Current-voltage characteristics of InGaN/GaN blue light-emitting diodes investigated by photovoltaic parameters

Abstract

We investigate the current-voltage (I-V) characteristics of InGaN/GaN multiple-quantum-well blue light-emitting diodes (LEDs) to analyze the additional voltage drop outside the active region. We theoretically examine and measure the short-circuit current versus the open-circuit voltage (I-SC-V-OC) obtained by photoexcitation and compare them with the I-V obtained by electrical injection. The I-SC-V-OC curve shows the ideal I-V characteristics that do not contain the deviation from the exponential behavior. In the ideality factor obtained by differentiating the I-SC-V-OC curve, the increase of ideality factor due to the series resistance is not observed. The slope of the additional voltage drop Delta V versus current curve shows a nonlinear behavior, indicating that a simple ohmic voltage drop is not sufficient to explain Delta V. From these observations, it is concluded that the carrier recombination in the active region plays a non-negligible role in I-V characteristics of LEDs deviating from the ideal behavior. (C) 2018 The Japan Society of Applied Physics