Size-dependent electronic structures of ZnO nanowires

Abstract

ZnO nanowires with a diameter distribution from 20 to 100 nm were fabricated by a simple thermal evaporation process. Two different types of nanowire (circular versus hexagonal cross section) were obtained by controlling the growth conditions. The size-dependent electronic structures of both types of samples were investigated using valence electron energy-loss spectroscopy. Both the common features (surface plasmon, bulk plasmon width) and the differences (O 2s interband transition, bulk plasmon energy) between the two types of samples are discussed. The experimental results strongly suggest that ZnO nanowires with hexagonal cross section and low-index terminating surfaces are of high electronic quality, even at 20 nm diameter, and can thus serve as effective building blocks for optoelectronic nanodevices.

Effect of growth temperature on structural and electronic properties of ZnO thin films

“…Several other common peaks at 9.5, 13.5, and 21.8 eV are identified respectively as interband transition from the O 2p, the Zn 3d, and the O 2s states in the valence band to occupied states in the conduction band. These peaks position agree well with those of nano-wire ZnO, indicating that the general electronic structure of the ZnO thin films are in nano dimension [12,13].…”

Characterization of wurtzite ZnO using valence electron energy loss spectroscopy

“…4 As such, also the ZnO optical properties have been investigated by EELS. [5][6][7][8][9][10] However, the underlying dielectric function has not been applied to explain the spectral features observed in these studies. 5,10 Moreover, the dependence of the energy loss features of ZnO on material size and geometry has been explored by examining nanowires of different sizes under TEM diffraction mode.…”

Quantum size effect of valence band plasmon energies in Si and SnOx nanoparticles

“…[1][2][3] Volume plasmons are long-wavelength, collective excitations of charge carriers. 3 Only a few studies exist on confinement effects of valence band plasmons in dielectrics [8][9][10][11][12][13][14][15] although changes of the plasmon energy are of practical relevance for adjustable optical edge filters in the ultraviolet range. While this relationship is usually well fulfilled for dielectrics, it is violated in transition metals due to mixing of d-and s-electron states.…”