Materials Issues in Blue Recording

Abstract

In the development of materials for blue recording, the issues for rewritable discs relate to speed and lifetime stability. Both aspects are connected with the properties of the phase-change recording layer. Higher data rates require faster erasure (i.e., recrystallization) of previously written marks. Increasing the Sb concentration or adding specific dopants to the phase-change material appears to accelerate the crystallization rate. Faster erasure rates should, however, not promote spontaneous recrystallization at room temperature, as this would adversely affect the lifetime stability. This roomtemperature stability can be estimated from an activation energy analysis. Excellent lifetime stability proves attainable by a judicious selection of the composition of the phase-change material.For write-once discs, the choice of the recording material is between a spin-coated dye, a phase-change layer, and an inorganic alloy. While suitable dye materials for blue wavelengths are now being developed, research into the alternative of inorganic bilayers has yielded encouraging results. Thus far, good write-once recording performance has been demonstrated with Cu/Si as the recording medium.The mechanism of mark formation in such a bilayer will be addressed. Promising results obtained with optimized Cu/Si stacks illustrate the attractiveness of this type of write-once material for blue recording.

Microstructure and recording mechanism of Bi–Fe–(N) layer for high-density write-once optical disk

“…5 For write-once disks, various organic and inorganic recording materials have been proposed. 6 Inorganic-type materials include phase-change alloys, 7 single-layer AlSi alloys, 8 bilayer metals such as Cu/ Si, 9 Zn/ Ge, 10 Ge/ Au, 11 Cu/ a-Si, 12 etc. Among these, Bi-related alloys such as Bi-Ge alloy 13,14 and Bi oxide ͑BiFeO͒ 15,16 exhibit promising applications for write-once data storage.…”

Influence of Surrounding Dielectrics on the Data Retention Time of Doped Sb2Te Phase Change Material

“…The layer stack consists of a doped Sb 2 Te PC material sandwiched by a dielectric layer underneath (DL1) and a dielectric layer on top (DL2) of the PC material. 2,3) Both ZnS:SiO 2 and SiO 2 were separately used for DL1 and DL2, hence obtaining a matrix of 4 different discs, see Table I. Prior to the deposition of each layer, the disc was exposed to ambient air in order to allow transportation into the subsequent deposition chambers.…”

Phase-Change Kinetics of Bi–Fe–(N) Layer for High-Speed Write-Once Optical Recording

“…[1][2][3] According to the data recording principle, optical disks can be divided into read-only memory (ROM), write-once/recordable (R), and rewritable (RW). Among these, the write-once type is always the dominant product in the optical disk market and much effort has been exerted into studies of recording materials, either organic or inorganic, 4) for such a type of optical disk. At present, recording materials compatible with blue-laser recording are of particular interest.…”