Control of dark currents in multi-quantum well solar cells by use of thin tunnel barriers

In order to investigate the predicted performance of solar cells, which employ multi-quantum wells (MQWs) and other types of quantum structures, it is important that one achieves a high material quality with minimum non-radiative recombination losses at the QW heterointerfaces, and a high escape rate of photocarriers out of QWs into the "collector" region via optimization of MQW structures. In this work, we have investigated on; (1) the fabrication InGaAs/GaAs-based MQW solar cells by using atomic H-assisted molecular beam epitaxy (H-MBE) technique in order for efficient defect and interface control, and (2) the effect of "tunnel barriers" introduced within a conventional-type MQW solar cell comprised of a series of square-shaped QWs. In particular, this structure is intended for reducing the dark current thereby improving the overall response of MQW solar cells.