Enhanced Light Output Power in InGaN Light-Emitting Diodes by Fabricating Inclined Undercut Structure

The -based light-emitting diode (LED) with an inclined undercut structure is fabricated through the photoelectrochemical two-step process to increase light extraction efficiency. In the first step the sidewall-undercut structure at the p-type and n-type interface is created by selective wet oxidation on an n-type surface in pure solution. In the second step an inclined undercut structure through a crystallographic wet-etching process is formed by immersion in hot solution. This crystallographic wet-etching process can remove the layer and form a p-type stable plane, n-type stable plane on the mesa sidewall. This inclined p-type plane of LED structure can provide the higher overlap of incident light beam core and extraction core overlap on the mesa sidewall, and the total light output power of the treated LED is 2.10 times higher than the standard LED. Consequently, this inclined undercut LED structure is suitable for high-efficiency nitride-based LED application.