Low-Temperature High-Frequency Capacitance Measurements of Deep-and Shallow-Level Impurity Center Concentrations

A simple method is proposed and demonstrated for the determination of a minute amount of deep-level impurities in the transition region of p-n junctions from the high-frequency capacitance change when the junction temperature is lowered from room temperature to 77°K and the junction bias is switched to zero and back to the large reverse bias to set the charge trapped at these centers to the equilibrium value. Sensitivity of 1011 atoms/cm3 and 105 total atoms in the depletion layer is demonstrated in junction gettered by phosphorus glass. Examples are also given for Ni- and Audoped silicon diodes and transistors.