SPLTRAK Abstract Submission
23.5% Efficiency GaAs Solar Cells Fabricated with  Low-cost, Non-vacuum Processing
Phillip R Jahelka1, Harry A Atwater1, Aaron Ptak2, Christiane Frank-Rotsch3, Frank Kiessling3, Cora Went1, Michael Kelzenberg1
1California Institute of Technology, Pasadena, CA, United States
/2National Renewable Energy Laboratory, Golden, CO, United States
/3Leibniz-Institut für Kristallzüchtung, Berlin, Germany

We report advances in low-cost GaAs photovoltaic device processing. First, we developed an open-tube zinc diffusion technique for forming p-type layers with sheet resistance less than 100 ohms per square on GaAs and InP. Second, we use this technique along with chemical surface passivation to fabricate GaAs solar cells that , uncertified, achieve Voc  = 964 mV Voc, FF  = 82% FF, Jsc, = 29.8 mAcm-2 Jsc, and 23.5% efficiency. Third, we discovered GaAs cells with long hole diffusion length can be made byfabricated from wafers growing obtained from GaAs ingots grown in a part of the phase diagram thate minimizes the EL2 defect. Fourth, we show an in-air, precious metal-free process for making ohmic contacts to n-type GaAs.