Bending strain effects on the optical and optoelectric properties of GaN nanowires

Elastic strain has been an important method to regulate the electronic structures and physical properties of nanoscale semiconductors due to the promising potentials in improving the performance of their optoelectronic devices. Here, we report the investigation of bending strain effects on the optical and optoelectric properties of individual gallium nitride (GaN) nanowires (NWs). By charactering the near-band emission spectrum of individual GaN NWs at different bending strains with low temperature cathodoluminescence (CL), we reveal that the near-band emission splits into two peaks, where the low energy peak displays a linear redshift with increasing the bending strain while the high energy one shows a slight blueshift. Further localized ultraviolet (UV) photoresponse measurements illustrate that the photoresponse of the GaN NWs shows a linear increase with the bending train, and the maximum enhancement is more than two orders of magnitude. The experimental observations are well interpreted by theoretical calculations on the strain modulation on the electronic band structure of GaN combined with analysis of carrier dynamics and optical waveguide effect in the bending strain field. Our results not only shed light on the bending strain effects on the optical and optoelectric properties of semiconductors, but also hold potential to help the future design of high performance nano-optoelectric devices.