Resistivity and thermopower measurements were performed on thin films of Bi2(Te0.8Se0.2)3 prepared by flash evaporation technique. Applying the Jain-Verma theory to the experimental data of Bi2(Te0.8Se0.2)3, scattering index parameter was evaluated. The value of scattering index parameter was found to lie between -0.3 and -0.2. This indicates the presence of other scattering mechanisms, in addition to the lattice scattering. © 2002 Elsevier Science B.V. All rights reserved.

V. Damodara Das

Annealing

Bismuth compounds

Thermal conductivity of solids

Thermoelectricity

X ray diffraction analysis

SCATTERING INDEX PARAMETERS

Thin films

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Determination of the nature of principal scattering mechanism in well-annealed vacuum deposited thin films of the ternary thermoelectric material Bi2(Te0.8Se0.2)3

Thin Solid Films

Thin films of (Bi0.25Sb0.75)2Te3 with 2% excess Te of different thicknesses were prepared by the flash evaporation technique. Electrical resistivity and thermoelectric power were measured for different thickness films and at different temperatures. Applying Jain-Verma theory of carrier energy dependent relaxation time, thermoelectric data of thin films were analysed to understand the nature of scattering mechanisms in this thermoelectric material. The scattering parameter b was calculated from the thermoelectric and resistivity data. This gives us an indication about the nature of scattering processes in the before mentioned composition thin films. It is found from such an analysis of the thermoelectric data of thin films of the alloy with 2% excess Te that the scattering index parameter b varies in this material thin films from -0.2 to -0.1 and to positive values at higher temperatures. © 2002 Elsevier Science Ltd. All rights reserved.

Materials Research Bulletin

Study of scattering of charge carriers in thin films of (Bi0.25Sb0.75)2Te3 alloy with 2% excess Te

The Jain-Verma theory has been applied to the thermoelectric data of vacuum flash-evaporated and annealed polycrystalline thin films of (Bi0.5Sb0.5)2Te3 alloys of different thicknesses to study the nature of principal carrier scattering mechanism and also to know the extent of other scattering mechanisms, simultaneously. It is found that the value of the energy dependent scattering index parameter lies between -0.45 and -0.4. This indicates that, even though the principal scattering mechanism in the films is the normal lattice scattering, other scattering like 'impurity' scattering, surface scattering and grain boundary scattering may be present. © 2001 Elsevier Science Ltd. All rights reserved.

Solid State Communications

Thermoelectric behaviour of (Bi0.5Sb0.5)2Te3 semiconducting alloy thin films

Thin films of Bi2Te2Se1 of various thicknesses have been deposited on clean glass plates using the flash evaporation technique. Electrical resistance and thermoelectric power measurements have been carried out on these films in the temperature range 300-485 K. The thickness dependences of electrical resistivity and thermoelectric power of the films have been analyzed using the effective mean-free path model. The thickness dependence of activation energy of the films is explained by Seto's polycrystalline model. Various material parameters such as mean-free path and Fermi energy have been calculated from the analysis of experimental data. The thermoelectric power factor of the films has been calculated using the measured electrical resistivity and thermoelectric power values. © 1998 American Institute of Physics.

Fulltext

Journal of Applied Physics

Size and temperature dependence of electrical resistance and thermoelectric power of Bi2Te2Se1 thin films

Antimony thin films of different thicknesses have been vacuum-deposited onto cleaned glass substrates held at room temperature, and their thermoelectric power and electrical resistivity have been evaluated as functions of temperature and thickness. The Jain-Verma theory of the size effect on the thermoelectric power of thin films has been applied to the experimental data to understand the nature of the scattering mechanism in antimony thin films. The carrier mean free path Ig and the Seeback coefficient Sg of the bulk (with thin film microstructure) have been evaluated at room temperature from the resistivity-thickness and thermoelectric power-thickness plots, respectively, as 1200 Å and 30.1 μVK-1. Using these values Sf/Sg, the thermoelectric power of the films (in the units of Sg, as given by the Jain-Verma theory has been plotted as a function of thickness t/Ig (in units of Ig) for different values of the scattering parameter b to generate a family of curves. By finding out on what curve or curves the experimental thermoelectric power values lie, the scattering parameter has been evaluated to be -0.2, so that the relaxation time τ varies as τ=a E-0.2 in antimony thin films. It is inferred from this that the major scattering process in our antimony thin films is lattice scattering even though other scattering processes also occur to a lesser extent in the films in the temperature range studied. © 1990.

Vacuum

Nature of principal scattering mechanism in well-annealed antimony thin films-analysis from thermoelectric data

Thin antimony films of thicknesses in the range 30 to 200 nm have been vacuum deposited on glass substrates at room temperature. After annealing for about an hour at 500 K, the thermoelectric power and electrical resistivity were measured in vacuum as a function of temperature. The thermoelectric power and electrical conductivity data were combined and simultaneously analysed using the effective mean free path theory of size effect in thin films developed by Tellier and Pichard et al. In addition, their temperature dependence was also analysed. It was found that the thermoelectric power is positive and increases with increasing temperature and is inversely proportional to the thickness of the film. The electrical resistivity was found to be temperature dependent with the temperature coefficient of resistivity being positive, and inversely proportional to the thickness of the film. Analysis combining the data from the thermoelectric power and electrical conductivity measurements has led to the determination of mean free path, carrier concentration, effective mass, Fermi energy and the parameter {Mathematical expression} The data were analysed for least squares fitting by local functions, such as the spline functions, which eliminates possible errors in conventional least squares fitting of data using non-local functions valid throughout the range. © 1989 Chapman and Hall Ltd.

Journal	Thin Solid Films
ISSN	00406090
Open Access	No