Semi-polar (20-21) GaN microwire LED fabricated by laser lift-off and mechanical bending

Due to the lack of a suitable substrate, high-quality semi-polar GaN is usually obtained through overgrowth on a patterned substrate, which endows the epitaxial film with an approximately periodic trend in both surface morphology and defect distribution. This study utilizes these periodic properties in semi-polar (20-21) LED, to fabricated semi-polar (20-21) microwire LED with the processes of laser lift-off and mechanical bending. The obtained semi-polar (20-21) microwire has a length of hundred micrometers, with a residual stress of 207 MPa after separation. The microwire LED exhibits a stable blue emission under both optical pumping and electrical injection. A diode rectifying behavior was also demonstrated with a turn-on voltage of 2.2 V. This study provides a method to reach the GaN microwire, especially for the semi-polar and non-polar orientations.