Single-beam overwrite experiment using In-Se based phase-change optical media

Abstract

Single-beam overwrite in an optical disk is reported using In-Se-Tl amorphous-crystalline phase-change recording films having very short erasing (crystallization) time of 0.2 μs. The lifetime of the amorphous state in an In-Se-Tl film is estimated to be longer than 10 years at 60 °C. This is due to its high crystallization temperature (135 °C) and high activation energy (2.6 eV). The phase-change cycles can continue over 106 cycles in stationary state experiments using test samples. The possibility of single beam overwrite (rewriting without prior erasing as with a magnetic disk) is verified by using a 1.6-μm-diam round laser beam spot irradiated on a 5-in.-diam disk rotating at 2400 rpm.

ModelingIn−Seamorphous alloys

“…Such type of experiments with InSe were first performed by Nishida et al using a laser pulse. 10 Recently, however, it has been suggested that electron beam sources could be used for amorphization or crystallization in order to create smaller amorphous spot size. The readout process would then also be via the electrons and the actual device is proposed to be a thin film p-n junction.…”

Modeling InSe Phase-change Materials

“…Indium monoselenide (InSe) is a phase-change material: both the crystalline and the amorphous phases are stable at room temperature [1]. Beside applications such as solar cells and ionic batteries, InSe has recently attracted considerable attention because of its potential application as a data storage medium.…”

Phase Change Optical Storage - A Critical Assessment

“…Early experiments resulted in 46db CNR and 14db erasability with the structure: IOOnm Zr02 / InSeTl/ lOOnm Zr02/ 2P / glass [11]. However, most data has been obtained using GeSbTe recording layer compositions.…”

“…Another group of fast materials crystallizes into a state which has lower reflectivity than the amorphous state. These include In3SbTe2[151, compositions along the InSb-GaSb tieline [3] ,and InSeTl [ 11]. The general criterion for selecting fast crystallizing media is to choose compositions which are at or near single phase stoichiometric regions of the phase diagram [lO] or that crystallize into single phase me tastable structures [3].…”