Measurement of the drift velocity of holes in silicon at high-field strengths

A method is presented which allows the measurement of the velocity-field relationship of charge carriers in a semiconductor. The device used is a four-layer structure. The mode of operation is based on the injection by punch-through of charge carriers into a long depleted region. The velocity can be determined from the VI characteristic of the device and its geometry. Drift velocity saturation is indicated directly by the form of the characteristic. The method has been applied to the measurement of the high-field velocity of holes in silicon. Technological limitations restricted the measurements to fields above 4 . 10⁴V/cm. From this value up to 11 . 10⁴V/cm the hole velocity is found to be constant and equal to 7.5 . 10⁶cm/s ± 5%.