Impurity centers in PN junctions determined from shifts in the thermally stimulated current and capacitance response with heating rate

Abstract

A theory is developed for the thermal response of pn junction current and capacitance where the junction contains deep impurity centers. Measurements lead to values for the energy level, emission coefficient and concentration of these centers. Energy levels and emission coefficients are found from shifts in either the current maxima or the capacitance slope maxima with heating rate. The theory indicates that the heating rate may be non-linear and that energy levels may be found independent of the emission coefficient. The analysis accounts for the possibility that only a portion of the space-charge region may contain charged deep centers. This allows the identification of centers in a small segment of the space-charge region. In addition, the analysis allows for the motion of the space-charge width as deep centers discharge. A gold-doped silicon n + p junction is used to verify the theory. The experimental hole emission parameters for the gold donor are in good agreement with those values obtained by other workers using different methods.