Schottky barriers to colloidal quantum dot films

We elucidate experimentally a quantitative physical picture of the Schottky barrier formed at the junction between a metallic contact and a semiconducting colloidal quantum dot film. We used a combination of capacitance-voltage and temperature-dependent current-voltage measurements to extract the key parameters of the junction. Three differently processed Al/PbS colloidal quantum dot junction devices provide rectification ratios of 10(4), ideality factors of 1.3, and minimal leakage currents at room temperature. The Schottky barrier height is 0.4 eV and the built-in potential 0.3 V. The depletion width ranges from 90 to 150 nm and the acceptor density ranges from 2x10(16) to 7x10(16) cm(-3). (c) 2007 American Institute of Physics.