Experimental matrix study of leakage current in nanopillar-based devices towards high-efficiency photovoltaics

In this work, we present a detailed leakage current study on arrays of GaAs p-n junction nanopillars grown by MOCVD.[1-2] Nanopillar/nanowire-based photovoltaics are actively examined as highly efficient solar absorbers. To achieve highly-performing devices, however, a methodical understanding of the nature of leakage currents is needed.[3] Reducing leakage currents is key to improve the diode characteristic and open-circuit voltage under light, especially. This work considers a matrix of 5 × 5 different patterned geometries where pitches and diameters are changed to investigate trends in leakage currents. A 7.43% (AM1.5G) nanopillar photovoltaic cell is then experimentally demonstrated. Device characterization is carried out in terms of current-voltage (I-V) characteristics, temperature-dependent I-V, and external quantum efficiency measurements. FDTD simulations [4] are provided to substantiate the distribution of waveguided light within such solar cells.