Growth optimization and process development of indium gallium nitride/gallium nitride solar cells

Abstract

Indium gallium nitride solar cells have shown promise but the overall performance is limited by several factors. First it is difficult to grow thick, high quality, high indium content absorber layers. We have shown that using a semibulk approach we can achieve a high short circuit current and record peak EQE for III-nitride based solar cells. Second, we used p-GaN grown at low temperatures in order to maintain the temperature sensitive InGaN absorber. This results in a morphology rich in v-pits. We show that these v-pits increase the short circuit current but at the cost of a high leakage current reducing the fill factor and Voc. We demonstrate a method of passivating the v-pits that preserves the short circuit current and reduces the leakage current. Lastly optimizations were made and are discussed on the device design and fabrication.