Multistep InAs/InAsSb staircase nBn long-wavelength infrared detectors with enhanced charge carrier transport

• Published in: Infrared physics & technology Vol. 134; p. 104856
• Main Authors: Cui, Xinyue, Yuan, Qi, Guo, Daqian, Li, Chuang, Shen, Kai, Wu, Jiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2023
• Subjects: Carrier transport; InAs/InAsSb; Long-wavelength infrared detector; Multistep staircase; Multistep staircase; Long-wavelength infrared detector; InAs/InAsSb; Carrier transport
• ISSN: 1350-4495; 1879-0275
• DOI: 10.1016/j.infrared.2023.104856

Gallium-free Type-II superlattices (T2SLs) have emerged as promising candidates for high-performance long-wavelength infrared (LWIR) detectors at a high operating temperature. However, InAs/InAsSb barrier detectors suffer from the limited absorption efficiency, resulting in a trade-off between quantum efficiency (QE) and dark current. Here, a nBn LWIR detector based on multistep strain-balanced InAs/InAs0.5Sb0.5 superlattice staircase configuration is proposed. With this configuration, charge carrier transport and collection can be efficiently improved via the multistep staircase valance band, leading to an increased QE from 19.3% to 20.8% at a bias of −0.20 V. As a result, the device with multistep staircase configuration exhibits an improved performance, including a low dark current density of 4.13 × 10−5 A/cm2, high responsivity of 1.23 A/W and peak detectivity reaching 3.10 × 1011 cm·Hz1/2/W. By optimizing absorbing length of the multistep staircase absorber, the peak QE can be further boosted from 20.8% to 28.4% while maintaining a low dark current level, providing an alternative strategy to improve LWIR T2SL device performance.