Tunneling-Hopping Transport Model for Reverse Leakage Current in InGaN/GaN Blue Light-Emitting Diodes

The nature of charge transport in GaN-based light-emitting diodes (LEDs) under reverse biases still remains elusive as the bias- and temperature-dependent characteristics of the current can hardly be formulated using a single transport mechanism. In this letter, based on numerical fitting, we develop a combined tunneling-hopping transport model to describe the complete electrical characteristics of the reverse leakage current in InGaN/GaN blue LEDs. This model depicts that the current behaviors are majorly limited by the charge transport process through the depletion region near the neutral n-side, where electrons at the valance band are ready to tunnel into the unoccupied localized gap states in neighborhood near the electron quasi-Fermi level (E
_fn
), followed by variable-range hopping or nearest-neighbor hopping via these localized states along a relatively constant E
_fn
, depending on temperature.