Vertical Light-Emitting Diode Fabrication by Controlled Spalling

A fracture-based layer transfer technique referred to as controlled spalling was used to separate a conventional InGaN/GaN multiple quantum well light-emitting diode (LED) structure from a 50 mm sapphire wafer enabling the formation of vertical spalled LEDs (SLEDs). A 25-mu m-thick tensile Ni layer was electrodeposited on the surface of the wafer, followed by the application of a polyimide tape layer. By mechanically guiding the tape layer, a 3-mu m-thick layer of the LED epitaxy was removed. Transmission electron microscopy imaging indicated that spalling preserved the quality of the epitaxial layers, and electroluminescence verifies the operation of the SLED. (C) 2013 The Japan Society of Applied Physics