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We report a simple and continuous spray-drying method to synthesize high-purity epsilon iron oxide (ε-Fe2O3). The strategy enables ferromagnetic resonance tuning, making it potentially usable in millimeter-wave absorbers.

ZnS thin films were deposited on glass substrates by radio frequency (RF) magnetron sputtering. The sputtering power was varied from 60 to 120 W in 20 W increments. The effects of the sputtering powers on the structural and optical properties of the ZnS thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy. XRD showed that the films were polycrystalline with a cubic structure and preferential orientation along (111) the directions. ZnS thin films deposited at higher sputtering power showed better crystallinity than that of the films deposited at lower sputtering power. FESEM images of the surface morphology clearly show that a high sputtering power enhanced the particle size and nucleation of the ZnS thin films. The optical band gap was reduced from 3.96 to 3.47 eV and the optical transmission improved with the sputtering power from 60 to 120 W.

Copper sulfide (CuS) thin films were deposited on a glass substrate at room temperature using the radio-frequency (RF) magnetron-sputtering method at RF powers in the range of 40−100 W, and the structural and optical properties of the CuS thin film were investigated. The CuS thin films fabricated at varying deposition powers all exhibited hexagonal crystalline structures and preferred growth orientation of the (110) plane. Raman spectra revealed a primary sharp and intense peak at the 474 cm−1 frequency, and a relatively wide peak was found at 265 cm−1 frequency. In the CuS thin film deposited at an RF power of 40 W, relatively small dense particles with small void spacing formed a smooth thin-film surface. As the power increased, it was observed that grain size and grain-boundary spacing increased in order. The binding energy peaks of Cu 2p3/2 and Cu 2p1/2 were observed at 932.1 and 952.0 eV, respectively. Regardless of deposition power, the difference in the Cu2+ state binding energies for all the CuS thin films was equivalent at 19.9 eV. We observed the binding energy peaks of S 2p3/2 and S 2p1/2 corresponding to the S2− state at 162.2 and 163.2 eV, respectively. The transmittance and band-gap energy in the visible spectral range showed decreasing trends as deposition power increased. For the CuS/tin sulfide (SnS) absorber-layer-based solar cell (glass/Mo/absorber(CuS/SnS)/cadmium sulfide (CdS)/intrinsic zinc oxide (i-ZnO)/indium tin oxide (ITO)/aluminum (Al)) with a stacked structure of SnS thin films on top of the CuS layer deposited at 100 W RF power, an open-circuit voltage (Voc) of 115 mA, short circuit current density (Jsc) of 9.81 mA/cm2, fill factor (FF) of 35%, and highest power conversion efficiency (PCE) of 0.39% were recorded.

Tin sulfide (SnS) thin films were deposited with a single SnS target by radio frequency magnetron sputtering while varying the working pressure (0.6 Pa to 2.6 Pa), and the structural, chemical, electrical and optical properties of the SnS thin films were investigated. X-ray diffraction results showed that all the SnS thin films had a (111) plane preferred growth orientation, and X-ray photoelectron spectroscopy verified that a SnS thin film was grown with an orthorhombic crystal structure that had, a binding energy of 324.5 eV. Owing to the long wavelength shift in the transmittance spectrum, the optical band gap decreased from 1.56 eV to 1.47 eV. The SnS-based conventionally structured solar cell (Al/ITO/i-ZnO/CdS/SnS/Mo/SLG), which was prepared with a SnS absorption layer and deposited at a working pressure of 2.0 Pa, achieved the highest power conversion efficiency of 0.58%. This result shows its high efficiency compared to those with a conventional structure in other reports.

Two types of alumina dispersion-strengthened Cu alloy were fabricated by surface oxidation reaction by the aging of Cu–0.31 wt%Al and Cu–0.28 wt%Al–0.07 wt%Ti alloys in air. After heat treatment at 980 °C for 1 h in air, a 0.2 mm-thick alumina-dispersed plate could be prepared. The alumina-dispersed alloy with Ti addition showed higher values of conductivity, hardness, and tensile strength than the alloy without Ti.

