Equilibrium self-assembly of close-packed ordered PbTe nanocrystal thin film and near-infrared photoconductive detector

Abstract

A PbTe thin film with near-infrared photoconductive characteristics is assembled from monodisperse PbTe nanocrystals (NCs). Monodisperse PbTe NCs show large absorption tunability (>400 nm) by a rapid injection solution-phase synthesis route. In order to obtain smooth close-packed NC thin films on a Si/SiO₂ substrate with Ti/Au contacts the equilibrium self-assembly method is employed, which is conveniently controlled by adjusting the velocity of the argon flow and the evaporation temperature. According to atomic force microscope (AFM) and scanning electron microscope (SEM) analysis, we propose a schematic diagram of the PbTe NC assembly process to form the PbTe NC film. The PbTe NC thin film exhibits a good photoconductive gain after ethylenediamine treatment. This phenomenon thus illustrates that the PbTe NC thin film has near-infrared photoconductive characteristics.