Chao-Te Lee

Crystallization mechanisms and recording characteristics of Si/CuSi bilayer for write-once blu-ray disc

The crystallization mechanisms of Si/CuSi bilayer and its recording characteristics for write-once blu-ray disc (BD-R) were investigated. It was found that Cu3Si phase appeared during the room temperature sputtered deposition. Then, the Si atoms in CuSi layer segregated and crystallized to cubic Si in Cu3Si nucleation sites as the film was annealed at 270 °C. After heating to 500 °C, the grains size of cubic Si phase grew and the hexagonal Si phase was observed. The dynamic tests show that the Si/CuSi bilayer has great feasibility for 1-4× BD-R with the bottom jitter values below 6.5%.

Effect of substrate temperature on the properties of ZrB2 film on Si(111) deposited by pulsed DC magnetron sputtering

The wurtzite GaN and related nitride films are typically grown on sapphire or SiC substrates. However, large lattice-mismatches between GaN and sapphire or SiC can lead to degradation of quality of grown GaN by 16 and 4%, respectively. ZrB2 is a semi-metal compound and has a hexagonal crystal structure. The a-axis lattice constant of ZrB2 is 3.168 A, which is almost lattice-matched to GaN. The thickness of ZrB2 film is 228 nm which was prepared on a Si(111) substrate by pulsed DC magnetron sputtering deposition. The effects of substrate temperatures ranging from 400 to 550 °C on the microstructure, resistivity and surface roughness of the deposited ZrB2 films were investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), the four-point probe technique and atomic force microscopy (AFM). XRD analysis revealed that the ZrB2 film had a polycrystalline structure and the preferred orientation was along (001) when the substrate temperature was above 450 °C. The relationship between the average grain size of the ZrB2 film and substrate temperatures ranging from 450 to 550 °C forms a downward parabolic function. The minimum average grain size of the ZrB2 film was 10.6 nm when the substrate temperature was 500 °C. The minimum resistivity of the ZrB2 film was 229 µΩ cm when the substrate temperature was 550 °C. The AFM measurements showed the ZrB2 films to have a uniform morphology with a very low surface roughness value of 0.2 nm. In this work, it was found that a uniform surface morphology and preferred orientation along (001) of the ZrB2 film on Si(111) could be obtained through pulsed DC magnetron sputtering when the substrate temperature was above 450 °C. This mirror-polished ZrB2 buffer layer is a good candidate for GaN film growth on Si(111) wafers.

WO 3 Electrochromic Thin Films Doped With Carbon

(WO₃)_100-XC_X thin films (x=0-9.3 at%) were cosputtered on indium-tin-oxide glass substrate with W and C targets by reactive dc magnetron sputtering at room temperature. The effects of doped C on the microstructure and optical properties of the (WO₃)_100-XC_X thin film were examined by field emission scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction, and a spectrophotometer. It was found that all of the as-deposited films were amorphous. The average transmittances of bleaching and colored WO₃ film in the 400-700 nm range were 75% and 65.9%, respectively. The variation in average transmittance of the bleaching and colored states of (WO₃)_90.7C_9.3 film was 68.3%. The average transmittance of bleaching (WO₃)_100-XC_X thin films did not vary with C doping. However, the average transmittance of colored (WO₃)_100-XC_X film decreased to <;48% after C doping. In addition, the optical transmittance contrast of (WO₃)_100-XC_X thin films was found to be suitable for blue laser wavelength recording.

Head-up display using an inclined Al2O3 column array

An orderly inclined Al2O3 column array was fabricated by atomic layer deposition and sequential electron beam evaporation using a hollow nanosphere template. The transmittance spectra at various angles of incidence were obtained through the use of a Perkin-Elmer Lambda 900 UV/VIS/NIR spectrometer. The inclined column array could display the image information through a scattering mechanism and was transparent at high viewing angles along the deposition plane. This characteristic of the inclined column array gives it potential for applications in head-up displays in the automotive industry.

