Koichi Kotera

Million Cycle Overwritable Phase Change Optical Disk Media

GeTe-Sb2Te3-Sb pseudo ternary components alloy shows laser induced rapid crystallization and amorphous change phenomena. Films of non stoichiometric GeTe-Sb2Te3-Sb can be crystallized using laser pulses less than 100ns duration. The crystalline structure shows the cubic structure. The time it takes to laser crystallize varies Sb concentration. And increasing the Sb concentration leads to increased crystallization temperature. The crystallization temperature of 180 C and more than 1200h stable of acceleration test of 80C 80% RH environment. Thin film disk structure of 20nm active layer produce more than million cycle over-write BER(bit error rate) stability. I would like to discuss the degradation model of pinhole generation in phase change disk media.

Temperature Dependence of Conductivity of Nitrogen-Containing Diamondlike Carbon Films Deposited from Pyridine

We investigated the effects of atmospheric and substrate temperatures on diamondlike carbon (DLC) films prepared by biased thermal-filament plasma chemical vapor deposition using vapor benzene and pyridine as a source. The DLC film deposited from pyridine which contains a nitrogen atom was conductive. Although the conductivity was dependent on the substrate temperature in the deposition process, the concentration of nitrogen and hydrogen in the conductive film was not. The reason for the dependence is the increase in number of hopping sites and the delocalization of π electrons with increasing substrate temperature.

New Write-Once Media Based On Te-Te02 For Optical Disks

Thin film media composed of Te-Te02 (TeOx) containing Pd additive was found to have a feasibility of being applied to high reliability data file optical disks. The carrier to noise ratio (C.N.R.) exceeds 56 dB at 1,200 r.p.m. disk rotation. The response time of saturation amplitude after a pulsed laser power irradiation was less than 300 nsec and is able to apply to high speed read verify systems. From acceleration environmental stress test results, no defect variation was observed. By the Arrhenius plot method, the disk life has been estimated to be more than 10 years at the storage environment 32 degree C, 80 %RH. The recording and degradation mechanism will be also discussed.