Low-noise high-temperature AlInAsSb/GaSb avalanche photodiodes for 2-μm applications

Highly sensitive avalanche photodiodes that operate at near-infrared wavelengths of up to 2 mu m could prove useful for eye-safe light imaging, detection and ranging, and other applications. Sensitive photodetectors that operate at a wavelength of 2 mu m are required for applications in sensing and imaging but state-of-the-art devices are severely limited by high dark current density (J(dark)). The narrow-bandgap materials required for mid-infrared (2-5 mu m) detection are plagued by carrier recombination and band-to-band tunnelling; as a result, detectors must be operated at cryogenic temperatures. HgCdTe is currently the most commonly used materials system for these applications and has achieved J(dark) = 3 x 10(-4) A cm(-)(2) at a gain of 10 while operating at 125 K. Here, we report the details and results for avalanche photodiodes for 2-mu m detection based on a separate absorption, charge, and multiplication design in the AlxIn1-xAsySb1-y materials system. We achieve comparable J(dark) between 200-220 K and demonstrate very low excess noise (k approximate to 0.01) and gain >100 at room temperature. Such avalanche photodiodes could prove useful for receivers for eye-safe light imaging, detection and ranging.