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Type-II Superlattice Based Infrared Detectors
Type-II Superlattice Based Infrared Detectors

Date: Monday, March 7, 2011
Time: 4:00 PM
Location: 125 Steele, Caltech
Speaker: David Ting

Kavli Nanoscience Institute / Microdevices Lab (KNI-MDL) Seminar


Remarkable progress has been achieved in the antimonide-based superlattices since the analysis by Smith and Mailhiot in 1987 first pointed out their advantages for infrared detection. In the long wavelength infrared (LWIR), type-II InAs/Ga(In)Sb superlattices have been shown theoretically to have reduced Auger recombination and suppressed band-to-band tunneling. Suppressed tunneling in turn allows for higher doping in the absorber, which has led to reduced diffusion dark current. The versatility of the antimonide material system, with the availability of three different types of band offsets, provides great flexibility in device design. Heterostructure designs that make effective use of unipolar barriers have demonstrated strong reduction of G-R dark current. As a result, the dark current performance of antimonide superlattice based single element LWIR detectors is now approaching that of the state-of-the-art MCT detector. To date, the antimonide superlattices still have relatively short carrier lifetimes; this issue needs to be resolved before type-II superlattice infrared detectors can achieve their true potential. The antimonide material system has relatively good mechanical robustness when compared to II-VI materials; therefore FPAs based on type-II superlattices have potential advantages in manufacturability. Improvements in substrate quality and size, and reliable surface leakage current suppression methods, such as those based on robust surface passivation or effective use of unipolar barriers, could lead to high-performance large-format LWIR focal plane arrays.

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