Influence of As/group-III flux ratio on defects formation and photovoltaic performance of GaInNAs solar cells

The correlation between the As to group III flux ratio and photovoltaic performance of GaIn0.1N0.03As solar cells fabricated by molecular beam epitaxy is systematically investigated. The results show that flux ratio has a remarkable influence on the formation of defect traps. Furthermore, the formation of defects at different flux ratios is correlating with the variation of the background doping level and the photovoltaic performance. In particular, this study reveals a linear dependency between current generation, dark saturation current, defect densities, photoluminescence peak intensity and the flux ratio. A significant increase in solar cell performance, exhibiting maximum external quantum efficiency of 90%, is obtained when As/group-III ratio is decreased close to the stoichiometric limit. For optimized growth condition, the 1eV GaIn0.1N0.03As solar cell exhibits a short circuit current density as high as 17.9mA/cm2 calculated from the external quantum efficiency data (AM0 conditions) with 870nm high-pass filter. This value reflects the potential of the GaInNAs cell for current matching and power generation in high efficiency solar cells incorporating three- or four- junctions. [Display omitted] •V/III BEP ratio is found to influence remarkably on GaInNAs solar cell performance.•Linear dependency between V/III BEP ratio and many materials parameters is observed.•The improved current and voltage generation is linked to reduction of defects.•Optimized 1eV band gap GaInNAs cell fulfills the current matching requirements.