From Event: SPIE Optical Engineering + Applications, 2017
We present a model for the spectral external quantum efficiency (EQE) to extract the minority carrier diffusion length (Ln) of a unipolar nBp InAs/GaSb Type-II superlattice (T2SL) mid-wave infrared (MWIR) detector. The detector consists of a 4 μm thick p-doped 10ML InAs/10ML GaSb SL absorber with a 50% cut-off wavelength of 5 μm at 80 K and zero bias. The n-type doped InAs/AlSb SL barrier in the structure was included to reduce the GR dark current. By fitting the experimentally measured EQE data to the theoretically calculated QE based on the solution of the drift-diffusion equation, the p-type absorber was found the have Ln = 10 ± 0.5 μm at 80K, and Ln = 12 ± 0.5 μm at 120K and 150K. We performed the absorption coefficient measurement at different temperatures of interest. Also, we estimated the reduced background concentration and the built-in potential by utilizing a capacitance-voltage measurement technique. We used time-resolved-photoluminescence (TRPL) to determine the lifetime at 80K. With the result of the model and the lifetime measurement, we calculated the diffusion coefficient and the mobility in the T2SL detector at various temperatures. Also, we studied the behavior of different dark current mechanisms by fitting the experimentally measured and simulated dark current density under different operating temperatures and biases.
Zahra Taghipour, Alireza Kazemi, Stephen Myers, Priyalal Wijewarnasuriya, Sen Mathews, Elizabeth H. Steenbergen, Christian Morath, Vincent M. Cowan, Gamini Ariyawansa, John Scheihing, and Sanjay Krishna, "Extraction of minority carrier diffusion length of MWIR Type-II superlattice nBp detector," Proc. SPIE 10404, Infrared Sensors, Devices, and Applications VII, 1040406 (Presented at SPIE Optical Engineering + Applications: August 09, 2017; Published: 30 August 2017); https://doi.org/10.1117/12.2274591.
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