Investigation of InAs/GaAs 1−x Sb x quantum dots for applications in intermediate band solar cells

Self-assembled InAs quantum dots (QD) in a GaAs1−xSbx matrix are studied using photoluminescence. Increasing the Sb composition in the GaAs1−xSbx matrix reduces the effective band gap while lowering the valence band offset, resulting in transition from a type-I to type-II band alignment for Sb compositions above 14%. The optimized quantum dots are incorporated in an InAs/GaAs1−xSbx based p–i–n solar cell with a degenerate valence band and therefore optimum intermediate band structure. Temperature dependent external quantum efficiency measurements show an enhancement in the QDs region with increasing temperature.