In this study, we investigated the structural and optical properties of indium sulfide (In2S3) thin films as a substitute for the CdS buffer layer in Cu(In,Ga)Se2 (CIGS) solar cells. The In2S3 films were deposited on glass substrates using radio frequency (RF) magnetron sputtering. The sputtering power was changed from 60 to 120 W in 20 W increments. The effects of sputtering power on the crystallinity, surface morphology, and optical properties of the films were characterized with X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), and UV-visible spectrophotometry. The XRD analyses indicated that the films were polycrystalline β-In2S3 structures with two preferred orientations along the (103) and (206) directions. The AFM images revealed that the films had nanosized grains and that the size increased from 7 nm for the samples prepared at 60 W to 13 nm for those prepared at 120 W. The optical band gap of the samples was found to vary between 2.88 and 2.43 eV.

A one-step route was developed to fabricate (CIGS) thin films by radio frequency (RF) magnetron sputtering from a single quaternary target. The effects of the substrate temperatures on the structural and electrical properties of the CIGS layers were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and Hall effect measurements. All the deposited films showed a preferential orientation along the (112) direction. The films deposited at and revealed that chalcopyrite main (112) peak and weak prominent peaks of (220)/(204) and (312)/(116), indicating polycrystalline structures. The element ratio of the deposited film at were almost the same as the near-optimum value. The carrier concentration of the films decreased with increasing substrate temperatures.

CdS thin films were prepared by radio frequency magnetron sputtering with different sputtering power. The effects of sputtering power on crystallinity, surface morphology and optical properties of the films were characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible transmission spectra. The XRD measurement revealed that CdS films were polycrystalline and retained the mixed structure of hexagonal wurtzite and cubic phase. As the power increased, the H(002)/C(111) peak was more intense and sharper. This indicates that the CdS films are grown with the preferred orientation of the H(002)/C(111) plane at higher power, resulting in improvement in the film crystallinity. The morphology of all films was found to be continuous and dense. An increase in the power from 60 to 120 W, the optical band gap decreased from 3.44 to 2.42 eV.

NiO-doped p -type AZO (Al/Zn = 1.5 at.%) films were synthesized on glass substrates using a simple and low cost sol–gel solution method. p -type conductivity could be achieved by annealing the NiO:AZO films in N 2 /H 2 forming gas at 550 °C. The real Al/Zn and Ni/Zn ratio, hole concentration, hole mobility and resistivity of the 1.5–2 mol% NiO-doped AZO films were 0.26–0.29, 0.06–0.09, 3.15 × 10 18 –2.18 × 10 20 cm − 3 , 2.33–12.76 cm 2 /Vs, and 2.39 × 10 − 1 –1.24 × 10 − 2 Ω cm, respectively. I–V measurements of the p–n junction (ITO/NiO:AZO) revealed rectifying I–V characteristics, confirming that these NiO:AZO films exhibit p -type conductivity. This study opens the possibility of developing highly conductive p -type composite transparent conducting oxides for optoelectronic devices.

Znic sulfide (ZnS) thin films were deposited on glass substrates by radio frequency magnetron sputtering. The substrate temperature varied from room temperature (RT) to . The structural and optical properties of ZnS films were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive analysis of X-ray (EDAX) and UV-visible transmission spectra. The XRD analyses reveal that ZnS films have cubic structures with (111) preferential orientation, whereas the diffraction patterns sharpen with the increase in substrate temperatures. The FESEM images indicate that ZnS films deposited at have nano-sized grains with a grain size of ~ 67 nm. Then films exhibit relatively high transmittance of 80% in the visible region, with an energy band gap of 3.71 eV. One obvious result is that the energy band gap of the film increases with increasing the substrate temperatures.

A proof-of-concept of applying laser micro-machining to fabricate high performance GaN light-emitting diode (LED) was presented in this study. Laser micro-machining was applied to fabricate GaN LED chip with angled sidewalls (ALED). The inclined sapphire sidewalls were coated with highly reflective silver film which functions as an efficient light out-coupling medium for photons within the LED structure. Thus, more laterally-propagating photons can be redirected to the upward direction of the ALED with silver coating (Ag-ALED). Performances of the Ag-ALED, ALED and conventional planar GaN LED were evaluated. At an injection current of 30 mA, the light output intensity of Ag-ALED was significantly improved by 97% and 195% as compared to ALED and conventional planar LED, respectively. The corresponding wall-plug efficiency of Ag-ALED was remarkably increased by 95% and 193% as compared to ALED and conventional planar LED, respectively. The results of this study demonstrated that the Ag-ALED showed a pronounced increase in light output intensity compared to conventional planar LED, which may have many potential applications in the field of display engineering.

