Electron transport in dodecylamine capped gold nanocluster films using current sensing atomic force microscope (C-AFM).

Electron transport across cataphoretically deposited dodecylamine capped gold nanocluster rough films on Si(111) substrate is investigated using current sensing atomic force microscopy. Contact mode images depict uniform deposition of agglomerates of gold nanoparticles. The current images display strong correlation with topographic images. The I-V measurement on a single agglomerate of approximately = 250 nm size at different forces exhibits force dependent threshold voltage. The electron transport from tip to sample is found to be ohmic in contrast to that from sample to tip which, exhibits Fowler-Nordheim behavior up to 35 nN force. At higher forces, the I-V behavior could be attributed to other electron transfer processes such as Schottky/Poole-Frenkel or trapping/detrapping, although no exact mechanism could be identified. The results are discussed in the light of models based on Coulomb blockaded collective charge transport in nanoparticle arrays duly accounting for the potential role of the capping layer.