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-μm-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-μm-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.