Fast growth rate GaAs and InGaP for MOCVD grown triple junction solar cells

Abstract

Triple junction solar cells (TJSC) are the highest efficiency solar cells available today and are utilized in space and concentrator photovoltaic terrestrial applications. These cells are manufactured using metalorganic chemical vapor deposition (MOCVD) in large scale commercial reactors. Since TJSC process time is largely driven by the growth of the (In)GaAs middle cell and InGaP top cell, increasing the MOCVD growth rate can reduce the process time and increase reactor throughput. In this paper, we discuss a materials characterization comparison of (In)GaAs and InGaP grown at conventional growth rate and faster growth rates. Our results show similar material characteristics of (In)GaAs grown at ∼ 66% higher growth rate as measured by photoluminescence, x-ray, AFM surface roughness, and background doping and for InGaP grown at ∼ 57% higher growth rate for photoluminescence and sheet resistivity uniformity. These higher growth rates incorporated into a MOCVD growth process can lead to ∼ 20% reduction in process time and lower the cost of TJSC manufacture.