Strain-compensated InAs/GaNAs quantum dots for use in high-efficiency solar cells

We have investigated GaAs-based p-i-n quantum dot solar cells (QDSCs) with 10 up to 20 stacked layers of self-assembled InAs quantum dots (QDs) grown by atomic hydrogen-assisted molecular beam epitaxy. The net average lattice strain was minimized by using the strain-compensation technique, in which GaNAs dilute nitrides were used as spacer layers. The filtered short-circuit current density beyond GaAs bandedge was 2.47 mA/cm2 for strain-compensated QDSC with 20 stacks of InAs QD layers, which was four times higher than that for strained QDSC with identical cell structure.