Efficient Charge Extraction out of Nanoscale Schottky Contacts to CdS Nanowires
Charge recombination dynamics in semiconductor nanostructures is of vital importance for photovoltaic or photodetector device applications. We use local photocurrent measurements to explore spatially separated drift- and diffusion-currents close to the edge of gold contacts on top of cadmium sulfide nanowires. By theoretical modeling of the experimental photocurrent profiles, the electron diffusion length and lifetime in the wires are obtained to 0.8 mu m and 1 ns, respectively. In contrast to bulk devices, the nanoscale dimensions of the involved Schottky contacts enable a highly efficient charge carrier extraction from below the electrodes. This finding paves the way for designing nanostructured optoelectronic devices of improved performance.