Drift-diffusion theory of symmetrical double-junction diodes

Using numerical methods, we have calculated the current-voltage characteristics, energy contours and carrier distributions of a symmetrical double junction diode (n⁺nn⁺ and n⁺pn⁺). It is found that the I-V characteristics at low currents and voltages depend greatly on the doping concentration of the base region; at hihg currents, they do not. In that regime, the characteristics bunch together, and can be approximated with remarkable fidelity by the Mott-Gurney law for space-charge controlled conduction in solids. Characteristics are presented for different impurity densities and base widths.