Fabrication of InAs 2D submonolayer nanostructure-based solar cells with InGaAs/GaAsSb double-well structure

In this study, multi-stack InAs submonolayer (SML) nanostructures (NS) were sandwiched in an InGaAs/GaAsSb double-well (DWELL) structure to improve the material quality of InAs 2D SML NSs and the device characteristics of nanostructure-based solar cells (NSSCs). The photoluminescence intensity of the InAs 2D SML nanostructures with the DWELL structure was greater than that of conventional InAs/GaAs 2D SML NSs because of reduced In–Ga intermixing and enhanced carrier confinement (carrier activation energy was increased from 21 to 66 meV). Transmission electron microscopy results did not reveal any obvious epitaxial defect or crystal dislocation in the DWELL structure, indicating that high crystal quality 2D SML NSs can be achieved by using the InGaAs/GaAsSb DWELL heterostructure. Compared with the NSSCs with the reference InAs/GaAs 2D SML NSs, the 2D SML nanostructure NSSCs with the DWELL structure exhibit a greater external quantum efficiency in the range of 940–990 nm. The NSSCs with the DWELL structure also exhibited an increased short-circuit current density of 18 mA/cm² with an enhanced open-circuit voltage of 0.73 V and a conversion efficiency of 6.80 %, highlighting the advantages InAs 2D SML NSs with the DWELL structure.