The goal of this advanced component technology (act) proposal is to develop next-generation detectors using emergent antimonide superlattice technology for space lidar instruments in support of esto s…

The goal of this advanced component technology (act) proposal is to develop next-generation detectors using emergent antimonide superlattice technology for space lidar instruments in support of esto s mission of measuring natural earth phenomenon crossing most of the focus areas outlined in the 2017 decadal survey. Primary applications will include swath mapping and vegetation profiles but the detectors can be used for many other science applications including atmospheric backscatter and absorption measurements. There is a need for new lidar detectors with high quantum efficiency sensitivity and dynamic range. Recently hgcdte avalanche photodiode (APD) arrays have provided a major breakthrough in space and airborne lidar detectors with high quantum efficiency low dark current high multiplication gain and low excess noise factors. However these detectors need to be cooled to low temperatures (~100K) because the dark current increases at higher temperatures and becomes unstable. Moreover production of detectors based on II-VI alloys is hampered by low yield limited fabrication of large format arrays and high cost. A team of scientists and engineers from academia (the ohio state university/university of illinois chicago) small business (SK infrared LLC) and a NASA center (goddard space flight center) propose to develop novel band structure engineered type-II superlattice antimonide (beta) apds using mature III-v semiconductor materials on INP substrates. The proposed approach will remove the need for cryogenic cooling and provide a manufacturable path using III-v compound semiconductor foundries. The project will combine robust theoretical and experimental research and development to demonstrate small format (4X4) linear mode APD arrays with the goal of operating at t > 240 k with a 50% cut-off wavelength > 2.05 micron. This cut-off wavelength will support a variety of lidar systems based on fiber lasers operating at 1.03 1.55 and 2 micron. The target specifications for the APD will be a high multiplication gain low excess noise factor and low dark current density at the operating bias. The key innovation is to separately engineer the electron and hole impact ionization coefficients using strained layer superlattices and digital alloys of iiiv quaternary semiconductors on INP substrates. The final deliverable will be a functioning small format array that is demonstrated at high operating temperatures and tested in a laboratory environment (TRL 4). The technical plan focuses on rapid iterations of modeling material growth device fabrication and characterization of multiplier as well as separate absorption and charge multiplication candidates to demonstrate the desired performance goals. This technology can be rapidly transitioned to large format focal plane arrays beyond the scope of this act project to support the development of new lidar instruments with capabilities that greatly exceed the current state of the art. Therefore the proposed technology will be disruptive because IT enables operation close to room temperature which will lead to a reduction in the size weight power consumption risks cost and development time of future earth remote sensing systems.