Investigation on optical and electrical properties of ZnO sandwich structure with metal interlayer

The dielectric–metal–dielectric (DMD) sandwich structure is fabricated by the RF magnetron sputtering. The effects of sputtering voltage, thickness of the metal layer, and process temperatures on the optical, crystalline structure, and electrical properties of the zinc oxide (ZnO) films were investigated by UV–vis spectrometry, X-ray diffraction and electron energy loss spectroscopy (EELS). Silver, copper and aluminum are used for the DMD sandwich metal layer in this research. The thickness of the dielectric films is decided by admittance loci analysis base on the selected metal characteristic. The optical average transmittance in the visible spectrum and bulk resistivity of the DMD with intermediate Ag layer can reach 85% and 3 × 10−5 Ω cm, respectively.

Effects of CrRu Underlayer and CrRu Capped Layer on the Microstructure and Magnetic Properties of FePt Films

The magnetic properties and microstructure of CrRu/FePt bilayer and CrRu/FePt/CrRu trilayer deposited by dc magnetron sputtering on preheated natural-oxidized Si (100) wafer substrates were studied. It is found that both the in-plane coercivity (Hc//) and grain size of the FePt film increase with increasing the thickness of CrRu underlayer. The Hc// value of the FePt film is further increased but the grain size is decreased as adding a CrRu capped layer on the FePt film. The granular L10 FePt nanoparticles with in-plane coercivity of 2300 Oe and isolated uniform size of 6.61 nm are achieved from the CrRu(15 nm)/FePt(25 nm)/CrRu(4 nm) film deposited at a low substrate temperature of 350 degC

Relative reflectivity uncertainty evaluation for a broadband spectrophotometer system

This study aims to analyze the reflectivity measurement uncertainty of a spectrophotometer, with considerations of the perpendicular incidence/reflection, scattering, and artificial manipulation. The operation procedure is designed to utilize a double beam spectrophotometric system, taking advantage of the direct comparison of the luminous intensity to evaluate the uncertainty. The environmental range of the temperature and the relative humidity for the measuring process are controlled to be 23±1.5oC and 50%±10%, respectively. The range for correction reflectivity is 10%-100%. High-reflectivity standard parts are used with the integrating sphere for the calibration. Low-reflectivity standard parts are used along with an integrating sphere for the evaluation when the measurement reflectivity is 0%-9%. The optimal expanded composition uncertainty of the system is found to be 1.2% in the wavelength range of 400 nm-700 nm.

Investigation of the Microstructure, Porosity, Adhesion, and Optical Properties of a WO 3 Film Fabricated Using an E-Beam System With Ion Beam-Assisted Deposition

The relationship between the oxygen pressure, porosity, adhesion, and ion beam-assisted deposition (IAD) conditions for WO₃ electrochromic films prepared using an electron-beam (E-beam) system was investigated. The adhesion of thin films on the substrate by sole E-beam system is very weak. The best method is proposed to obtain good adhesion and better porosity by combining the E-beam evaporation, and the microstructure and coloration efficiency were determined using a field emission scanning electron microscope (SEM) and a spectrometer, respectively. Notably, the effect of the oxygen pressure on the coloration efficiency and porosity of Ta₂O₅/WO₃ films was found to be different. The optimal average transmittance of the electrochromic film in the bleached state was 11%, and in the colored state was 68%, when a Ta₂O₅ thin film was deposited in oxygen at a pressure at 9 × 10^-4 torr using IAD, and a WO₃ thin film was deposited at an oxygen pressure of 7.5 × 10^-5 torr. The studied results are useful for the design of more efficient photoelectrochemical devices employing evaporated WO₃ films.

CuSi thin film for write-once blue laser optical recording

The thermal property, optical property and recording characteristics of the CuSi (16 nm) film were investigated. The optimum jitter value of the film with 1X recording speed is 7.5% at 6 mW.

Development of high-performance parallel exposure I-line UV light source

UV light source and high-pressure mercury lamps are usually used as a projecting light source of foreign exposure light source recently, including a spherical mirror ellipse, an optical integrator, and a parallel lens. The light source system is the most crucial technology to achieve better image quality and better uniformity of light field. High-stability, high-uniformity, and high-parallelism light source should be created to ensure the stability of all processes. In this research, two sets of Flys eye lens are used as an optical integrator for combining with the redesigned parallel lens, which are evaporated AR coating to increase the transmittance of overall optical system up to 80% and the uniformity of light field. Equivalent doublets are also proposed to improve the original design of single parallel lenses for reducing the thickness, curvature, and divergent angle of a single lens so as to enhance the efficiency of light irradiation.