High-Density Read-Only Memory Disc with Ag₁₁In₁₂Sb₅₁Te₂₆ Super-Resolution Mask Layer

A novel read-only memory (ROM) disc with an Ag₁₁In₁₂Sb₅₁Te₂₆ super-resolution mask layer is proposed and investigated for the first time to our knowledge. The carrier-to-noise ratio of more than 40dB could be obtained from small pits (380nm), which are below the readout resolution limit (400nm), in our dynamic setup with a wavelength of 632.8nm and numerical aperture of 0.40. Dependences of carrier-to-noise ratio on readout power, readout velocity and film thickness are studied. The results show that the optimum film thickness is 20-50nm and the corresponding carrier-to-noise ratio is more than 40dB at readout power of 4mW and readout velocity of 2m/s in our experiment. The super-resolution readout mechanism for this ROM disc is also discussed.