Nanocrystalline PbTe Films

This work deals with the impact of nano-scale morphology on the photoelectric properties of n-type PbTe thin films. Nano-structured thin films were prepared by varying the rate of nucleation as a function of the nature and the temperature of the substrates. The broken bonds at the grain boundaries generate acceptor states in n-type films, capture electrons from the interior of the grains and give rise to p-type inversion layers between adjacent grains. A model based on the assumption that the current is exclusively due to the motion of holes in the inversion channels along the grain boundaries, is proposed to explain the temperature dependence of photoelectric properties. This approach allows designing infra-red detectors based on nano-crystalline lead chalcogenide films at the wavelength up to 4-5 μm that don't require cryogenic cooling.