A new model for the p-n junction space charge region capacitance

Depletion-approximation-based junction capacitance versus voltage characteristics are adequate for reverse bias but, contrary to experiments and computer simulations, predict an infinite capacitance when the applied voltage equals the built-in potential. A new, physically justified model for the semiconductor space charge region capacitance is derived. This new model takes only three input parameters, i.e., the zero bias capacitance, the built-in potential and the junction grading coefficient, thus eliminating the fitting parameter FC currently used in SPICE (Simulation Program with IC Emphasis). This new model eliminates the singularity found in the depletion approximation model and is applicable for any applied voltage. This new model is compared with capacitance results extracted from the PSPICES device simulator and with earlier capacitance model formulations.<
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