Effect of indium fluctuation on the photovoltaic characteristics of InGaN/GaN multiple quantum well solar cells

Severe In fluctuation was observed in In(0.3)Ga(0.7)N/GaN multiple quantum well solar cells using scanning transmission electron microscopy and energy dispersive x-ray spectroscopy. The high In content and fluctuation lead to low fill factor (FF) of 30% and energy conversion efficiency (eta) of 0.48% under the illumination of AM 1.5G. As the temperature was increased from 250 to 300 K, FF and eta were substantially enhanced. This strong temperature-dependent enhancement is attributed to the additional contribution to the photocurrents by the thermally activated carriers, which are originally trapped in the shallow quantum wells resulting from the inhomogeneous In distribution.