Transport properties and photo‐ conductivity of nanocrystalline PbTe(In) films

Abstract

Microstructure, charge transport and photoelectric properties are studied for PbTe(In) films deposited on amorphous substrates kept at different temperatures Ts during deposition. All the films have a column‐like structure with the mean column diameter increasing from 60 nm at the lowest Ts = ‐120 °C up to 300 nm at the maximal Ts = 250 °C. The substrate temperature increase results in appearance of a preferred orientation of grains and in an inversion of the conductivity type from hole to electron. Electric transport and photoelectric properties of the films were studied in the temperature interval 4.2 – 300 K in DC and AC modes at frequencies varied from 20 Hz up to 1 MHz. The impedance spectra analysis was done in terms of the equivalent circuit model. Modification of charge transport mechanisms is correlated with the variation of microstructure of the films grown at different substrate temperatures. Films with disordered grains possess all features of non‐homogeneous systems, while the films with a preferred orientation of grains are analogous to PbTe(In) single crystals in their transport and photoelectric properties. Mechanisms of the persistent photoconductivity observed in the films are qualitatively distinguished. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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

“…The results of the calculation of m* d from Equation ( 14) were only slightly different from those obtained for bulk single crystals of PbTe [9]. This result, as well as the results of measurements of the optical band gap in the same films [20], made it possible to exclude changes in the band parameters in PbTe films. The observed differences between S and Q N of PbTe films and of the bulk single crystals can be related to the appearance of an additional scattering mechanism.…”

“…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].…”

Discrimination of Conductive Surface Electron States by Laser Terahertz Radiation in PbSe—A Base for Pb$_{1-x}$Sn$_x$Se Topological Crystalline Insulators

“…A commonly accepted model describing the conductivity of polycrystalline lead chalcogenide films is based on an idea of formation of -type inversion layers on the surface of grains possessing the -type conductivity [26], [27]. This idea turned out to be very productive for interpretation of many effects observed in lead chalcogenide films including specific features of the impedance spectroscopy [28], photoconductivity and photoluminescence kinetics [29], [30], conductivity temperature dependence [30]. The data obtained in this paper correspond in general to this concept.…”

Integrated photonics for infrared spectroscopic sensing

“…On the other hand, lead and tin chalcogenides are semiconductors suitable for mid-IR detection. Unlike other narrow-bandgap semiconductors which mandate epitaxially grown single crystals for device fabrication, the polycrystalline form of these chalcogenide semiconductors offer performance comparable or even superior compared to their single-crystalline counterparts due to a unique charge-separating mechanism at grain boundaries [48][49][50][51]. These polycrystalline chalcogenides can be readily deposited via chemical bath deposition [52,53] or thermal evaporation, facilitating monolithic integration of active mid-IR photonic devices on common semiconductor or dielectric substrates [54][55][56].…”