MS-682 FOUR PROBE METHOD APPARATUS

Resistivity of Semiconductor by Four Probe Method at different
temperatures and determination of the Band-gap .The Four Probe
Method is one of the standard and most widely used methods for
the measurement of resistivity of semiconductors. The four probes
are collinear. The error due to contact resistance, which is especially
serious in the electrical measurement on semiconductors, is
avoided by the use of two extra contacts (probes) between the
current contacts. In this arrangement the contact resistance may all
be high compare to the sample resistance, but as long as the
resistance of the sample and contact resistance are small compared
with the effective resistance of the voltage measuring device
(potentiometer, electrometer or electronic voltmeter), the
measured value will remain unaffected. Because of pressure
contacts, the arrangement is also especially useful for quick
measurement on different samples or sampling different parts of
the same sample