Surface plasmon resonance of gold and silver nanoparticle (NP) layers is investigated by the experiment as well as simulations. Although the good agreement was found for gold NP film, a significant mismatch in the resonance energy for silver NP film was observed. The deviation was assigned to the presence of silver oxide (Ag2O) in silver NPs. As an alternative to the NP size-dependent Drude model, the analysis based on effective medium approximation for refractive index of Ag-Ag2O material system is carried out and compared with the core-shell model. Both Mie's model and numerical simulation results illustrate shift of the surface plasmon resonance due to silver NP surface oxidation.
Aluminum -doped ZnO thin films (ZnO:Al) and Al -N co-doped (ZnO:Al:N) thin films were prepared by RF diode sputtering from a ceramic target (ZnO+2 wt. % Al 2 O 3 ) in Ar and Ar/25÷75 %N 2 atmosphere. The ZnO:Al films exhibited n-type conduction with a minimum resistivity (2x10 -3 cm), a high visible transmittance (> 82 %, including Corning glass substrate) and an optical band gap E g ~ 3.3 eV. The p-type doping efficiency of the nitrogen was investigated as a function of the nitrogen content in the sputtering gas. The ZnO:Al:N thin films with a p-type conduction were obtained for 75 % N 2 in the Ar/N 2 gas. Their resistivity and the hole concentration were 21 cm and 7.8x10 17 cm -3 respectively. The micro -Raman scattering measurements revealed N -related local vibrational modes (LVMs) at 276.44 cm -1 and 518.47 cm -1 in the spectra of the films grown with nitrogen and proved that the p-type conduction was a result of the nitrogen incorporation and formation of N O acceptors. The average transmittance (74÷86 %, including Corning glass substrate) and E g (3.22 -3.10 eV) depended on the N 2 content in the sputtering gas. The p-/n-type ZnO thin films were utilized for preparing p-n heterojunction structures on (100) n-type and (111) p-type silicon substrates. Rectification was clearly observed for both structures.
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