Chemical lift-off process for nitride LEDs from an Eco-GaN template using an AlN/strip-patterned-SiO2 sacrificial layer

Abstract

In this research, a nitride light-emitting diode (LED) fabricated on an electroplated Cu substrate can be removed from a GaN/sapphire (Eco-GaN) template by conducting the chemical lift-off (CLO) process using an AlN/strip-patterned-SiO2 intermediate sacrificial layer. The regrowth GaN epilayer deposited on AlN/patterned SiO2/Eco-GaN can achieve a high crystal quality via the epitaxial lateral overgrowth process. To etch the patterned SiO2 and AlN layers, the HF and 80 degrees C-KOH solutions were used, respectively. Due to the use of low-temperature KOH solution, the GaN epilayer would suffer less damage during the CLO process, improving the reuse feasibility for the Eco-GaN template. Moreover, when the etching treatment was used for the AlN layer, a highly lateral etching rate of 0.5mmh(-1) was achieved. Compared to the conventional LED, the vertical-type LED/Cu substrate had a higher output power of 212mW (at 350mA). Based on our estimation, the output power of LED prepared on Cu substrate had an 86% improvement in comparison to that of conventional LED. Obviously, the good optoelectronic performance of the LED/Cu device can be obtained after performing the CLO process. Furthermore, the separated Eco-GaN template has high potential for reuse applications, indicating that this technique is helpful to the cost-effective LED fabrication.