Alpha radiation effects on n-i-p quantum dot epitaxial lift-off solar cells

Abstract

Embedded nanostructures such as quantum dots (QDs) have been studied for many applications including enhanced mini-band absorption in intermediate-band solar cells and current matching in multi junction cells. Furthermore, solar cells with QDs have shown a radiation hardness and temperature tolerance that has been improved by adding nanostructures. InAs/GaAs QD cells were grown by MOVPE, fabricated and processed by epitaxial lift off, creating thin and flexible devices that exhibit enhanced sub-GaAs bandgap current collection. Due to the thinning of these devices, the sub-GaAs bandgap eternal quantum efficiency curves are more pronounced than those for a thicker cell, indicating the presence of a cavity mode effect. Champion devices incorporating QDs have short circuit currents exceeding those of baseline samples with no QDs by an absolute value of 0.12 mA/cm2 under 1-sun AM0 illumination. In addition to optical, materials, and electrical characterization, devices were exposed to alpha radiation to gauge the effects of a harmful environment on cell performance. In this area QD cells also outperformed baseline devices, with a relative end of life remaining maximum power factor increase of 10%.