A photoelectrochemical wet mesa etching (WME) process was used to fabricate InGaN-based light emitting diodes (LEDs) as a substitute for the conventional plasma mesa dry etching process. The p-type GaN:Mg layer, InGaN active layer, and n-type GaN:Si layer were etched through a sequential photoelectrochemical oxidation and oxide-removing process to define the mesa region. The higher lateral wet-etching rate (similar to 3.4 mu m/h) of the InGaN active layer was observed to form a wider undercut structure which has 42.7% light output power enhancement compared to a conventional LED fabricated with the plasma dry etching process. The reverse current of a WME-LED was suppressed by avoiding plasma damage during the dry mesa etching process. (C) 2008 The Electrochemical Society.