Vacuum electron field emission from SnO₂ nanowhiskers annealed in N₂ and O₂ atmospheres

The field emission properties of SnO₂ nanowhiskers were observed to change after annealing under O₂ and N₂. The electron current increased significantly from the sample annealed in N₂ and the threshold field decreased from 3.17 V/μm of the as-grown sample to 2.59 V/μm of the annealed sample. The mechanism of the field emission enhancement was explored using Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy (XPS). The results reveal that after annealing in N₂, the amount of Sn-O bonds decreased and N atoms were introduced onto the surface. The binding energies of Sn 3d and O 1s determined by high resolution XPS analysis show a shift of 0.55 and 0.47 eV, respectively, toward the high energy side. This shows that the electron emission enhancement arises from a decrease in the work function. The changes in the field emission effect from the sample annealed in O₂ are different and a possible mechanism is also proposed. © 2006 American Institute of Physics.