Investigation of InAsSb infrared photodetectors for near room temperature operation

Long-wavelength infrared (LWIR) photodetectors operating at near room temperature are highly desirable for a number of applications. Narrow bandgap semiconductors have been long researched for applications in the infrared photodetectors and much progress has been made on the II-VI compounds. Recent rapid development in epitaxial thin film growth techniques made it possible to explore the more promising III-V material systems. In this article, we report the recent results on the near room temperature operation of III-V InAs_1-xSb_x photodetectors. InAs_1-xSb_x detector structures were grown on GaAs substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The structural, optical, and electrical properties of this material were investigated in detail. Device modeling has been performed prior to the growth of detector structures. Photoconductive detectors with x = 0.77 exhibited photoresponse up to 14 μm at 300 K. Corresponding effective lifetime of ∼ 0.14 ns and Johnson noise limited detectivity at 10.6 μm of 3.3 × 10⁷ cmHz^1/2/W have been obtained at 300 K. Because of many advantages of the photovoltaic devices, photovoltaic detectors have been also fabricated. A room-temperature photoresponse of up to 13 μm has been observed at 300 K with a x ∼ 0.85 sample and R₀A product of ∼ 10^-5 Ωcm². These results showed the feasibility of using InAs_1-xSb_x for uncooled photodetector applications as an alternative to Hg_1-xCd_xTe.