Semiconducting behavior of Ag2Te thin films and the dependence of band gap on thickness
TL;DR: In this paper, the electrical resistance of Ag2Te films has been measured as a function of temperature during heating, which was carried out immediately after the film formation, and the observed exponential decrease of resistance with temperature up to the transition point points to the semiconducting nature of the low temperature polymorph of ag2Te.
Abstract: Thin films of Ag2Te of various thicknesses in the range 500–1500 A have been prepared by thermal evaporation of the compound under vacuum on clean glass substrates held at room temperature. The electrical resistance of the films has been measured as a function of temperature during heating, which was carried out immediately after the film formation. The observed exponential decrease of resistance with temperature up to the transition point points to the semiconducting nature of the low temperature polymorph of Ag2Te. The band gap of the low temperature phase is calculated for various thicknesses of the films and it is found that the band gap is a function of film thickness, increasing with decreasing thickness. The increase in the band gap, which was found to be inversely proportional to the square of the film thickness, is attributed to quantization of electron momentum component normal to film plane.
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TL;DR: In this paper, the authors measured the optical absorption in the wave number range 500-4000 cm−1 and evaluated the band gap as a function of film thickness and deposition temperature, and showed that the data indicate absorption through direct interband transition with a band gap of around 0.216 eV.
Abstract: Sn0.2Bi1.8Te3 thin films were grown using the thermal evaporation technique on a (001) face of NaCl crystal as a substrate at room temperature. The optical absorption was measured in the wave number range 500–4000 cm−1. From the optical absorption data the band gap was evaluated and studied as a function of film thickness and deposition temperature. The data indicate absorption through direct interband transition with a band gap of around 0.216 eV. The detailed results are reported here.
9 citations
TL;DR: In this paper, the optical properties of monoclinic Ag2Te crystals were studied in a wide range (3.7 −meV −6.2 −eV) of photon energies.
8 citations
TL;DR: In this paper, an increase in the energy gap with decreasing film thickness has been observed and studied in case of thin films of stibnite (Sb2S3), which is attributed to quantum effects.
7 citations
TL;DR: In this article, thin films of InSb0.97Bi0.03 were grown at room temperature on (001) NaCl crystal substrates under a pressure of 10−5'Pa using the thermal evaporation technique.
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TL;DR: In this paper, linear and nonlinear optical studies of thin indium selenide films are prepared using thermal evaporation technique, which is intensively researched due to its specific characteristics.
6 citations
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TL;DR: In this paper, the barrier theory of the infrared photoconductivity of PbS films is discussed, according to which the high resistance of the films arises from $n √ √ n √ ϵ barrier at the surfaces between the crystallites forming the films, the barriers being formed in the oxidizing process used in preparing the films.
Abstract: The barrier theory of the infrared photoconductivity of PbS films is discussed, according to which the high resistance of the films arises from $n\ensuremath{-}p\ensuremath{-}n$ barriers at the surfaces between the crystallites forming the films, the barriers being formed in the oxidizing process used in preparing the films. Under the action of light, electron hole pairs are formed, these carriers become trapped in the $n$- and $p$-type regions, respectively, the resulting charge density lowers the barriers, and hence the conductivity is increased. This theory is worked out quantitatively, and compared with experimental results of Mahlman on films of the type actually used as sensitive photoconductors. The theory shows good qualitative and quantitative agreement with experiment in numerous respects, including the explanation of the dark conductivity of the films and its dependence on temperature, the photoconductivity as a function of irradiance and temperature, the time constants involved in the rise or decay of the photoconductivity, and the short-wave limit of the photoconductivity. In working out the theory of the barrier model, we use the properties of the bulk material as determined by Petritz and Scanlon, and the properties of the films are found to be consistent with our knowledge of the behavior of the bulk material.
157 citations
TL;DR: In this paper, the Seebeck coefficient α, electrical conductivity σ, and thermal conductivity K data are given for a number of Ag2Te specimens measured at room temperature, and the maximum value observed for the figure of merit α2σ/K was 1.3×10−3°C−1.
Abstract: The Seebeck coefficient α, electrical conductivity σ, and thermal conductivity K data are given for a number of Ag2Te specimens measured at room temperature. The maximum value observed for the figure of merit α2σ/K was 1.3×10−3°C−1. The relationship between K and σ was linear, and Kel could be expressed approximately by (π2/3) (k/e)2σT. Kph was found to be 0.72×10−2 w cm−1°C−1. There was no evidence of an ambipolar diffusion contribution to K. It is suggested that the small energy gap (0.02 ev) previously determined in this compound could account for the absence of a measurable ambipolar diffusion effect, the degeneracylike behavior of Kel, and the relatively low values of the Seebeck coefficient.
75 citations
TL;DR: In this paper, the Hall coefficient, resistivity, and Seebeck coefficient of $n$-and $p$-type specimens of Ag2Te have been measured over the temperature range from 55 to 300.
Abstract: The Hall coefficient, resistivity, and Seebeck coefficient of $n$- and $p$-type specimens of ${\mathrm{Ag}}_{2}$Te have been measured over the temperature range from 55 to 300\ifmmode^\circ\else\textdegree\fi{}K. These results indicate that the compound is highly degenerate over the whole temperature range studied. Calculations were made of the effective masses, mobility ratios, and energy gap and gave order of magnitude values.
45 citations