The proposed work is in direct response to a NASA solicitation seeking high-bandwidth (up to 6 Ghz) single-element and/or array detectors for coherent wind measurements in the 1.5- to 2.5- micrometer wavelength range. The design, development, and production of a new family of uncooled Separate-Absorption-Multiplication Avalanche Photodiodes (SAM-APDs) and made in III-V antimonide alloys with high-quantum efficiencies in the 1.5- to 2.5-micron wavelength band will be undertaken. These detectors will be optimized for use as detectors in eye-safe LIDAR and other systems being developed for wind shear measurements applications. The proposed innovations are based on improvements in materials and fabrication technology (e.g., optimized epitaxial growth for target bandgap alloy compositions, rare-earth doping, tailored impurity diffusion profiles, improved surface and edge passivation, and defect reduction), and on novel design features (optimized device structure, planarized contacts, resonant cavities and buried mirrors), all of which will improve various device performance metrics including quantum efficiency, spectral sensitivity, speed, signal-to-noise ratios, and further, will extend the response of today?s state-of-the-art devices to wavelengths of 2.5 microns or longer. POTENTIAL COMMERCIAL APPLICATIONS In addition to detectors for LIDAR wind turbulence measurements, the proposed devices will find important applications in molecular spectroscopy, flame detectors, remote sensing, laser satellite communications, and low-loss fluoride fiber receivers.
