Carrier Collection Improvement in InGaAs/GaAsN Multiple Quantum Well Solar Cell with Flat Conduction Band

Abstract

InGaAs/GaAsN multiple quantum well (MQW) with flat conduction band (FCB) was introduced to improve electron transport in a dilute N absorber. This novel structure is expected for the middle cell in a three-junction solar cell on Ge. The I-V characteristic and carrier collection efficiency (CCE) of the cells were measured under AM 1.5G illumination with 665-nm long-pass filter corresponding to the absorption of InGaP top cell. The results showed that CCE of the FCB-MQW cell is better than that of the InGaAsN bulk cell with a similar short-circuit current. By increasing the MQW period to 60, the light absorption was enhanced, and the photocurrent exceeded a current-matching value for the three-junction cell on Ge.