(Pb 0.92 La 0.08 )(Zr 0.65 Ti 0.35 )O 3 (PLZT) thin films with TiO 2 buffer layers were deposited on Pt/Ti/SiO 2 /Si substrates by R.F. magnetron sputtering method in order to improve the ferroelectric characteristics of the films; and the ferroelectric properties and crystallinities of the PLZT thin films were investigated in terms of the effects of the post-annealing temperatures of TiO 2 buffer layers between a Pt bottom electrode and a PLZT thin film. The ferroelectric properties of the PLZT thin films improved as the post-annealing temperatures of TiO 2 layers increased, reaching their maximum at 600 °C and decreasing thereafter.

PLZT ferroelectric thin films were deposited on Pt/Ti//Si substrate with buffer layer in between by rf magnetron sputtering method. In order to investigate the effect of Ar/ partial pressure ratio on the ferroelectric properties of PLZT thin films, PLZT thin films were deposited at various Ar/ partial pressure ratio ; 27/1.5 seem, 23/5.5 seem, 21/7.5 seem and 19/9.5 seem. The crystallinities of PLZT thin films were analyzed by XRD. The surface morphology was observed using FE-SEM. The P-E hysteresis loops, the remanent polarization characteristics and the leakage current characteristics were obtained using a Precision LC. The crystallinity and elaborateness of PLZT thin films were decreased as increasing the oxygen partial pressure ratio. And preferred orientation of PLZT thin films changed from (110) plane to (111) plane. The oxygen partial pressure ratio affects the thin film surface morphology and the ferroelectric properties.

PLZT thin films were deposited on platinized silicon (Pt//Si) substrate by RF magnetron sputtering. A buffer layer was fabricated, prior to deposition of PLZT films. the layer was strongly affected the crystallographic orientation of the PLZT films. X-ray diffraction was performed on the films to study the crystallization of the films as various substrate temperatures (Ts). According to increasing Ts, preferred orientation of films was changed (110) plane to (111) plane. The ferroelectric, dielectric and electrical properties of the films were also investigated in detail as increased substrate temperatures. The PLZT films deposited at showed good ferroelectric properties with the remnant polarization of and leakage current of .

Lanthanum modified lead zirconate titanate thin films were fabricated on indium-doped tin oxide (ITO)-coated glass substrate by R.F. magnetron sputtering method. The thin films were deposited at 500 °C and annealed at various temperatures (550 ~ 750 °C) by rapid thermal processing. The structure and the morphology of the films were measured by an X-ray diffraction and an atomic force microscope. The hysteresis loops and the fatigue properties of thin films were measured by a precision material analyzer. As the annealing temperature increased, the remnant polarization value increased whereas the coercive field was reduced. In our switching polarization endurance analysis, the remnant polarization of PLZT thin films annealed at 750 °C decreased after 109 switching cycles in the form of square waves.

(PLZT) thin films with buffer layers were deposited on Pt/Ti//Si substrates by an R.F. magnetron sputtering method in order to improve the ferroelectric characteristics of the films. And the ferroelectric properties and crystallinities of the PLZT thin films were investigated in terms of the effects of the post annealing temperatures of buffer layers between a platinum bottom electrode and PLZT thin film. The ferroelectric properties of the PLZT thin films improved as increasing of the post annealing temperatures of layers, thereby reaching their maximum at .

We report on a strong violet luminescence emitted from the ZnO:Al films grown on glass substrate by radio-frequency magnetron sputtering. The growth of high-quality thin films and their optical properties are controlled by adjusting the mixture ratio of Ar and , which is used as the sputtering gas. The crystallinity of the films is improved as the oxygen flow ratio is decreased, as evidenced in both x-ray diffractometer and atomic force microscope measurements. As for the violet luminescence measured by photoluminescence (PL) spectroscopy, the peak energy and intensity of the PL signal are decreased with increasing the oxygen flow ratio. The peak energy of the violet PL spectrum for the thin film with an oxygen flow ratio of 50 % is almost constant, regardless of the increase of laser Power and temperature. These results indicate that the violet PL signal is probably due to defects related to interstitial Zn atoms.

