Abstract: Embodiments described herein relate to a dual-band photodetector. The dual-band photodetector includes a barrier layer (10) disposed between two infrared absorption layers (8, 12) wherein the barrier layer (10) is lattice matched to at least one of the infrared absorption layers (8, 12). Furthermore, one infrared absorption layer includes dilute nitride to adjust the band gap to a desired cut-off wavelength while maintaining valence-band alignment with the barrier layer. Embodiments also relate to a system and processes for producing the photodetector fabricated from semiconductor materials.

Abstract: Embodiments relate to photodetectors comprising: a substrate and a bulk-alloy infrared (IR) photo absorption layer disposed on the substrate to absorb photons in an infrared wavelength and having a graded section and an ungraded section. The photodetector comprises a unipolar barrier layer disposed on the bulk-alloy photo absorption layer. The graded section includes a graded alloy composition such that its energy bandgap is largest near the substrate and smallest near the unipolar barrier layer. The embodiments also relate to methods fabricating the photodetectors.