Write-Once Optical Disk Using Ge-Sb-Te/Bi-Te Bilayer Film for Mark-Edge Recording

Abstract

The Ge-Sb-Te/Bi-Te bilayer has been developed as a recording layer for a write-once optical medium. Mark-edge recording is carried out using the bilayer, and the (1, 7) run-length-limited code is employed for mark-edge recording. Without waveform equalization, the bilayer has a wide recording power tolerance of ±33% with a linear density of 0.68 µm/bit. This linear density corresponds to ∼9 Gbytes for both sides of a 300-mm disk with a modified constant angular velocity mode. Furthermore, the alloying states along the cross section of the bilayer are measured by energy-dispersive X-ray spectroscopy after laser recording at 9 and 15 mW.