Blue-laser readout properties of super resolution near field structure disc with inorganic write-once recording layer

A novel inorganic write-once recording material SbN(x) (antimony nitride) was proposed for super resolution near field structure (super-RENS) discs. The layer structure is polycarbonate substrate (0.6 mm)/ZnS-SiO(2) (170 nm)/AgO(x) (15 nm)/ ZnS-SiO(2) (40 nm)/SbN(x) (25 nm)/Ag (100 nm)/UV-curing resin/dummy PC substrate (0.6 mm). The recording layer with high-contrast characteristics enhanced the readout signal, which was compared with that of conventional phase-change materials. The carrier-to-noise ratio (CNR) of 150 nm mark length was about 44.2 dB at a readout power of 2.5 mW using blue laser. A below-diffraction-limited mark length as short as 60 nm can be readout using blue laser of 405 nm with a lens having a numerical aperture of 0.65.