Structural changes in sol-gel films with photo-irradiation were investigated using zinc oxide (ZnO) derived from zinc acetate. The exposure of the films to an ultraviolet lamp induced hexagonal ZnO crystals in a relatively dense amorphous structure. On the other hand, the formation of zinc metal was found in a porous gel film. The photo-induced crystallization and reduction are ascribed to the electronic excitation in the metastable non-crystalline states.

Crystallization and Reduction of Sol-Gel-Derived Zinc Oxide Films by Irradiation with Ultraviolet Lamp

Characterization of amorphous and nanocrystalline carbon films

During the last years, ZnO thin films have been studied extensively due to their potential applications in e.g. piezoelectric and optoelectronic devices or photovoltaic cells. Ordered c-axis orientation of ZnO crystallites is desirable for applications where crystallographic anisotropy is a prerequisite such as for short-wavelength semiconductor diode lasers (SDLs), and piezoelectric surface acoustic wave or acousto-optic devices. Many works were dedicated to c-axis oriented ZnO thin films elaboration and the study of their properties, including physical and chemical methods. For instance, sol–gel processes are particularly well adapted to produce ZnO films in a simple, low-cost and highly controlled way. This review summarizes the main chemical routes used in the sol–gel synthesis of undoped ZnO thin films and highlights the chemical and physical parameters influencing their structural properties. In this process, the ZnO films synthesis includes three principal steps: (i) solution preparation, (ii) coating and (iii) heat treatment. For the first step, the particle formation is discussed including nucleation and growth, particle size, morphology and colloids stability. These three steps involve several parameters such as: (i) nature and concentration of precursor, solvent and additive, and solution aging time, for the chemical system, (ii) coating method, thickness and substrate for the coating step, and (iii) pre-and post-heat treatment for the last step. The influence of these steps and synthesis parameters on ZnO thin films orientation is discussed.

Sol–gel-deposited ZnO thin films: A review

Novel group 14 nitrides

Structure and electrical conductivity of nitrogen-doped carbon nanofibers

A novel approach to prepare zinc oxide films: excimer laser irradiation of sol–gel derived precursor films

Visible Raman spectroscopy excited at 532 nm was used to characterize the carbon bonding in tetrahedral amorphous carbon (ta-C) films. The vibrational modes of the sp3 bonding in ta-C films were revealed directly. An additional Raman band occurring below 1350 cm−1 was observed. It consisted of two features centered on ∼1270 and ∼1170 cm−1, which were associated with sp3 bond stretching. The observed sp3 related Raman spectrum approached the vibrational density of states of amorphous diamond.

Observation of sp3 bonding in tetrahedral amorphous carbon using visible Raman spectroscopy

Carbon nitride films were deposited by pulsed Nd:yttrium–aluminum–garnet laser ablation of graphite with assistance of low energy nitrogen-ion-beam bombardment. The nitrogen to carbon (N/C) atomic ratio, surface morphology, bonding state, and microstructure of the deposited carbon nitride films were characterized by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy, atomic force microscopy (AFM), and x-ray diffraction. The influence of laser fluence on the synthesis of carbon nitride films was investigated. The N/C atomic ratio of the carbon nitride films can reach the maximum at the highest laser fluence. XPS and FTIR analyses indicated that the bonding state between the carbon and nitrogen in the deposited films was significantly influenced by the laser fluence during deposition. The carbon–nitrogen bonding of C–N and C=N were observed in the films. In addition, α and β C3N4 phases were found to coexist in the carbon nitride films with relat...

Structural and bonding properties of carbon nitride films synthesized by low energy nitrogen-ion-beam-assisted pulsed laser deposition with different laser fluences

Carbon nitride thin films were deposited by pulsed laser deposition with nitrogen ion beam assistance at a substrate temperature varying from room temperature to 800 °C. The effect of the substrate temperature on the nitrogen content, surface morphology, structure, and electrical property of the carbon nitride films was investigated. The deposited films were characterized by atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and four-probe resistance. The nitrogen content of the deposited films reached its maximum value of 25% at a substrate temperature of 400 °C. AFM images revealed that an island structure occurred and developed on the surface of the films deposited at the high substrate temperature. FTIR and XPS spectra showed the existence of sp3C–N and sp2C=N bonds in the deposited films. The deposited carbon nitride films had an amorphous structure with two carbon nitride phases inclusions, which had a stoichiome...

J. Sakakibara

Papers

A novel approach to prepare zinc oxide films: excimer laser irradiation of sol–gel derived precursor films

Observation of sp3 bonding in tetrahedral amorphous carbon using visible Raman spectroscopy

Structural and bonding properties of carbon nitride films synthesized by low energy nitrogen-ion-beam-assisted pulsed laser deposition with different laser fluences

Effect of temperature on carbon nitride films synthesized by ion-beam-assisted pulsed laser deposition

Growth of nano-crystalline diamond by pulsed laser deposition in oxygen atmosphere