A Low-Power Optoelectronic Characterizer for CubeSat: LOCC and III-V Nitride Based LEDs

Abstract

A Low-Powered Optoelectronic Characterizer for CubeSat: LOCC and III-V Nitride Based LEDs Matthew J. Pachol III-V semiconductor materials exhibit robustness and natural hardness when exposed to ionizing radiation and temperature swings. With these characteristics in mind, III-V Nitride Light Emitting Diodes (LEDs) are ideal devices for space-based applications and missions. The effects of ionizing radiation on optoelectronic devices comprised of III-V materials have been studied, but results have been obtained through experiments performed in terrestrial laboratories. While these laboratory tests may lend insight into device lifetimes, performance degradation, etc., they are no substitute for similar measurements and characterization performed in space. Interest in small satellite applications have grown over the past decade. These solutions range from Earth imaging to communication networks. Small satellites provide a unique opportunity to gain an understanding of the reliability and operational characteristics of III-V based materials and other semiconductor devices while exposed to the environment of space. To meet the constraints of the small satellite, a Low-powered Optoelectronic Characterizer for CubeSat (LOCC) has been developed in PC/104 form, measuring 3.6 by 3.8 inches. LOCC performs current-voltage and electroluminescent measurements of LEDs while in space. The LOCC system is designed using low-power integrated circuits that can supply over 100 mA of current to LEDs while maintaining low power of 3.2W under operation. This thesis presents the design, implementation, and control of the LOCC system. This includes system block diagrams, printed circuit board layouts, interfacing, firmware, and software. Additionally, the resulting current-voltage measurements, required wattage, and required data storage are presented to illustrate functionality. This instrumentation enables the study of optoelectronic devices in space, allowing future research to focus on producing radiation hard light emitting devices that can operate in environments with reduced shielding against ionizing radiation while maintaining device reliability.