Centimeter-long III-Nitride nanowires and continuous-wave pumped lasing enabled by graphically epitaxial lift-off

Abstract

It remains a big challenge to elongate one-dimensional (1D) semiconductor nanowires (NWs), which can be attractive platforms for miniaturizing and/or integrating macroscopic devices, into centimeter-scale length. Herein, we report the innovative preparation of single-crystalline III-nitride NWs, with unprecedented length above 2 cm and the aspect ratio above 6000, by graphically epitaxial lifting-off (GELO) the epitaxial films on sapphire. The proposed GELO technology involves isotropic dry etching and selectively electrochemical (EC) etching. Reaction kinetics study of the EC etching indicate that two-steps processes are included, which is, to our best knowledge, firstly revealed and experimentally confirmed. Centimeter-long freestanding NWs, with predesigned structure of homogeneous GaN, p-GaN/(InGaN/GaN) 6 quantum-wells/n-GaN (simply InGaN/GaN QWs) and AlGaN/AlN/GaN heterostructure, are successfully obtained and exhibit superior morphological uniformity and robust flexibility. Optical properties of the released InGaN/GaN QW-NWs were well optimized owing to the relieved intrinsic strain. Random lasing behavior was unexpectedly observed by continuous-wave excitation of the individual InGaN/GaN QW-NW, with a low threshold of 232 kW•cm -2 . This work represents a low-cost and economic approach to yield structure-engineerable super-long III-nitride NWs, which would promote the development and integration of optoelectronic nanodevices. • Centimeter-long III-nitride NWs with engineerable structure are prepared by the graphically epitaxial lift-off method. • Reaction kinetics study of EC etching indicate that two-steps processes are included, which is experimentally confirmed. • Continuous-wave pumped random lasing of the individual InGaN/GaN QW-NW was observed with a low threshold of 232 kW•cm -2 .