I have made some semiconductor films on Si( highly doped ) and ITO/glass substrates via electrochemical deposition. As this method can only allow film deposition on conductive substrates, I am wondering how to measure the conductivity (mobility )of the semiconductor film alone ? Will hall measure be okay ? If so, how to subtract the substrate? Thanks very much !
dear Xiaojie Xu ; you can use four-point probe measuring device, Loresta Resistivity Meter, model MCP T400, from Mitsubishi, This meter measures the electrical resistance under 1.99 x 107 Ω. The electrical resistivity of the coated samples can be measured by contacting its surface with these four pins.
Dear Xu,
You can choose either two probe or four probe mobility measurements. You can accurate values in this technique, and it is the basis of many practical application and devices such as magnetic field measurements, and position and motion detectors. .
Please see the following links.
http://courses.washington.edu/phys431/hall_effect/hall_effect.pdf
Venkata Ramana Mudinepalli Hi Venkata, thanks so much for the answer and link. It is very helpful !
Sorry, I do not agree. Hall effect or direct four probe measurements ( Van der Pauw method) wouldn't work on conductive substrate(may be on Si, if bulk substrate doping provide conductance significantly less than film). You can try optical methods - ellipsometry or reflectance.
As Oleg A Nerushev. The van der Pauw (vdP) technique permits the measurement of resistivity for homogeneous[1-8] (and isotropic, in all directions, thin) samples of arbitrary shape[9], with a constant thickness; so, the vdP-technique is always helpful, but only, for (simple cases of isotropic, single) samples having a uniform[1-8] resistivity.
1. L. J. van der Pauw, Philips Res. Rep. 13, 1 (1958).
2. L. J. van der Pauw, Philips Tech. Rev. 20, 220 (1958–1959).
3. P. M. Hemenger, Rev. Sci. Instrum. https://doi.org/10.1063/1.1686224 44, 698 (1973).
4. D. W. Koon and T. G. Castner, Phys. Rev. B https://doi.org/10.1103/PhysRevB.41.12054 41, 12054 (1990).
5. A. K. Raychaudhuri, Phys. Rev. B https://doi.org/10.1103/PhysRevB.44.8572 44, 8572 (1991).
6. G. J. Snyder, T. Caillat, and J. P. Fleurial, Phys. Rev. B https://doi.org/10.1103/PhysRevB.62.10185 62, 10185 (2000).
7. D. W. Koon, A. A. Bahl, and E. O. Duncan, Rev. Sci. Instrum. https://doi.org/10.1063/1.1140423 60, 275 (1989).
8. D. W. Koon and C. J. Knickerbocker, Rev. Sci. Instrum. https://doi.org/10.1063/1.1149149 69, 3625 (1998).
9. The contacts should also be sufficiently small, depending on the required accuracy, and placed on the periphery of the sample.
I agree with Oleg A Nerushev , but I think that the best way to obtain all electronic properties of a semiconductor film on a conductive substrate is with Electrochemical Impedance Spectroscopy analysis.
Regards.
If you want to get a more accurate conductivity, you can probably try deposit a thin layer of semi- insulating (or very low-doped) semiconductor film and than deposit your target film which has higher doping level or conductivity. Hall measurement is always the best way.
Dear Xiaojie,
It is very difficult to perform electrical measurement of a film deposited on conducting substrate. Since electrons always follow least resistive path, it will travel through ITO and you will eventually get conductivity of ITO instead of your material. However, we have tried to address this issue in our recent publication. Please go through it for detailed information.
Thank you,
Article Hall Mobility of As-Grown Cu2O Thin Films Obtained Via Elect...
Yes, I agree with Rafael Valentin Tolentino-Hernandez, I think that the Electrochemical Impedance Spectroscopy (EIS) technique makes it possible to estimate the electronic properties of thin semiconductor films (charge carrier concentrations ...).
Yes, it is very difficult to perform electrical measurements of a film deposited on conducting substrate. Just, I agree with Amor Azizi, the Electrochemical Impedance Spectroscopy (EIS) technique, with the mott-schotkey measurement you can estimate the flat band energy and the charge carrier concentrations.
For detailed information, please see the following link:
https://www.researchgate.net/publication/323374820_Electrodeposition_of_nanostructured_g-MnO2_film_for_photodegradation_of_Rhodamine_B
Thank you,
Hi, it is not possible to make an accurate measurement just with the Hall effect. But you can use Electrochemical Impedance Spectroscopy to get dominant charge carrier concentration. Also, I think it is possible to subtract the film resistivity by performing the Hall effect measurement to bare ITO (or FTO) and the thin-film on ITO assuming that the thin-film and ITO are parallel resistances. I read a similar approach in some research papers on dielectric/metal/dielectric (D/M/D) thin films. Once you get the dominant carrier concentration and the resistivity then you can calculate the carrier mobility.
Article Transparent Heat-Mirror Films of TiO2/Ag/TiO2 for Solar Ener...
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