Investigations of quantum efficiency in type-II InAs/GaSb very long wavelength infrared superlattice detectors. (April 2016)

• Record Type: Journal Article
• Authors: Li, Xiaochao; Jiang, Dongwei; Zhang, Yong; Liu, Gang; Wang, Dongbo; Yu, Qingjiang; Zhao, Liancheng
• Is Part Of: Superlattices and microstructures. Volume 92(2016)
• Page Start: 330
• Page End: 336
• Publication Date: 2016-04
• Subjects: InAs/GaSb superlattices -- Photodetector -- Quantum efficiency -- Hole diffusion length; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2016.02.041
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: In this paper, we have investigated the quantum efficiency ( QE ) of InAs/GaSb T2SL very long wavelength Infrared (VLWIR) photodetectors with 50% cutoff of 12.7 μm. Due to the small depletion width and similar absorption coefficient in the T2SL material system, the minority-carrier diffusion length was determined as the key element to improve the QE of VLWIR T2SL photodetectors. The minority-carrier diffusion length was estimated by a comparison of the experimental data with the Hovel model. Our result suggest that the short hole diffusion length ( L h ∼ 520 nm) and the large its ratio to the width of this region ( x n /L h ) are considered against the photo-excited carrier collection in the T2SL photodetectors. In addition, the influence of surface recombination velocity ( S h ) on the QE of the T2SL photodetectors is also studied. The change of QE with S h is not so significant due to the relatively low absorption coefficient and short hole diffusion length in our photodetector. Graphical abstract: The PIN junction of the InAs/GaSb superlattice VLWIR photodiode and the QE of the photodiode obtained experimentally and calculated by an analytical model. Highlights: The quantum efficiency of InAs/GaSb T2SL VLWIR photodetectors with 50% cutoff of 12.7 μm was investigated. The minority-carrier diffusion length was determined as the key element to improve the QE of VLWIR T2SL photodetectors. The short hole diffusion length and the large ratio to the width are against the photo-excited carrier collection.