Type-II band alignment, which spacialy separate electrons from hole is advantageous for solar cell and detector applications. We focused on the quantum dot (QD) solar cell structures based on type-II InAs/GaAs.
We show, that InAs QD capped with GaAsSb strain reducing layers not only separates electrons and holes when they are generated, but also causes that electrons and holes have non-intersecting trajectories which prevents carrier recombination and improves the efficiency of solar cell structures. NextNano band structure calculations of different types of structures support our experimental results.
Dependence of normalized photocurrent on incident light wavelength for samples
with 5 QD layers covered by a type-II GaAsSb SRL with different composition gradations.
Simulation of structure parameters by NextNano software.