InGaN Light-Emitting Diodes With the Inverted Cone-Shaped Pillar Structures

An InGaN-based light-emitting diode (LED) with an inverted cone-shaped pillar structure was fabricated through a plasma dry etching process and a photoelectrochemical (PEC) process. The undercut structure was fabricated through a bandgap-selective PEC etching process that occurred at the InGaN active layer. Then, the inverted cone-shaped pillar structure was formed through a bottom-up crystallographic etching process in a hot potassium hydroxide solution. The light-output power of the LED with an inverted cone-shaped pillar structure had a 42% enhancement compared with the standard LED without the pillar structure at a 20-mA operating current. A higher light intensity of the PEC-treated LED was observed around the mesa-edge region and the pillar structures as a result of a higher light-scattering process occurring at the inverted cone-shaped structure.