Mott-Schottky equation flat band potentials

The flat band potentials of a semiconductor can be determined from the photocurrent-potential relationship for small band bending [equation (4.2.1)], or derived from the intercept of Mott-Schottky plot [equation (4.2.2)] using following equations... 

Equation 6 indicates that a plot of l/C against U gives a straight line with a slope of l/qsQSsNi)), which is termed the Mott-Schottky plot, as mentioned earlier. The extrapolation of the straight line to 1/C = 0 gives ((7fi, 4- 7 / ). Therefore, the plot can be used to determine the flat band potential t/ft. The donor density Vd (or the acceptor density Va) can also be determined from the slopes of the plots. Figure 4 shows examples of Mott-Schottky plots, obtained for n-Si(lll) and n-Si(lOO) electrodes in 7.1 M... 

Mott-Schottky analysis. Eq. 1 is the key to a quantitative description of capacitance-voltage and photocurrent measurements at semi-conductor/electrolyte-interfaces. Capacitance measurements are commonly done as Mott-Schottky analysis that allows the determination of two important semiconductor properties the flat band potential Ufb and the doping concentration N. The method is based on the measurement of the capacitance of the space-charge layer and the analysis of the data according to the Mott-Schottky-equation, which treats the space charge layer in the semiconductor as the distance of the plates in an ideal condenser ... 

From eq. (3), it is evident that a plot of 1/C v.s. electrode potential U gives a straight line, from the slope the doping concentration N (N = Nd donor concentration for n-type semiconductors, N = Na acceptor concentration for p-type semiconductors) can be obtained, if s is known. An extrapolation to 1/C O yields the flat band potential 11. An example is shown in Fig. 3b, with a Mott-Schottky plot measured on n-Si(lOO) in 1 10 NH4OH solution. An evaluation according to the Mott-Schottky equation yields the n-type character due to the positive slope, a flat-band potential of -1.1 V vs. SCE, and a doping density of 1.5-1.6 x 10 cm. ... 

The famous Mott-Schottky relationship [25,26] in Eq. 5-21 represents a different potential-dependent surface capacitive case. This relationship was derived to express the electronic properties of passive capacitive films of constant thickness formed on metals. The methods based on the Mott-Schottky equation have been widely used as a valid tool to determine semiconductive character and dopant density of the surface films in the semiconductor industry and in corrosion studies. The change of the space-charge layer capacitance of the passive film (or space charge distribution) depends on the difference between the applied DC potential V and flat band potential V g characteristic of the surface film, where Np = concentration of donors (or acceptors) or "doping density" ( 10 - lO cm" ), and Cg = 1.6 KT C electron charge ... 

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