Negative capacitances in low-mobility solids

The neg. capacitance as often obsd. at low frequencies in semiconducting devices is explained by bipolar injection in diode configuration. Numerical calcns. are performed within the drift-diffusion approxn. in the presence of bimol. recombination of arbitrary strength. Scaling relations for the characteristic frequency with bias, sample dimensions, and carrier mobilities are presented in the limits of weak and strong recombination. Finally, impedance measurements conducted on a light-emitting diode and photovoltaic cell based on low-mobility org. semiconductors are modeled as a function of bias and temp., resp. [on SciFinder (R)