Optimization of GaAs Solar Cell Performance and Growth Efficiency at MOVPE Growth Rates of 100 μm/h

Abstract

III–V devices outperform all other solar cells in terms of efficiency. However, the manufacturing of these cells is expensive and prevents their use in a number of applications, which would benefit from the high efficiency. A major contribution to the cost is the metal–organic vapor phase epitaxy process for the III–V compounds. Increasing growth rates and, hence, machine throughput, as well as the growth efficiency, are important steps toward reducing the cost of III–V solar cells. We demonstrate the growth of GaAs solar cells at extremely high growth rates of 100 μm/h and achieve a V OC of 1.028 V, a base diffusion length of 6.5 μm, and an efficiency of 23.6% under AM1.5g conditions. Furthermore, we show reactor adjustments leading to growth rates up to 140 μm/h and reach conditions where more than half of the Ga from the precursor is incorporated into the solar cell layers. The results are encouraging and demonstrate a pathway toward lower cost III–V solar cell manufacturing.