Effect of Surface Treatment on the Performance of Vertical-Structure GaN-Based High-Power Light-Emitting Diodes with Electroplated Metallic Substrates

Large-area (0.6 × 0.6 and 1 × 1 mm 2 ) highly-efficient GaN-based light-emitting diodes (LEDs) with a vertical-conducting structure (VM-LEDs), using a patterned laser lift-off technique and a Ni electroplating process as well as a surface treatment of the top n-GaN epilayer by plasma and chemical etching, were successfully fabricated and investigated. Compared to regular LEDs of the same size, both the forward voltage drop and the light output power ( L op ) of the VM-LED were substantially improved. With inductively coupled plasma (ICP) etching followed by an additional KOH etching and an HF/HCl treatment on the n-GaN layer, an increase in L op by 227% (195%) at 350 (800) mA has been achieved for the (1 × 1 mm 2 )-sized VM-LEDs.