Photocurrent analysis of In–Ga–Zn–O (IGZO) film

We investigated the electrical properties of the In–Ga–Zn–O (IGZO) film under light illumination. We measured the photoconductivity of a-IGZO thin film under light illumination with various intensities. We extracted the photoexcitation activation energy and dark relaxation activation energy through extended stretched exponential analysis. Dark relaxation characteristics, which are related to the recombination process, show longer time constant, τ, larger effective activation energy Eac, and lower stretching exponent, β, with wider activation energy bandwidth, Δac, than those corresponding to those of photoexcitation. These indicate that recombination takes place more slowly and through more deeply bound activation processes with the broader distribution of activation energies than those corresponding to photogeneration process. The wider distribution for the dark relaxation energy for the higher light intensity suggests that the metastable state distribution is related to the distribution of the oxygen vacancy state, Vo. We also concluded that the usage of the right value of the attempt-to-escape frequency is important to estimate the exact value of Eac.

A series of unexpected ferromagnetic behaviors based on the surface-vacancy state: an insight into NiO nanoparticles with a core–shell structure

We propose that the observed anomalous ferromagnetic behavior of NiO nanoparticles is due to the formation of a ferromagnetic particle shell that is oxygen-vacancy related.

Multicharged Xei+ ions formed after de-excitation of inner-shell vacancies in Xe atom

Multicharged Xe ions following de-excitation of K-, L1-, L2,3-, M1-, M2,3-, and M4,5-subshell vacancies are calculated using a Monte-Carlo algorithm to simulate the vacancy cascade development. Fluorescence yield (radiative) and Auger and Coster–Kronig yields (nonradiative) are evaluated. The decay of the K hole state through radiative transitions is found to be more probable than through nonradiative transitions in the first step of de-excitation. On the other hand, the decay of L and M vacancies through nonradiative transitions are more probable. Ions, mainly produced from Xe in the K-shell vacancy state, are found to be Xe7+, Xe8+, Xe9+, and Xe10+. The charged Xe8+ ions predominate in the charge state distributions. The main product from the L1-shell ionization is found to be Xe8+ and Xe9+ ions, while the Xe8+ ions predominate at the L2,3 hole states. The charged Xe6+, Xe7+, and Xe8+ ions come mainly from 3s1/2 and 3p1/2,3/2 ionization, while Xe in 3d3/2,5/2 hole states becomes mainly Xe4+ and Xe5+ ions. The present results are found to agree well with the experimental data.PACS No.: 32.40.Hd