Low-temperature charge transport in photosensitive nanocrystalline PbTe(In) films

Abstract

Abstract.We have investigated conductivity of the PbTe(In) nanocrystalline films in dc and ac modes at temperatures 4.2-300 K in the frequency interval 20 Hz -1 MHz in darkness and under illumination. Conductivity of the as-grown films is determined by charge transport along the inversion channels at the grain surface and activation (or tunneling) through the grain barriers. Persistent photoconductivity appears in the films due to spatial separation of nonequilibrium charge carriers at temperatures lower 150 K. As grown films have been annealed in oxygen at 300 o C and 350 o C. Oxidation at 300 o C leads to resistivity increase, grain barrier height growth and higher photoresponse . Annealing at 350 o C results in resistivity reduction and photoresponse decrease. The main contribution to charge transport at low temperature in this case is related to the hopping conductivity along the inversion channels.

A Review of Nanocrystalline Film Thermoelectrics on Lead Chalcogenide Semiconductors: Progress and Application

“…Various methods including decomposition at solid-state synthesis [6] and preparation of nanopowders [7] are used for the preparation of nanostructured materials. In this work, the flash evaporation technology method, first developed by Prof. Z. Dashevsky for Bi 2 Te 3 based compounds [10,11], was used for the preparation of the lead chalcogenides (PbTe, PbTe, PbS) semiconductor films [12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The setup for the film preparation is presented in Figure 1 [11].…”

“…All films have negative values of the Hall coefficient over the entire temperature range, which is related to the electronic conductivity (n-type) in PbTe films. The Hall concentration n H of the prepared Pb 1−x In x Te films was determined using Equation (17). For all film specimens up to heavily doped Pb 0.97 In 0.03 Te film, the Hall electron concentration does not exceed in the order 10 18 cm −3 .…”