Super-Resolution Near-Field Phase Change Disk with Sb₇₀Te₃₀ Mask Layer

Super-resolution near-field phase change optical disks with a new mask layer of Sb70Te30 were studied. Disks with two different structures were analyzed using optical and thermal simulation methods. The simulation results showed that the optical disk exhibited maximum response when nearly half the laser spot was covered by the mask. The fast response depended on optimizing both the disk structure and reading power to match a certain speed because the effect of super-resolution near-field structure (super-RENS) was related to the position between the laser beam and the hole formed in the mask layer. Experimental results showed that the disk with a thermal shield layer, which was inserted into the dielectric layer located between the mask layer and the phase change layer, demonstrated a better thermal stability than the disk without the thermal shield layer. This is in good agreement with simulation results. Recording marks as small as 62 nm were observed.