Does the current always become zero at the flat band potential (Efb ), in the case of a semiconductor-electrolyte system? Do the surface states and impurity states, present in the semiconductor, not play any role?
Why would the current always be zero at the flat band potential? You typically won't be in equilibrium at that point. We get Efb from a Mott-Schottky plot based on the potential-dependence of the capacitance (inverse square of the capacitance actually) arising from the space-charge region. Think about what happens to this region in flat-band conditions. To answer your other question, yes, surface and impurity states influence the capacitance measured with EIS. It's important to be aware of the experimental conditions when measuring EIS so that the circuit model used to extract capacitance from the data is physically meaningful. A common default circuit used is an R-C series circuit, which is not applicable to many situations.
dear Ayan Sarkar,
you may use EIS. A scanning set with VDC polarization around VDC0(iDC=0) will enlight the answer.
Why would the current always be zero at the flat band potential? You typically won't be in equilibrium at that point. We get Efb from a Mott-Schottky plot based on the potential-dependence of the capacitance (inverse square of the capacitance actually) arising from the space-charge region. Think about what happens to this region in flat-band conditions. To answer your other question, yes, surface and impurity states influence the capacitance measured with EIS. It's important to be aware of the experimental conditions when measuring EIS so that the circuit model used to extract capacitance from the data is physically meaningful. A common default circuit used is an R-C series circuit, which is not applicable to many situations.
flat band potential is the open circuit potential at which the current is zero.
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