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31 May 2012 Numerical simulation of InAs/AlAsSb nBn detector arrays
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This paper describes our recent results on three-dimensional (3D) numerical simulations of quantum efficiency and crosstalk in back-illuminated InAs nBn detector arrays. Our 3D simulations reveal that the p-type barrier layer, in the region between adjacent mesas where the n-type collector layer is removed, has a "built-in" potential well for holes, caused by the transfer of electrons from the absorber layer into the barrier layer. This well forms a channel in which holes are "trapped," and where the spatial separation of excess electron-hole pairs inhibits recombination, allowing holes trapped in the channel to diffuse long distances toward the nearest mesa where they are collected in the collector mesa. This mechanism may explain the anomalously long lateral collection lengths for photocarriers measured in nBn detectors with p-type barrier layers that have been reported by two groups. We used our 3D numerical model to confirm the lateral collection behavior of this hole channel in the barrier layer, and to calculate quantum efficiency and crosstalk in a 3×3 back-illuminated nBn array with 15×15 μm2 pixels, with a variety of mesa sizes and diffusion lengths in the absorber layer, and for two mesa geometries, including one in which both the collector and the barrier layer are removed to form the mesa, thereby eliminating the hole channel.
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Jonathan Schuster, Benjamin Pinkie, Marion Reine, and Enrico Bellotti "Numerical simulation of InAs/AlAsSb nBn detector arrays", Proc. SPIE 8353, Infrared Technology and Applications XXXVIII, 835330 (31 May 2012);

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