Design and Performance Assessment of a Mid-Wave Infrared InAsSb-based AlSb/InAlSb Barrier Photodetector for Carbonyl Sulfide Gas Detection as an Ultra-High Sensitivity Device in Industrial Applications

This study presents the design of a back-illuminated barrier photodetector, utilizing an AlSb/InAlSb compound barrier layer. Through comprehensive theoretical analysis, the device is optimized for the sensitive detection of toxic and hazardous carbonyl sulfide gas. Carbonyl sulfide, with the absorption line in the mid-wavelength infrared window, is one of the harmful unwanted products in industries, especially gas industries. In the proposed compound barrier layer photodetector, the engineered AlSb/InAlSb compound barrier layer is designed instead of the InAlSb bulk barrier layer. It has the advantage of creating near-zero valence band offset, a significant challenge in the barrier photodetectors. Also, the designed device leads to improve the possibility of extracting minority carriers produced by an optical generation process in the absorber layer with an InAs_0.81Sb_0.19 semiconductor. The simulation results exhibit that the proposed device has a dark current density of ~ 3.90 × 10^− 9 A/cm² and ~ 1.87 × 10^− 5 A/cm² at 150 K and 200 K, respectively, under a bias voltage of -0.2 V, and its behavior is diffusion limited dark current. Therefore, it can be observed that other components of the generation-recombination and tunneling process play a very small role in creating a dark current. At 150 K, the proposed device has a 50% cutoff wavelength of more than 5 μm. Based on the results, the current responsivity, specific detectivity, noise equivalent power, and the noise equivalent irradiance are obtained ~ 2.9 A/W, ~ 2.39 × 10¹² cmHz^1/2/W, ~ 2.23 × 10^− 15 WHz^1/2, and 2.47 × 10^− 6 W/cm² respectively, under − 0.2 V bias voltage and at 4.87 μm wavelength where carbonyl sulfide absorption occurs. In addition, the proposed photodetector shows high current sensitivity and linear optical dynamic range, which confirm that the designed device has a high potential compared to state-of-the-art devices for carbonyl sulfide gas detection in industries.