Theoretical investigation of electronic structure and field emission properties of carbon nanotube–ZnO nanocontacts Original Research Article

A density functional theory study is performed to understand electronic structures and field emission properties of carbon nanotube–ZnO nanocontacts. The carbon nanotube–ZnO nanocontacts have high energetic stabilities and small energy gaps. The energy gaps of the nanocontacts exhibit an oscillatory behavior as a function of the length of carbon nanotubes. The ionization potentials of all carbon nanotube–ZnO nanocontacts are smaller than 7.155 eV of the ZnO nanocage. The ionization potentials of carbon nanotube–ZnO nanocontacts with more 2 carbon layers exhibit odd–even oscillation in the absence and presence of an electric field. The carbon nanotube–ZnO nanocontact with 4 carbon layers has a smallest ionization potential of 3.625 eV under 0.2 eV/Å external electric field. These results indicate that the field-emission properties of simplex ZnO and carbon nanotube materials can be enhanced significantly by the formation of carbon nanotube–ZnO nanocontacts.