AFRL Nanotechnology Initiative: Hybrid Nanomaterials in Photonic Crystal Cavities for Multi-Spectral Infrared Detector Arrays

Abstract

Abstract : The goal of this project was to demonstrate the feasibility of a multi-spectral infrared (IR) photodetector using hybrid nanomaterials in photonic crystal (PC) cavities for enhanced absorption at selected wavelengths. The simultaneous sensing of multiple IR wavelengths, particularly in the near-IR and mid-IR is important because it enables intelligent surveillance, target recognition, and chem-bio detection. This project investigated InAs/GaAs epitaxial quanttun dots (EQDs) and colloidal quantum dots (CQDs). By incorporating these nanomaterials in one-dimensional (1D) and two-dimensional (2D) PC cavities, the possibility of multi-spectral configurability and enhanced absorption was explored. It was demonstrated that integrating EQDs with 2D PC cavities (etched air holes) is challenging due to difficulty in matching photonic bandgap defect modes with InAs/GaAs EQD absorption peaks. Nonetheless, enhanced absorption was demonstrated in a specific defect mode at 8 um at low temperatures. In contrast, it was straightforward to enhance absorption at specific wavelengths at room temperature by integrating CQDs with 1D PC cavities (polymer distributed Bragg reflectors). An enabling technology was matrix-assisted pulsed laser evaporation.