The effect of GaAs capping layer thickness on quantum dot solar cell performance

The use of nanostructures such as quantum dots (QD) offers tremendous potential to realize high-efficiency photovoltaic (PV) cells. The optimization of the electronic structure of the layers within the QD region should lead to improved PV performance. This includes the QD layer itself, but also the surrounding barrier and/or strain balancing layers that comprise the QD active region. In this paper, the effect of the GaAs capping layer thickness (i.e. the first layer grown following QD) on the optoelectronic properties of InAs QDs was investigated. The GaAs capping layer plays a crucial role in the physical and optoelectronic properties of the QD. The GaAs capping thickness strongly modifies the InAs QD wavelength and also enhances the QD emission relative to the wetting layer (WL) emission. This behavior implies a suppression of WL emission that is thought to be a drawback to high-efficiency photovoltaic performance. In the final paper, we investigate how this WL PL-suppression affects the performance of QD-enhanced GaAs single junction solar cell performance.