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

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 Δ V versus current curve shows a nonlinear behavior, indicating that a simple ohmic voltage drop is not sufficient to explain Δ 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.