Tzuan-Ren Jeng

Microstructure and recording mechanism of Ge∕Au bilayer media for write-once optical disc

The recording mechanism of Ge∕Au bilayer and its dynamic tests for write-once blue laser high density DVD (HD DVD) are investigated. It is found that Ge2Au3 phase is nucleated between amorphous Ge and crystalline Au layer after room temperature deposition. Crystallization of Ge∕Au interface layer at 170–190°C is induced by the nucleated Ge2Au3 sites at the interface, the bilayer structure is further heated to 200–450°C. After heating above 320°C, crystallized Ge are segregated at the grain boundary. The dynamic test results show that this Ge∕Au bilayer films can be applied to 1×–2× HD DVD-R.

Diffusion and crystallization mechanisms of Ge/Au bilayer media for write-once optical disk

Ge∕Au bilayer thin films were fabricated by magnetron sputtering method, the temperature dependence of resistance from room temperature to 500°C and concentration depth profiles are measured. From the temperature dependence of resistance measurement, we found two phase change phenomena which occurred at 175 and 360°C. The element concentration depth profiles of the as-deposited and recorded region indicate that the Au–Ge alloy is initially formed at the Ge∕Au interface. The dominant diffusion element is Au atom and the diffusion path is from Au layer to Ge layer. The optimum simulated bit error rate value is about 1.4×0−6 at 9.0mW under two time high definition digital versatile disk (HD DVD) recording speed. The dynamic tests show that this Ge∕Au bilayer films can be applied to one to two times HD DVD-R.

GeCu Thin Films for Inorganic Write-Once Media

The Ge100-xCux thin films (x=50 at.%-69 at.%) were deposited on nature oxidized Si (100) wafer by dc co-sputtering of Ge and Cu targets. Microstructures was analyzed by X-ray diffractometer. The optical and thermal properties were measured from static test. It was found that the as-deposited phase was single supersaturated epsiv-Cu3Ge phase and it was transformed to Ge and epsiv-Cu3Ge coexisting phases after annealing at 400degC. The reflectivity of as-deposited film was higher than that of annealed film

Method of magnetic domain modeling on a moving magneto‐optical disk

A method is proposed to simulate the formation process and the shape of a magnetic domain on a moving magneto‐optical disk. It is assumed that the direction of the force acting on the domain wall is perpendicular to the isothermal line of the critical temperature. Slicing lines perpendicular are taken at regular intervals to this isotherm, and by applying the one‐dimensional bubble model the wall position on each slicing line is determined. Connecting the wall positions in each time frame the evolution of the domain shape in the formation process is obtained. By applying this method to Tb23Fe77 thin film, it is found that the domain wall in Tb23Fe77 thin film on a moving disk was first pinned in the cooling region which was the leading region of laser exposure on the disk, then the pinned wall expanded toward the heating region, and a closed domain was formed after the laser was turned off.

Angular distribution of the sputtered atoms from TbFeCo targets

The angular distribution of the sputtered Tb, Fe, and Co atoms from the elemental targets could be described by cosn θ distribution with n=1.90, 0.54, and 1.01 for Tb, Fe, and Co, respectively. For TbFeCo composite targets with mixed elemental and intermetallic compound phases, the overall angular distribution of the sputtered Tb, Fe, and Co atoms from the mixed phases could also be described by the cosn θ distribution function, and the values of the n’s were related to the volume percentage of the intermetallic compound content in the composite target. This was not true of the Tb distribution for a target containing high intermetallic compound content. In that sample, an off‐normal term has to be added to the cosn θ distribution function. It was found that a composite target with about 23 vol % intermetallic compound would produce a uniform composition distribution of TbFeCo film on the substrate.

New 3D Image Technologies Developed in Taiwan

Some new 3D image technologies including image capturing, digital data processing, 2D/3D video conversion, and naked eye 2D/3D compatible display have been developed in Taiwan for the future 3D world applications. An innovative 3D image capturing and displaying architecture is a cost effective system for 3D content generation, transmission, and display. The multiview images of fine art such as sculpture can be captured by using 3D scanner or camera. The obtained multiview images can be transmitted though popular streaming channel to the cloud computing center that handles huge tasks of 2D/3D image processing. Then, the multi-view images are fed into the new types of 2D/3D compatible display. This new type of display using a specially designed microretarder can present 2D and naked eye 3D images on the same display simultaneously. Some new 3D applications with real-time 2D to 3D conversion technology are also introduced.

New Optical Storage Format and Technologies Developed in Taiwan

The new optical disk format, called forward versatile disk (FVD), has been developed in Taiwan. Some physical technologies, such as recording on narrower groove, new modulation code, and new error correction code (ECC) have been verified. The feasibility for producing triple-layer FVD has been proven. In addition to the read-only memory (ROM) type, the format for the recordable/rewritable FVD type is also developed. These technologies of FVD with red laser will be applied to the next generation. Blue high-definition (HD) FVD will adopt most red HD FVD technologies. For higher recording capacity FVD, technologies such as super-RENS and multilevel recording for next-generation FVD are continuing to develop

Tilt-Target Magnetron Sputter for Deposition of Magnetooptical Disk

A 3.5-inch magnetooptical disk is made by tilting the TbFeCo target in a DC circular magnetron sputtering process. The composition of the recording layer is controlled by using the Tb-rich deposition area. The optimal tilt angle of our target for uniform radial composition distribution on the disk is found to be about 15°. A model was proposed to explain the observed Tb, Fe and Co content variation with the tilt angle of the target. The dynamic read/write test also showed that good carrier to noise ratio (CNR) was obtained at this angle. A new deposition process for magnetooptical (M-O) disk based on the tilt target method is proposed; it has the merits of enabling simultaneous deposition of multiple disks. The CNR of the disk made at 15° tilt angle is 53 dB.

Ellipsometric measurement of magneto-optical Kerr rotation at normal incidence

Two simple methods were introduced for measuring the magneto‐optical Kerr rotation when the light is incident upon the surface of the magneto‐optical media at zero degree angle of incidence. The methods can readily be implemented on an existing ellipsometer.

Performance Analysis for Multiview Auto-Stereoscopic Floating Images

In this paper, we analyze and discuss the problem of lens distortion in 3-D floating images. Lens distortion impacts the viewing zone distribution of auto-stereoscopic images. To understand the relationship between lens distortion and stereoscopic effects, we set up measurement methods to evaluate them. Measured data from these methods allow us to easily determine the optimization results of the 3-D floating image system. It will help to improve the 3-D floating display system when we try to optimize its optical design and user interface.