Field Emission Properties of Hybrid Carbon Nanotube−ZnO Nanoparticles

ZnO nanoparticles are uniformly coated on the walls of carbon nanotubes (CNTs) via a straightforward process, and the particle size and interparticle distance can be controlled by coating time. The appropriate amount of coated nanoparticles effectively reduces the formation of various structural defects induced by oxygen or hydrogen atoms on the walls of CNTs, which can be evaluated through a decrease in the intensity ratio of disorder graphitic band (D peak) over graphitic C−C stretching band (G peak) in the Raman spectrum. An overincrease in coating time simultaneously causes an increase in interstitial zinc and oxygen vacancies in ZnO. The high local electric field around the ZnO particle on the walls of CNTs can increase the tunneling probability at CNTs−ZnO heterojunction, significantly enhancing the field emission property for CNTs.