Photoconductive gain in patterned nanopillar photodetector arrays

We report on the photoconductance characteristics of indium tin oxide (ITO)-GaAs photodetectors based on patterned nanopillar (NP) arrays grown by metal-organic chemical vapor deposition. The NPs are partially encapsulated by commercially available polymer to allow transparent ITO contact to exposed NP tips. Under illumination, the NP photodetectors demonstrate photoconductive gain in both forward and reverse bias. The mechanism for photoconductive gain is attributed to both the lowering of the Schottky barrier at the ITO-GaAs interface by photogenerated holes, and also the increase in the conduction volume of the NPs under illumination. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3517491]