p-type doped AlAsSb/GaSb resonant tunneling diode photodetector for the mid-infrared spectral region

Mid‐infrared (MIR) resonant tunneling diode (RTD) photodetectors based on a p‐type doped AlAsSb/GaSb double‐barrier quantum well (DBQW) are proposed and investigated for their optoelectronic transport properties. At room temperature, a distinct resonant tunneling current with a region of negative differential conductance is measured. The peak‐to‐valley current ratio (PVCR) is 1.51. To provide photosensitivity within the MIR spectral region, a lattice‐matched quaternary low‐bandgap GaInAsSb absorption layer with cutoff wavelength of λ = 2.77 μm is integrated near the DBQW. Under illumination with infrared light, photogenerated minority electrons within the absorption layer can drift toward the DBQW, where they accumulate and cause a shift of the current–voltage characteristics toward smaller bias voltages, which can be exploited to measure the incident MIR light power. In a tunable diode laser absorption spectroscopy experiment, the RTD photodetector is used to identify three distinct water absorption lines in the MIR close to λ = 2.61 μm. By adjusting the absorption layer doping concentration, the RTD quantum efficiency can be increased by a factor of 10, resulting in a sensitivity of S = 2.71 A W−1, which corresponds to an estimated multiplication factor of M = 8.6.