Separation and analysis of diffusion and generation components of pn junction leakage current in various silicon wafers

An analytical method to separate the diffusion and generation components of pn junction leakage currents is developed. The voltage dependence between reverse current and capacitance in pn junctions is measured, and an approximately linear relationship between current density (J) and depletion width (W) is derived. In this relationship, the diffusion component corresponds to linearly extrapolated value of J at W=0, and the generation component corresponds to the rate at which J increases with W as voltage is applied. This method allows both components of the leakage current to be obtained for Czochralski, epitaxial, and intrinsic gettering wafers. Separated diffusion components strongly depend on silicon wafers mainly due to the change of minority carrier density and the diffusion of minority carriers. On the other hand, the generation component increases with increases in the electric field applied to the junction for all wafers. We found that this electric field effect on the generation component can be explained by the Poole–Frenkel mechanism.