Extracting the inherent ideality factor of a diode from electrical current-voltage characteristics

Abstract

The ideality factor of a diode gives the information on the current conduction or recombination processes occurring inside the device. The ideality factor obtained from the electrical current-voltage (I-V) characteristics by the conventional method is typically masked by the effect of the series resistance at high currents. In this study, from a careful analysis of the I-V characteristics, a new formula that can extract the inherent ideality factor without the effect of the series resistance is presented and experimentally tested with a blue light-emitting diode. The new ideality factor thus obtained is compared with the one by the photovoltaic measurement. The inherent ideality factor of a diode can be extracted by innovatively analyzing the diode equation with the voltage drop outside the junction taken into account. The ideality factor values thus evaluated do not show the masking effect by the series resistance at high currents, as obtained by the conventional formula. image