Growth of phosphide-based type-II stacked quantum dots for III–V/Si photovoltaic applications

Abstract

The necessity for improved renewable energy sources has increased in recent years, particularly solar cells have been continuously improving. This study proposes a type-II quantum dot (QD) structure using InP and GaP-based III–V–N alloys to enhance electron/hole spatial separation for photovoltaic applications. With appropriate size and thickness, InP QD/GaAsPN enables type-II band alignment. Additionally, it has a tunable bandgap of approximately 1.7 eV with strain compensation conditions on a Si substrate, which enables dislocation-free III–V/Si tandem cells. Self-assembled nanostructures of InP were fabricated on GaP, and two types of islands were observed. Growth parameters were investigated to ensure better control over the morphology of islands. Subsequently, the optimized parameters were employed for fabricating a 30-period good quality InP/GaP stacked QD structure without any strain compensation layers. These results may help in designing more efficient GaP-based III–V–N solar cells on Si substrates.