Defect Passivation for Improved Material Properties in Ga-free and Ga-based SLS

A collaboration between Amethyst Research Inc., University Multispectral Laboratories (a government-owned, contractor-operated nonprofit corporation), and Teledyne Imaging Systems (a large defense contractor) proposes to develop/improve high-performance infrared sensors based on Type II, strained-layer superlattices (SLS). Such sensors offer (theoretical) advantages over state-of-the-art HgCdTe photodiodes including greater sensitivity, improved manufacturability, and lower cost. However, the performance of SLS devices is limited by defects that decrease carrier lifetimes and cause high leakage currents. The proposed program will target resolution of these problems by hydrogen passivation of defects to mitigate their deleterious effects. Hydrogenation will be evaluated over a wide range a variety of SLS structures and devices. SLS structures include both traditional Ga-based ones, as well as Ga-free materials that have recently shown much promise, i.e. over an order-of-magnitude improvement in carrier mobility. Amethyst"s hydrogenation techniques has achieved two important results that form the basis for the present proposal, i.e. an increase in SLS carrier lifetimes by>20 and a two-fold increase in the integrated photoluminescence (PL) intensity, which provides a measure of the material quality. These results are preliminary and not yet optimized, and will be thoroughly investigated and extended in the proposed program.