Structure, Stress State and Piezoelectric Property of GaN Nanopyramid Arrays

GaN nanopyramid (NP) arrays have been fabricated by a convenient electrodeless photoelectrochemical etching method. Transmission electron microscopy measurement indicates that these NPs are composed of crystalline GaN surrounding a dislocation. High-resolution X-ray diffraction and the micro-Raman spectrum reveal a highly compressive stress relaxation in the NPs compared with compressed GaN subfilm. Additionally, negative piezoelectric current pluses are generated from the GaN NPs when the conductive atomic force microscope scans cross the arrays in the contact mode. The result demonstrates that the GaN NP arrays are a promising candidate for nanogenerators.