InGaP/GaAs tandem solar cells fabricated using solid-source molecular beam epitaxy

We report high-quality InGaP solar cells and their application to InGaP/GaAs tandem solar cells fabricated using solid-source molecular beam epitaxy (MBE). The short-circuit current density of InGaP solar cells increases as the absorption layer thickness increases. The highest efficiency of 12.8% with an open circuit voltage ( V oc ) of 1.32 V was obtained without anti-reflection coating. The performance of InGaP/GaAs tandem solar cells is considerably changed by changing the carrier concentration in a tunnel junction between the top InGaP and bottom GaAs cells. A high efficiency of 21.1% was obtained with a high V oc of 2.3 V, which indicates that high-performance InGaP/GaAs tandem solar cells can be fabricated using solid-source MBE.