High-efficiency flat-type nitride-based micro-light emitting diodes using local breakdown conductive channel

Abstract

A flat-type p-p light-emitting diode (LED) utilizing a local breakdown conductive channel (LBCC) in nitride semiconductor-based LEDs is introduced to replace n-p LEDs with existing mesa etched structures. The flat-type p-p LED, including the LBCC, exhibits similar light output power in the same injection current as the n-p LED of the conventional mesa structure but at a higher operating voltage. Consequently, the flat-type p-p LED with LBCC has lower wall plug efficiency compared to the mesa structured n-p LED. However, when the LED size is small, the flat-type p-p LED can achieve an optical power and operating voltage similar to the conventional n-p LED. As the LED size decreases, the n-type electrode of mesa-type n-p LED decreases to the similar size to the LBCC, providing an alternative to the operating voltage characteristics and wall plug efficiency. In addition, the junction temperature of the LED decreases as the LED size decreases. Based on these results, it is believed that the flat-type P-P LED can be advantageous for achieving high efficiency in smaller LED chips due to the smaller dry-etched mesa area which contains crystal defects that act as non-radiative recombination centers, and higher heat dissipation capacity.