High Efficiency InGaN Multijunction Solar Cells

This Phase I STTR program will demonstrate the feasibility of fabricating inherently radiation hard, high efficiency solar cells based on In(1-x)Ga(x)N photovoltaic devices using MOCVD. Recent results show that InN has a much narrower bandgap than previously believed: 0.7 eV, compared to earlier estimates of 2 eV. This discovery opens the door to fabrication of photovoltaic devices responsive from the near infrared through UV ranges. Thus, unprecedented efficiencies should be possible. In addition, GaN-based solar cells have potentially greater radiation resistance and ability to operate under temperature extremes than those currently available. In this program, Dr. William Schaff of Cornell University (a pioneer in InN and InGaN technology) will lead material optimization efforts and Structured Materials Industries, Inc. (SMI) will focus on demonstrating high efficient nitride MOCVD, to carry GaN-based solar cells from laboratory to production. The team will deposit In(1-x)Ga(x)N films of varied composition, and demonstrate p- and n-doping and junction formation, and develop cell designs, to demonstrate the feasibility of radiation hard, high efficiency In(1-x)Ga(x)N solar cells. Fabrication and demonstration of prototype devices and process scale-up will take place in Phase II. Successful completion of this program will enable a new class of radiation-hardened, robust, efficient, economical solar cells for space and terrestrial applications.