Controlled synthesis of GaN square shape nanorods: Their excellent electronic and optical properties for optoelectronics applications

High quality square shaped GaN nano-rods are successfully synthesized by a novel method of precursors pretreatment with aqueous NH3 via CVD method at 1300 °C. The pre-treatment effect significantly enhanced the conductivities, carrier concentrations and mobilities in GaN nanorods. GaN nanowires have also been synthesized at 1300 °C without treating precursors with aqueous NH3. Diameter of the nanorods and nanowires are measured in the range of 100-200 nm whereas length is in tenth of microns. Room temperature PL analysis of GaN nanowires displayed a high intensity near-band-edge emission at 370 nm with week blue emission. The GaN square nanorods exhibited the yellow band emission at 565 nm vanishing the weak blue emission along with the near-band-edge emission at 369 nm indicating their potential applications in optoelectronics. The carrier concentrations (Nd) are calculated to be 3.65–5.25 × 1016 cm−3 and 2.25∼5.88 × 1018 cm−3 for nanowires and nanorods respectively. The electron mobilities (μ) calculated for the GaN nanowires were in the range of 200∼300 cm2/Vs where as for the nanorods were 154∼625 cm2/Vs. The high quality GaN nanorods building blocks with high conductivities, career densities and mobilities will be a tremendous breakthrough in low voltage operating nano-devices.