A Novel Approach to Obtain GeSbTe-Based High Speed Crystallizing Materials for Phase Change Optical Recording
- PDF / 110,299 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 60 Downloads / 212 Views
A Novel Approach to Obtain GeSbTe-Based High Speed Crystallizing Materials for Phase Change Optical Recording
Tae-Yon Lee1, Byung-ki Cheong, Taek Sung Lee, Sung Jin Park, Won Mok Kim, Kyung Seok Lee, Ki-Bum Kim1, and Soon Gwang Kim 1 School of Materials Science and Engineering, Seoul National University, Shilim-dong, Kwanak-gu, Seoul 151-742, Korea. Materials Design Laboratory, Korea Institute of Science and Technology, Hawolgok-dong, Sungbuk-ku, Seoul 136-791, Korea.
ABSTRACT A new approach is proposed to obtain fast crystallizing materials based on a conventional GeSbTe alloy for rewritable phase change optical data storage. By means of co-sputtering, Ge1Sb2Te4 alloy was mixed with Sn1Bi2Te4 alloy so as to form pseudo-binary alloys (Ge1Sb2Te4)1-x(Sn1Bi2Te4)x (x is a mole fraction). From structural and optical analyses of the cosputtered and annealed alloy films, the formation of stable crystalline single phases was observed along with a Vegard’s law behavior, suggesting a homogeneous mixing of the two alloys. By use of a 4 layered disk with (Ge1Sb2Te4)0.85(Sn1Bi2Te4)0.15 recording layer, a preliminary test of writing and erasing was carried out and the results were compared with the case of the disk with Ge1Sb2Te4 recording layer. The (Ge1Sb2Te4)0.85(Sn1Bi2Te4)0.15 recording layer was found to yield markedly higher erasibility, especially with increasing disk linear velocity.
INTRODUCTION With a rapid progress of information and communication technology, there has been growing need for higher density and higher speed information storage. As for phase change optical data storage, boost in recording density and data transfer rate has been achieved primarily by ways of reduction in beam spot size and/or increase in disk linear velocity. Beam dwell time, expressible in terms of beam spot size divided by linear velocity, has diminished accordingly. This has led to a sustaining demand for faster crystallizing recording materials. In the cases of the GeSbTe alloys, enhanced crystallization kinetics has been attained by modification of alloy composition through addition of single elements such as Au, Pb[1,2], N[3], Sn[4] , Bi[5] and/or by use of V1.7.1
crystallization promoting layers such as SiC, GeN[6,7]. In this report, we propose a novel approach that may be utilized to promote the crystallization kinetics of the GeSbTe alloys. In doing so, we address specifically the case of the stoichiometric Ge1Sb2Te4 alloy that is presently in wide use besides Ge2Sb2Te5 alloy.
PROPOSED APPROACH AND EXPERIMENTAL ALLOY SYSTEM G
The present approach hinges on a well-known fact that a stoichiometric compound alloy tends to have faster kinetics of amorphous to crystalline transformation since only short range atomic reconfiguration would attend the transformation.G An interesting question arises; suppose a stoichiometric alloy is mixed with another alloy that has the same stoichiometry but with a stronger tendency for crystallization, would the resulting alloy have an enhanced crystallization kinetics ? Herein, we mix Ge1Sb2Te4
Data Loading...
