High-Speed Radiation Tolerant Avalanche Photodiodes Based on InGaN for Space Altimeter Systems

High-performance, radiation-tolerant detectors are required for the time-of-flight laser based rangefinders. Avalanche photodiodes (APDs) are conventionally chosen as detectors for standard laser rangefinder systems. However, the performance of currently used APDs degrades significantly after exposure to high levels of radiation. Integrated Micro Sensors Inc (IMS, Houston, TX)) proposes novel intrinsically radiation-tolerant III nitrides based high-speed APDs superior for use in space-based laser-altimeter systems. The Indium Gallium Nitride (InGaN) alloy has the potential of forming photovoltaic devices covering a range of 0.7 eV (InN) to 3.4 eV (GaN). This energy range allows for providing a perfect match to the 1.06 um wavelength (~1.17 eV) of the lasers used in the time-of-flight range finders. The III-Nitrides exhibit inherent chemical and thermal ruggedness, which makes them suitable for several space and military applications. It has recently been determined that these Nitride materials can offer exceptional radiation tolerance that is well beyond what can be achieved with conventional materials that are currently flown into space. The InGaN APDs to be developed in this project will be targeted for operating conditions up to 250 oC, and up to 2 MeV proton irradiation, which are substantially higher than those for the standard currently used materials, such as Si or GaAs. IMS envisions that devices developed in this project would be especially beneficial to Europa Jupiter System Mission (EJSM) that requires high performance sensors and detectors that can operate with low noise under the severe radiation environment.The ultimate goal of this project is to develop high-speed, radiation-tolerant visible-blind APDs responding to laser beams of 1.06 um wavelength for rangefinder applications.