Modelling of some semiconductor devices with large signal excitation

under large signal conditions, the inherent nonlinearity of semiconductor devices is relatively strong, and numerical methods for the solutions of the system equations seem to be inevitable. In this work, numerical algorithms for time-independent and time-dependent modelling of bipolar devices have been developed and used to study both the internal and terminal characteristics of some n(^+)-p and n(^+)-p-p(^+) diodes over a wide range of operation. The effect of minority carrier lifetime on the characteristics of the devices has been investigated, considering the cases of diodes with the same width, diodes with the same recombination criterion, and diodes with the same lifetime but different recombination criteria respectively. In the frequency domain, we studied the influence of the lifetime in terms of harmonic analysis, by applying the Fast Fourier Transform directly to the solutions. The quasi-static spectra obtained from the exact, and approximated diode characteristics, together with the dynamic spectrum, are shown and considered.