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4 Measurement of Work Function
(a)
(b)
(c)
Fig. 4.25 Schematic illustration of principle of work function difference measurement by diode
method: a setup of measurement system, b band diagram under zero bias; c band diagram under
BP bias, where there is no contact potential difference (see text for explanation)
Fig. 4.26 Schematic
illustration of the
relationship between BP bias
voltage and diode current in
the diode method (see text
for explanation)
for a certain current to flow is obtained. Then, the BP bias (V ) required to obtain the
same current for the specimen is measured. The difference, V − V 0 , is the contact
potential difference between the reference and the specimen.