Monolithically Integrated InAsSb-Based nBnBn Heterostructure on GaAs for Infrared Detection

The high-operating temperature infrared photodetectors with multicolor function that are capable of monolithic integration are of increasing importance in developing the next generation of the mid-IR image sensors. Applications of these sensors include defense, medical diagnosis, environmental, and astronomical observations. We have investigated a novel InAsSb-based nBnBn heterostructure that combines a state-of-the-art InAsSb nBn detector with an InAsSb/GaSb heterojunction detector. At room temperature, the reduction in the dark current density of more than an order of magnitude was achieved compared to the previously investigated InAsSb/GaSb heterojunction detectors. Electrical characterization from cryogenic temperatures to room temperature confirmed that the nBnBn device was diffusion limited for the temperatures above 150 K. Optical measurements demonstrated that the nBnBn detector was sensitive in both the SWIR and MWIR wavelength range at room temperature. The specific detectivity (D*) of the competed nBnBn devices was calculated to be 8.6 × 10
⁸
cm · Hz
^1/2
W
^-1
at 300 K and approximately 1.0 × 10
¹⁰
cm·Hz
^1/2
W
^-1
when cooled down to 200 K (with 0.3 V reverse bias and 1550-nm illumination). In addition, all the photodetector layers were grown monolithically on GaAs active layers using the interfacial misfit array growth mode. Our results, therefore, pave the way for the development of new active pixel designs for the monolithically integrated mid-IR imaging arrays.