Electrical properties of Te-rich, Cd-rich and hydrogen-exposed polycrystalline CdTe thin films

Abstract

Polycrystalline films of CdTe, stoichiometric, Te-rich, and Cd-rich, were grown using a vacuum evaporation technique on glass substrates kept at room temperature. The as-grown films were exposed to hydrogen gas at high pressure (200-500 PSI). Measurements of DC conductivity in the temperature range 77-300K, X-ray diffraction studies and electron probe microanalyses were made on these films. The conductivity data for the stoichiometric, Te-rich and Cd-rich films in the low temperature region have been analysed for variable range hopping conduction on the basis of Mott's model. The analysis of the high temperature conductivity data for Te-rich and hydrogen-exposed films has been based on Seto's model of thermionic emission. It is found that addition of Te and Cd improves the conductivity of the films by four and six orders of magnitude respectively. However, the density of trap states near the Fermi level, N(EF), also increases with increase of Cd and Te content. In the case of hydrogen-exposed films the conductivity decreases with increase of gas pressure.

Tuning Electrical and Optoelectronic Properties of Single Cadmium Telluride Nanoribbon

“…The relationship of increasing %Te resulting in decreasing resistivity is also consistent with our previous results . In addition, this trend has been observed previously in p-CdTe electrodeposited thin films in which a similar inverse correlation between resistivity and deposition potential was correlated, , and a similar result on higher Te content giving lower resistivity of CdTe thin films was observed …”

“…21 In addition, this trend has been observed previously in p-CdTe electrodeposited thin films in which a similar inverse correlation between resistivity and deposition potential was correlated, 25,26 and a similar result on higher Te content giving lower resistivity of CdTe thin films was observed. 27 The I sd −V sd characteristics of a 64% Te-rich and a 75% Terich CdTe device are evaluated with gate voltage (V g ) set at V g = 0, V g = −40 V, and V g = 40 V (Figure 3A). When a V g of −40…”

Photoconductivity and Relaxation Dynamics in Sonochemically Synthesized Assemblies of AgBiS2 Quantum Dots

“…The presently studied system belongs to the class of low-dimensional polycrystalline materials. Therefore, in addition to the increase of the free charge carrier concentrations due to internal photoelectric effect, also the photoinduced modulation of grain boundary barrier heights could be important in determining the overall dynamics of charge carrier transport through the films. − The photomodulation of the intercrystalline boundary barriers in the presently studied n-type semiconductor is explained as follows. In the absence of photoexcitation by external light source, in n-type semiconductor with acceptor-type surface states, band bending on the surface occurs as a result of the spontaneous negative charge transfer from the bulk part of the semiconductor to the surface.…”

“…This suggests that direct band-to-band electronic transitions contribute to the internal photoelectrical effect in the presently studied thin films, which is in line with the conclusions about the band structure of AgBiS 2 thin films derived on the basis of the optical spectroscopy data given in our previous paper, 46 and also with the available literature data for this material. 50,51,[53][54][55][56][57] To quantitatively characterize the mentioned transitions, linear least-squares interpolations of the ((∆σ st. / ∆σ st.,max. ) × hν) 2 vs hν dependencies in the relevant energy range were carried out.…”

A Study of Photophysics, Photoelectrical Properties, and Photoconductivity Relaxation Dynamics in the Case of Nanocrystalline Tin(II) Selenide Thin Films

“…Following Mott, , the VRH mechanism generates the following dependence of σ on T : where σ 0 and T 0 are constants. At relatively higher temperatures (usually above 250 K, , which depends on the Debye's length, i.e., the D / L D ratio), the predominant charge-transport mechanism involves thermionic emission over the crystal (grain) boundaries. In the case of studied, chemically deposited nanocrystalline SnSe thin films, the calculated Debye length (for a usual doping concentration of 10 23 m -3 and taking the average literature value for ε r in the case of SnSe of 15) is close to 15 nm.…”