Carrier generation and transport in InGaAs/GaAs multiple quantum well solar cells

Carrier generation and transport properties of GaAs p-i-n structure solar cells incorporating an In_xGa_1-xAs/GaAs multiple quantum well (MQW) are reported. In this type of solar cell, carrier recombination in the MQW should be suppressed to a level far below photogeneration, hence we studied the carrier transport by measuring the photocurrent of MQW solar cells with different potential depths, at various temperatures, under various applied voltages. Photocurrents for samples with 0⩽x⩽0.15 at room temperature showed that the ratio of the number of photogenerated carriers contributing to the photocurrent to the number of absorbed photons, expressed as quantum efficiency, was almost unity. The experimental results are well expressed with the theoretical efficiency of the carrier transport over the MQW in which recombination and escape of carriers are characterized by lifetimes depending on the potential depth of the well