September 1, 2017
MicroLink Devices is pleased to announce that it has been awarded the following NASA SBIR 2017 Phase I programs.
1) Title: Flexible High-Efficiency Solar Panels for SmallSats and CubeSats
MicroLink will develop and test, a new type of photovoltaic module that will be suitable for use in SmallSat and CubeSat platforms requiring maximum power in a highly stowable format. Utilizing MicroLink's high-efficiency, lightweight, and flexible epitaxial lift-off (ELO) solar cell process, an advanced flexible solar array suitable for space will be assembled that will demonstrate a pathway for producing significantly larger arrays capable of outputting powers in excess of 100 W. The typical areal weight of conventional Ge-based space cells with a 5 mil thick rigid coverglass exceeds 1,000 g/m2. MicroLink's proposed flexible photovoltaic module with ultra-thin ELO solar cells and flexible coverglass material will not only be flexible and comparable in efficiency to Ge-based cells but also have an areal mass of less than 400 g/m2. This represents greater than a 60% reduction in weight which is of particular importance for SmallSat and CubeSat applications.
The high-efficiency, flexible, and highly stowable solar panel technology to be developed in this Phase I program is ideally suited for building low-cost, high efficiency and lightweight power sources for potential NASA programs including solar electric propulsion and small satellites. Further, the technology developed under this program will lead to more efficient and more power dense space solar arrays, which will enable applications that are not possible today. The ELO process provides a unique technology platform that cannot be matched by any other technology at the present time.
2) Title: Radiation Tolerant 35% Efficient Phosphide-Based 4-Junction Solar Cell with Epitaxial Lift-Off
MicroLink Devices will develop a phosphide-based ELO-IMM four-junction (4J) solar cell that will enhance the performance and capabilities of solar photovoltaic arrays for a variety of future NASA missions. Relative to state-of-the-art incumbent (Al)GaInP/GaInAs/Ge 3J space solar cells, the proposed phosphide-based 4J solar cell has superior radiation tolerance, higher beginning-of-life (BOL) and end-of-life (EOL) efficiencies, lower areal mass density, higher specific power, and lower cost. The improved radiation tolerance is enabled by eliminating arsenide-based subcells in favor of only phosphide-based subcells. A reduction in the mass of the solar cell relative to incumbent technology is enabled by removal of the thick GaAs substrate. Cost savings compared to incumbent technology are enabled by the recovery and reuse of the substrate via the ELO process. The superior radiation tolerance can also relax the requirements for radiation shielding, enabling further reductions in array mass and stowed volume. The proposed 4J solar cell structure includes 2.10 eV AlGaInP, 1.70 eV GaInP, 1.35 eV InP, and 1.05 eV GaInPAs subcells. The AM0 1-Sun BOL efficiency of this structure is projected to be 35% at 300K. The remaining power fraction after exposure to 1 MeV electrons at a fluence level of 1E15 cm-3 is projected to be 92%.
3) Title: 3D Nano-Epitaxial Lateral Overgrowth (nano-ELOG) of Large Area, Highly Efficient, and Flexible Multijunction Solar Cells for Space Applications
By Epitaxial Lateral Overgrowth (ELOG) and Selective Area Growth (SAG) in nanometer scales, MicroLink Devices will develop the next generation of multijunction solar cells for space applications. This is the first attempt to use advanced surface nano-engineering technologies to control the formation, propagation and annihilation mechanism of extended defects including dislocations in multijunction solar cells. There is a significant gap between the theoretically calculated efficiency of multijunction solar cells and the experimental results. That efficiency gap increases with the addition of each junctions/subcells. Misfit dislocations created due to high lattice mismatch between subcells play a major role in hampering the efficiency and reliability of such devices. A successful implementation of nano-ELOG in solar cells will results in 3J solar cells with significantly reduced dislocation density, resulting in an improved Voc and Isc and conversation efficiencies of the cells. Therefore, MicroLink will utilize this method to grow devices with increased number of junctions to reach practical efficiencies close to 40% (6J) from the current 30% (in commercially available 3J cells) in AM0 and 1-sun conditions.
This technology will enable the manufacture of low-cost, high-efficiency, highly reliable and lightweight solar cell arrays for use in solar-powered spacecraft. The resulting lightweight flexible solar cell arrays with improved record-efficiencies will be an attractive replacement for the existing stiff, heavy carbon fiber panel-based arrays. For NASA, this will be an enabling technology for solar electric propulsion or any mission that requires electrical power. Inner Space and outer Space missions including NASA's Mars program can benefit from the developed technology.
About MicroLink Devices:
MicroLink Devices is an American owned company located in Niles, IL. Dr. Noren Pan cofounded MicroLink Devices in 2000. MicroLink has specialized in the growth of epitaxial structures that are used to make the high performance HBTs and power amplifiers that are essential to the high-speed communications industry. MicroLink is an ISO 9001 certified semiconductor manufacturer. Over the last eight years, MicroLink has been a prime federal contractor on projects to develop solar cells, detectors, lasers, and high-speed transistors. In recent years, MicroLink has ramped up the production of its ELO-based solar cells and sheets for use in mobile power generation applications.