To realize the room-temperature ferromagnetism (RTFM) in diluted magnetic semiconductors (DMS), we
prepared a series of Cobalt-doped ZnO thin films using pulsed laser deposition (PLD) at deposition temperatures 500°C
under oxygen pressure from 2.5×10-4 Pa to 15 Pa. To elucidate the physical origin of RTFM, Co 2p spectra of
cobalt-doped ZnO thin films was measured by X-ray photoelectron spectroscopy (XPS). The magnetic properties of
films were measured by an alternating gradient magnetometer (AGM), and the electrical properties were detected by a
Hall Effect instrument using the Van der Pauw method. XPS analysis shows that the Co2+ exists and Co clusters and
elemental content change greatly in samples under various deposition oxygen pressures. Not only the valence state and
elemental content but also the electrical and magnetic properties were changed. In the case of oxygen pressure 10 Pa, an
improvement of saturation magnetic moment about one order of magnitude over other oxygen pressure experiments, and
the film exhibits ferromagnetism with a curie temperature above room temperature. It was found that the value of carrier
concentration in the Co-doped ZnO film under oxygen pressure 10Pa increases about one order of magnitude than the
values of other samples under different oxygen pressure. Combining XPS with AGM measurements, we found that the
ferromagnetic signals in cobalt-doped ZnO thin film deposited at 500 °C under oxygen pressure 10 Pa only appear with
the detectable Co2+ spectra from incompletely oxidized Co metal or Co cluster. So oxygen pressure 10 Pa can be
thought the best condition to obtain room-temperature dilute magnetic semiconductor about cobalt-doped ZnO thin
films.
Transparent thin films are manufactured by PLD (pulsed laser deposition) in different oxygen pressure. The various
property of samples is measured by Atomic Force Microscope (AFM), X-ray diffraction (XRD) and optical transmission
spectrum. All samples retain the original structure in wurtzite lattice by XRD, there is not being of metallic cobalt or
other impurity phase with the limit detection. The surface morphology of the films observes the smoother than that in
undoped ZnO thin film. The transparency of thin films has altered greatly with the different oxygen pressure or not by
PLD, which is shown that the oxygen pressure has impacted on the transparency of the film and surface morphology.
And UV-visible spectra fully have been demonstrated the presence of Co2+ to substitute for Zn2+ in the films with the
different oxygen pressure.
In this paper, the high temperature solid state reaction method was applied to the preparation of SrTiO3 ceramic target.
The phase of the target has been researched in experiment by X-ray diffraction (XRD). We found that solid state reaction
has achieved completely. Then SrTiO3 thin films on MgO (100) substrate were manufactured by PLD using the
triple-frequency harmonics of pulsed laser Nd: YAG. The thickness of the SrTiO3 thin films was measured using a stylus
profiler. Their microstructure and surface morphology were analyzed using X-ray diffraction (XRD) and atomic force
microscopy (AFM). Their optical character was characterized using optical transmission spectrum. Additionally, X-ray
photoelectron spectroscopy (XPS) spectra were used to characterize the surface chemical composition of the
SrTiO3 thin film. In accordance with the above text result, the relation between the substrate temperature and the SrTiO3
thin films' the structure and character was analyzed and discussed. With increasing temperature of the substrate, film
grain size gradually increased and then smaller. The optimized substrate temperature was found to be 700 °C at which the
STO films' structure could uniformly dense. The STO films present a low optical absorption in the 400~1000nm
wavelength range, and the substrate temperature is not the main reason for the impact of the optical absorption. The
optical band gap energy was found to be about 3.5 ~ 4.0eV for the STO thin film. The valences of the three elements (Sr,
Ti, and O) in the STO film prepared by PLD are 2+, 4+ and 2-, respectively.
In this paper, the effects of substrate temperature during film growth at relative high temperature have been reported. The
IGZO thin films were fabricated by means of pulse laser deposition (PLD) with the InGaZnO (In2O3: Ga2O3: ZnO=1: 1:
8 mol %) target. The substrate temperature altered from room temperature (RT) to 800 °C. The product thin films were
characterized rigorously by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-VIS spectrometer, Halleffect
investigation and X-ray photoelectron spectroscopy (XPS). The IGZO films was with smooth surface, high
transmission in the visible spectral range (about 75-92 %), carrier mobility > 8.0 cm2/(V·s) and carrier concentration at
about 1018 cm-3. Finally, the character changes influenced by temperature were obtained from analysis results. This task
may benefit to a flat panel display in the process of thin film transistors(TFT) fabrications and improvements.
All-fiber coupler is a kind of widely utilized passive instrument in optical-fiber communication, optical-fiber sensor,
optical-fiber measurement and signal processing, the application of all-fiber couplers are being used in different research
fields. In this paper, the primary investigation is focused on the optical coupling theory, and derived from the theory of
fused and tapered coupler how to make light apart with the equation of coupled wave. The relative formula between the
ratio of power coupling and length of drawing has obtained with simulation using the standard fused and tapered coupler,
at the same time the losses and the power distribution of fused and tapered all-fiber coupler are analyzed and computed
by simulation. The single-window 1×2 for 1310nm and 1550nm couplers have constructed in experiment, respectively.
The couplers' optical parameters of output spectrum and power in theoretical analysis are accorded with the testing
standard in experiment.
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