Improved efficiency of InAs/GaAs quantum dots solar cells by Si-doping

Abstract

This paper reports on significantly improved efficiency of InAs/GaAs quantum dot (QD) solar cells by directly doping Si into InAs QDs during the QD growth. The devices which contain five stacked QDs in their i-regions were grown using molecular beam epitaxy. It is shown that using appropriate Si-doing, the open-circuit voltage of the device can be increased to 0.84V. This is dramatically higher than the value of 0.67V obtained in undoped device using the same structure. Moreover, the efficiency of corresponding device is improved from 11.3% to 17.0%. This improvement in efficiency is attributed to greatly reduced energy loss in the devices that results from the reduction of the defect density in the stacked InAs/GaAs QD layers due to the doping.