Transferring Thin Film GaN LED Epi-Structure to the Cu Substrate by Chemical Lift-Off Technology

Abstract

In this paper, a patterned sacrificial layer structure comprised of 3 μm-wide SiO2 narrow strips and 3 μm spacing between strips fabricated on sapphire substrate was proposed. The structure was used not only to improve GaN epilayer quality, but also as a sacrificial layer structure. The GaN light emitting diodes (LEDs) covered by the Cu substrate was fabricated after the GaN epitaxy layer was grown on the sapphire by lateral epitaxial overgrowth. Chemical etching using hydrofluoric acid was conducted to remove the aforementioned SiO2 strips, and hence transform them into narrow tunnels. The GaN LEDs with the Cu substrate detached from the sapphire substrate after interface strain was increased, which demonstrates that n-side-up vertical GaN LEDs could be more easily obtained using chemical lift-off technology without laser damage compared with the laser lift-off technique.