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High-quality (1 1 0) Fe films with thickness of 200 nm were grown on Al 2 O 3 (0 0 0 6) substrates by low-pressure metal organic chemical vapor deposition (LP-MOCVD). The effects of residual carbon and post-annealing treatment on magnetic properties of Fe films were studied. X-ray photoelectron spectroscopy (XPS) measurements revealed that almost all the interstitial carbon atoms in Fe films can be removed by annealing at temperature of 600 °C. Vibrating sample magnetometer (VSM) showed that the in-plane (out-of-plane) coercivity of the film annealed at 600 °C is clearly larger (smaller) than that of as-grown one, which can be assigned to the tensile stress relaxation due to the removal of carbon. As the annealing temperature increased from 600 to 750 °C, the in-plane coercivity decreased while the out-of-plane coercivity increased. Meanwhile, the in-plane remanence ratios increased rapidly with the increase of annealing temperature, but the out-of-plane remanence ratios changed slightly. The origin of the changes of magnetic properties with annealing temperatures was discussed.

Nonionic polymer poly (vinylpyrrolidone) (PVP) was firstly mixed into oxygenated zinc chloride electrolyte to modulate the crystal growth and morphology of ZnO from electrodeposition. Arrays of ZnO hexagonal prisms with well-defined (0 0 0 1) end facets and { 1 0 1 ¯ 0 } side facets were grown perpendicularly onto p-type Si substrates using the simple and economic route. It was observed that the concentration of PVP played an important role in the final morphology and size of ZnO crystals. The optical studies indicated that the addition of PVT not only influenced crystal growth habit but also improved the optical properties of ZnO.

The morphology, structure and photoluminescence properties of ZnO nanostructures synthesized from different zinc precursors by a vapor transport process were investigated. The zinc precursors involved pure zinc powder, zinc powder mixed with graphite and zinc powder mixed with carbon nanotubes. The products were characterized by XRD, FESEM, TEM, Raman and PL techniques. The results indicated that the zinc precursors have a strong effect on the morphology and structural properties of the ZnO nanostructures. For the pure zinc, zinc mixed with graphite and zinc mixed with carbon nanotube, uniform tetrapod-, chrysanthemum- and needle-like morphologies are obtained, respectively. Photoluminescence measurements show that all the products have a strong near-band-edge UV emission accompanied by weak visible emissions. The relatively stronger green-light emission from the tetrapods implies that more defects exist in the tetrapods. A peak at 445 nm is found in the spectrum of the tetrapod-like nanostructures, which may be caused by oxygen-depletion interface traps. Furthermore, products synthesized at 600 °C demonstrate better photoluminescence properties than those synthesized at 450 °C.

Comprehensive Raman and photoluminescence (PL) results on ZnO nanocrystals are presented in this work. The ZnO nanocrystals were prepared by plasma-assisted electron beam evaporation of metallic Zn films on GaInPAs films, which were previously grown on InP substrates by MOCVD, then a low-temperature annealing process was conducted on the as-deposited Zn films. Raman results show the presence of a surface phonon (SP) mode, which reveals that nanocrystals are embedded in a compound matrix. Seven longitudinal optical-phonons (LOs) accompanied by SPs are observed in the resonant Raman spectrum for our ZnO nanocrystals at 80 K, which is probable due to a strong surface enhanced Raman scattering (SERS) effect and quantum confinement effect. Room temperature PL spectra show a single broad UV peak at around 3.45 eV with sharp Raman lines superimposed upon it, indicating a large quantum confinement effect in the ZnO nanocrystals due to their small dimensions. PL spectra measured at different temperatures show an anomalous dependence of the PL intensity with variation in temperature, which is analyzed on the basis of John-Singh's model. The total PL intensity is governed by the combination of radiative and non-radiative processes.

High quality ZnO thin films have been grown on Si (1 0 0) substrates with MgO buffer layers. An electron beam evaporation technique was used to grow MgO buffer layer on Si substrates followed by a magnetron sputtering process to deposit Zn films on the MgO-buffered Si substrates, next, a two-step annealing process was employed to oxidize the Zn films to form ZnO. The effects of the annealing temperature on the photoluminescence (PL) and orientation of ZnO nanocrystalline thin films were studied. For ZnO films annealed between 400°C and 700°C in an O 2 ambient, the quality of the ZnO films was improved with increasing annealing temperature. However, as the annealing temperature was increased to over 800°C, the ZnO film underwent a phase transformation from ZnO to a Mg x Zn 1− x O alloy, where the x value in the alloy increased with increasing annealing temperature. The Mg x Zn 1− x O alloy films were characterized by X-ray diffraction (XRD), photoluminescence (PL) and reflection spectra. XRD results show that the Mg x Zn 1− x O alloy films maintain the hexagonal structure with a lattice constant close to that of ZnO. In films with Mg incorporation, intense ultraviolet band edge photoluminescence was observed at room temperature. The photoluminescence (PL) spectra show that Mg x Zn 1− x O alloy has a wide band gap with a large exciton binding energy of 53 meV. The band gap of the Mg x Zn 1− x O alloy shifts to higher energy with increasing annealing temperature. The blue-shift of the fundamental band gap of the alloy annealed at 1000°C is estimated to be ∼300 meV.

Rare-earth (RE) Tb3+ ion doped ZnO and Mg0.15Zn0.85O thin films were successfully fabricated by the sol–gel deposition method. The Tb3+ ion was substituted for the Zn2+ ion in the host material, as revealed by X-ray diffraction and optical absorption spectra. The cathodoluminescence properties of the doped samples were also studied. The RE3+ luminescence mechanism is discussed.

A series of MgxZn1−xO thin films were successfully fabricated by the sol–gel method on n-type Si (0 0 1) and quartz substrates. The structural and optical properties were studied using XRD and the transmittance spectrum. The Mg0.05Zn0.95O and Mg0.15Zn0.85O alloys with wurtzite structure show high thermal stability up to 1000°C. However, when x is 0.36, phase separation will occur at 800°C. The optical band gap of MgxZn1−xO alloys (0⩽x⩽0.36) ranges from 3.4 to 3.93 eV.