Phase-Change Media for High-Numerical-Aperture and Blue-Wavelength Recording

Abstract

We have studied the feasibility of doped eutectic SbTe alloys for practical application in digital video recording (DVR) rewritable phase-change media for high-numerical-aperture (NA=0.85) and blue-wavelength (λ=405 nm) recording. Remaining issues such as thermal cross-erase in land/groove recording and the thermal stability of recorded amorphous marks have been investigated and resolved. This work has resulted in the realisation of 22.5 GB phase-change media complying with the DVR blue format. The future of doped eutectic SbTe alloys in the phase-change recording-speed race is also promising, as the crystallisation speed and archival life stability can be optimised more or less independently by tuning the Sb/Te atomic ratio and adding Ge, respectively. We have demonstrated that a user data transfer rate of 70 Mbit/s (DVR double speed) is within reach using our current phase-change composition, and are expecting to realise data rates of over 100 Mbit/s in the near future.