InAsSb photodiodes grown on GaAs substrates for long-wavelength-infrared gas-sensing applications

Abstract

We investigated highly mismatched InAsSb photodiodes (PDs) grown on GaAs substrates working in the long-wavelength-infrared range (8-12 µm). Because of their low absorption coefficient levels and high Auger recombination rates, InAsSb PDs suffer from several difficulties, including low responsivity and low resistance levels at room temperature. Additionally, the large lattice mismatch between the active layer and substrate material introduces a high density of dislocations and thus degrades performance. In the work described in this report, we realized high-performance InAs 0.13 Sb 0.87 PDs by reducing the density of dislocations as a result of applying a dislocation filter structure, as well as by optimizing interference within the active layer. The resulting device (cut-off wavelength of about 11 µm) showed, at room temperature, a resistance R 0 of 90 kΩ and responsivity R i of 0.47 mA W −1 at a wavelength of 9.5 µm, leading to a high detectivity D * of 1.2 × 10 8 cm Hz 1/2 W −1 , which is suitable for detecting alcohol.

Monolithic integration of a 10 μm cut-off wavelength InAs/GaSb type-II superlattice diode on GaAs platform

“…This is largely due to its coincidence with both the long-wavelength infrared (LWIR) spectral window and the peak emission of blackbody objects at room temperature. Furthermore, LWIR detectors, lasers, and LEDs are required for applications such as ethanol 42 and freon 43 sensing. However, there are also considerable challenges associated with this wavelength due to the small (~ 0.12 eV) bandgap leading to high thermal currents.…”