Hi,
I am trying to calculate the flatband potential and charge carrier density of nanoporous CuO layer by Mott Schottky plot on Gamry reference 600. The CuO layer is deposited on an FTO-coated glass substrate. Working electrode is contacted to the CuO layer, reference and counter electrode are short-circuited and contacted to the FTO coating. Measurements are taken in dry air. The measurements are taken at 100 Hz, 1 kHz, 10 kHz and 100 kHz.
I have two problems:
1. I get different carrier densities for each frequency, depending on the frequency in the order of 10^13 cm^-3 to 10^6 cm^-3. The flat band potential also varies. Why is this so? Is there a "correct frequency" in which one should measure for this type of measurement?
2. In the literature the carrier density of p-CuO is given as 10^17 - 10^20 cm^-3. How can it be that I have such a large deviation in the exponent?
Hi,
as a starting point you may find this publication from Kazimirz Darowicki helpful: Article Selection of Measurement Frequency in Mott-Schottky Analysis...
On the other hand, with nanoporous layers, maybe there´s a problem that you dont know the exact free surface and the evaluation hast to be corrected for that reason...
Best regards,
Andreas
Hello Eyüp,
I recommend to read the Wikipedia article concerning Mott-Schottky plot.
You have to consider surface states. This makes it necessary to analyze the high frequency features (this features correspond the dielectric capacitance). Further more the nanostructures on surface reduce the effective surface. This may an esential reason for the deviations.
With Regard
R. Mitdank
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