Short circuit current enhancement of GaAs solar cells using strain compensated InAs quantum dots

Abstract

Tensile strain compensation (SC) layers were introduced into GaAs p-i-n solar cells grown with a five-stack of InAs quantum dots (QDs) within the i-region. The effects of strain within stacked layers of InAs quantum dots (QDs) were investigated using high resolution x-ray diffraction (HRXRD). Analysis of the HRXRD data shows that the average lattice strain is minimized for the optimal SC thickness. One sun air mass zero illuminated current-voltage curves show that SC results in improved conversion efficiency and reduced dark current when compared to uncompensated devices. The strain compensated 5-layer QD solar cell shows a 0.9 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> increase in short circuit current compared to a baseline GaAs cell. Quantum efficiency measurements show this additional current results from photo-generated carriers within the quantum confined material.