Schottky barriers to colloidal quantum dot films

Abstract

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 $\mathrm{Al}∕\mathrm{Pb}\mathrm{S}$ 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 $0.4\mathrm{eV}$ and the built-in potential $0.3\mathrm{V}$ . The depletion width ranges from $90\text{to}150\mathrm{nm}$ and the acceptor density ranges from $2\times {10}^{16}\text{to}7\times {10}^{16}{\mathrm{cm}}^{-3}$ .