Thermo-tunneling design for quantum well photovoltaic converter

Abstract

A design of a quantum well region that allows faster and more efficient carrier collection in quantum well solar cells. It is shown that for a quantum well material system displaying a negligible valence band offset, the conduction band confinement energies and barrier thicknesses can be designed to favor a sequential thermionic promotion and resonant tunneling of electrons to the conduction band continuum resulting in faster carrier collection rates than for a conventional design. An evaluation of the proposed design in the context of devices incorporating GaAs/GaAsN quantum wells shows a collection of all photo-generated carriers within several to tenths of ps (10s) from deep quantum wells rather than several ns, as it is the case for conventional designs. The incorporation of the proposed design in single and multijunction solar cells is evaluated with efficiency enhancements.