Nitride-Based Light-Emitting Diodes with a Radiated-Cone-Shaped Structure at GaN/Sapphire Interface

Abstract

InGaN-based light-emitting diode (LED) with a radiated-cone-shaped structure at GaN/sapphire interface was fabricated through a laser drilling process and a photoelectrochemical (PEC) wet etching process. The inverted cone-shaped GaN structure was formed around the laser-drilled hole as a light scattering structure to enhance the light extraction efficiency at central mesa region. The light output power of the PEC-treated LED structure had an approximate 19% enhancement when compared to a conventional LED at 20 mA. The photoluminescence peak wavelength of the InGaN active layer was slightly blueshifted from 458.4 nm for the conventional LED to 449.9 nm for the treated-LED that could be caused by partially reducing the compressive strain induced piezoelectric field by forming the radiated-cone-shaped structure at GaN/sapphire interface. High light emission intensity for the treated LED structure was observed around the laser-drilled hole pattern as a result of a higher light-scattering process occurring at the radiated-cone-shaped structure for the InGaN-based LED applications.