Dilute bismuth incorporated InGaBiAs photodetectors for extended short-wave infrared detection

Abstract

Dilute bismuth (Bi) incorporated InGaBiAs is a promising material for an extended range of short-wave infrared (e-SWIR, 1.7–2.5 μm wavelength) detection. The InGaBiAs is a highly mismatched semiconductor alloy, where small concentrations of Bi incorporation alter the electronic band structure due to the valence band anti-crossing interaction between Bi states and host InGaAs material, resulting in a decrease in the bandgap energy. In this work, photodetectors based on InGaBiAs alloys lattice matched to InP demonstrate an extension of the cutoff wavelength beyond 2 μm. Dark current density, minority carrier lifetime, and responsivity strongly depend on group-V arsenic overpressure during epitaxial growth. Photodetectors grown under high arsenic flux pressure show low dark current values at room temperature (1.0 × 10−3 A/cm2 at 100 mV reverse bias), an order of magnitude lower than stoichiometric and low As flux grown devices, and correspondingly higher lifetime and responsivity. Two distinct activation energies were identified for each growth condition based on temperature-dependent dark current analysis, with trap-assisted generation-recombination in the depletion region and shallow defect recombination as the dark current-limiting factors in all devices.