Analysis of a reverse-biased linearly graded junction with high concentration of deep impurities

The numerical solution of the Poisson's equation, applied to the case of a linearly graded junction with a high concentration of deep centres, has afforded an explanation of the anomalous behaviour of the low temperature, high frequency transistion capacitance measurements of a Si diode doped with Pt. The origin of this anomaly is found in the oscillating character of the charge distribution produced in the space charge layer when the concentration of deep impurities is higher than that of the basic dopants. The theoretical and experimental results were fitted in order to obtain the values of the deep level concentrations, which would have been impossible with classical capacitive techniques.