Carriers transport properties in GaInP solar cells grown by molecular beam epitaxy

The transport properties of carriers in GaInP solar cells grown by molecular beam epitaxy are investigated by temperature-dependent current–voltage (I–V) measurements. In contrast to GaInP/AlGaInP heterostructure, a long PL decay time is observed in GaInP/AlInP, which is ascribed to a lower interface recombination due to an improved carriers׳ confinement in the case of the high-energy barrier. However, the series resistance induced by the high potential barrier at GaInP/AlInP interface due to a big valence band offset prevents the improvement of solar cell׳s performance. An S-shape like I–V characteristic observed at low temperatures indicates that the transport of major carriers is limited by the barrier. A calculation based on the combination of a normal photovoltaic device with a barrier-affected thermal carriers transport explicitly explains this abnormal I–V characteristic. Our study demonstrates the critical role of the barrier-induced series resistance in the determination of solar cell׳s performance.