Enhanced charge-transport in surfactant-free PbSe quantum dot films grown by a laser-assisted spray process

A laser-assisted spray process was developed to deposit surfactant-free PbSe quantum dot (QD) films directly on a substrate. These QDs are in close contacts with each other, forming a percolation path for charge transport. Absorption spectroscopy confirmed the quantum confinement of the deposited particles. Room temperature current-voltage measurements across a 2 mu m tunnel junction formed by the QDs produced a power-law dependence of the form I proportional to V-2.25, which describes a percolation path of dimensionality slightly above two dimensions. Temperature dependent conductance studies showed thermally activated transport at high temperatures and temperature independent tunneling, followed by previously unobserved metallic conduction at low temperatures. (C) 2009 American Institute of Physics. [doi:10.1063/1.3233926]