Vertical chip of GaN-based blue light-emitting diode

We demonstrate a sapphire-etched vertical-electrode nitride semiconductor (SEVENS) light-emitting diode (LED) fabricated by a selective wet etching between sapphire substrate and GaN-based layers. The SEVENS-LED performance is enhanced compared to a conventional NiAu lateral-electrode (LE) GaN-based LED formed on the same sapphire substrate. The 20-mA light-output power and reverse electrostatic discharge (ESD) pulse amplitude of SEVENS-LED are approximately 4.5 mW and 2000 V, respectively. The variation of peak wavelength with increasing a junction current is less for the SEVENS-LED than for the LE-LED. The improved LED performance is attributed to changing a lateral electrode to a vertical electrode although the sapphire substrate is not transferred to a conducting substrate.