Diffusion current characteristics of defect-limited nBn mid-wave infrared detectors

• Published in: Applied physics letters Vol. 106; no. 17
• Main Authors: Savich, G. R., Sidor, D. E., Du, X., Morath, C. P., Cowan, V. M., Wicks, G. W.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 27.04.2015
• Subjects: Applied physics; Architecture; Augers; Dark current; Defects; Diffusion layers; Diffusion length; Infrared detectors; Minority carriers; Photodiodes; Sensors; Thickness
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4919450

Mid-wave infrared, nBn detectors remain limited by diffusion current generated in the absorber region even when defect concentrations are elevated. In contrast, defect-limited conventional pn-junction based photodiodes are subject to Shockley-Read-Hall generation in the depletion region and subsequent carrier drift. Ideal nBn-architecture devices would be limited by Auger 1 generation; however, typical nBn detectors exhibit defect-dominated performance associated with Shockley-Read-Hall generation in the quasi-neutral absorbing region. Reverse saturation current density characteristics for defect-limited devices depend on the minority carrier diffusion length, absorbing layer thickness, and the dominant minority carrier generation mechanism. Unlike pn-based photodiodes, changes in nBn dark current due to elevated defect concentrations do not manifest at small biases, thus, the zero bias resistance area product, RoA, is not a useful parameter for characterizing nBn-architecture photodetector performance.