The Study of Stress and Nitrogen Vacancies on GaN Nanowires by Raman Scattering and Current-Voltage Measurement

We report the Raman scattering and current-voltage (I-V) measurements of wurtzite GaN nanowires grown in different flow ratios of H(2)/(NH(3)+H(2)) ambient by chemical vapor deposition. In Raman measurements, the variation of the E(2)(high) peak position revealed that the nanowires exhibit tensile stress resulting from hydrogen relaxation. Compared with nanowires with a smooth surface, the nanowires with a rough surface had a higher intensity ratio of A(1)(LO)/E(2), where LO is longitudinal optical. For I-V measurement, the decreasing of resistance and the increasing of ideality factor for different nanowires revealed that the electron tunneling behavior between the metal-semiconductor interface was the dominate mechanism. This result was caused by the formation of nitrogen vacancies in GaN nanowires.