Ultrafast Laser Lift-off of Semipolar GaN-based LEDs on Sapphire Substrates
The poor substrate conductivity and thermal properties have been a big challenge for GaN-based LEDs grown on sapphire substrates.Utilizing laser lift-off technology to transfer GaN-based LEDs from sapphire substrates to alternative substrates has emerged as an effective solution.This paper employed ultrafast picosecond laser to de-tach semi-polar GaN-based LEDs overgrown on patterned sapphire substrates and successfully transfered them to Si substrates,forming vertical structure LED devices.SEM measurements revealed that at a laser energy density of 1.3 J/cm²,efficient decomposition of the sapphire and GaN interface occurred,minimizing adverse effects on the devic-es.Raman spectroscopy results demonstrated effective stress release in the GaN layer,in which the residual stress decreases from 1.42 GPa to 0.29 GPa.I-V measurements of the fabricated vertical structure LEDs showed an in-crease in forward current from 0.164 mA to 0.759 mA at 5 V voltage,along with an enhancement in photolumines-cence and electroluminescence performances.This study presents experimental research on ultrafast laser lift-off of semi-polar GaN-based LEDs on sapphire substrates,providing support for the development of low-damage,high-effi-ciency transfer technologies.It holds promise in accelerating the advancement and application of semi-polar GaN-based LEDs.
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