance decay (PCD) lifetime measurement system capable of measuring lifetimes in the range of 1 ns (existing SLS materials quality) up to 25 ms (anticipated long-term SLS quality). The system will also permit synergistic use of equipment components to allow various other techniques to be incorporated on a common platform, such as current transient spectroscopy and photo induced current transient spectroscopy. The appropriate combination with PCD lifetime measurements will provide an unprecedented, coordinated technique for materials evaluation. The program brings together teams from Amethyst Research, Texas State University and IntelliEPI. In Phase II a system will be built and fully evaluated to establish a sustainable product platform. The final product will comprise an Integrated Narrow-Bandgap Lifetime Assessment Platform (INLAP).