In this study, we investigated the structural and optical properties of indium sulfide (In2S3) thin films as a substitute for the CdS buffer layer in Cu(In,Ga)Se2 (CIGS) solar cells. The In2S3 films were deposited on glass substrates using radio frequency (RF) magnetron sputtering. The sputtering power was changed from 60 to 120 W in 20 W increments. The effects of sputtering power on the crystallinity, surface morphology, and optical properties of the films were characterized with X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), and UV-visible spectrophotometry. The XRD analyses indicated that the films were polycrystalline β-In2S3 structures with two preferred orientations along the (103) and (206) directions. The AFM images revealed that the films had nanosized grains and that the size increased from 7 nm for the samples prepared at 60 W to 13 nm for those prepared at 120 W. The optical band gap of the samples was found to vary between 2.88 and 2.43 eV.

R.F. magnetron sputtering법을 이용하여 Pt/Ti/SiO₂/Si 기판 위에 Pb 1.1 Zr 0.53 Ti 0.47 O₃ target을 사용하여 박막을 제조하였다. Interlayer(PbO, TiO₂, PbO/TiO₂)층을 삽입함으로써 박막의 결정성을 향상시켰고, 박막의 기판온도도 상당히 낮출 수 있었다. 순수한 PZT에 비하여 interlayer를 삽입한 PZT는 높은 유전상수과 낮은 유전손실 및 높은 누설전류를 가지는 우수한 전기적 특성을 나타내었다. 이러한 PZT 박막과 interlayer 층은 증착온도에서 서로 반응하여 하나의 고용체를 이루지 않고, 각각 독립적인 층으로 존재함을 XPS 분석을 통해 확인하였다. 여러 interlayer중 특히 PbO/TiO₂는 우수한 유전특성(e r =414.94, tanδ=0.0241, Pr=22 μC/㎠)을 나타내었고 가장 효과적인 seed로써의 역할을 하였다.

Zinc sulfide [ZnS] thin films were deposited on glass substrates using radio frequency magnetron sputtering. The substrate temperature was varied in the range of 100°C to 400°C. The structural and optical properties of ZnS thin films were characterized with X-ray diffraction [XRD], field emission scanning electron microscopy [FESEM], energy dispersive analysis of X-rays and UV-visible transmission spectra. The XRD analyses indicate that ZnS films have zinc blende structures with (111) preferential orientation, whereas the diffraction patterns sharpen with the increase in substrate temperatures. The FESEM data also reveal that the films have nano-size grains with a grain size of approximately 69 nm. The films grown at 350°C exhibit a relatively high transmittance of 80% in the visible region, with an energy band gap of 3.79 eV. These results show that ZnS films are suitable for use as the buffer layer of the Cu(In, Ga)Se2 solar cells.

【Alumina dispersion strengthening copper(ADSC) alloy has great potential for use in many industrial applications such as contact supports, frictional break parts, electrode materials for lead wires, and spot welding with relatively high strength and good conductivity. In this study, we investigated the oxidation behavior of ADSC alloys. These alloys were fabricated in forms of plate and round type samples by surface oxidation reaction using Cu-0.8Al, Cu-0.4Al-0.4Ti, and Cu-0.6Al-0.4Ti(wt%) alloys. The alloys were oxidized at $980^{\circ}C$ for 1 h, 2 h, and 4 h in ambient atmosphere. The microstructure was observed with an optical microscope(OM) and a scanning electron microscope(SEM) equipped with energy-dispersive X-ray spectroscopy(EDS). Characterization of alumina was carried out using a 200 kV field-emission transmission electron microscope(TEM). As a result, various oxides including Ti were formed in the oxidation layer, in addition to ${\gamma}$ -alumina. The thickness of the oxidation layer increased with Ti addition to the Cu-Al alloy and with the oxidation time. The corrected diffusion equation for the plate and round type samples showed different oxidation layer thickness under the same conditions. Diffusion length of the round type specimen had a value higher than that of its plate counterpart because the oxygen concentration per unit area of the round type specimen was higher than that of the plate type specimen at the same diffusion depth.】