ブルーレーザー対応型光ディスクにおける特性の改善 Improvement of Characteristics on Optical Disk at the Wavelength of Blue Laser
Thin films (of 50 nm thick) with a stacked structure (of 10150 layers) of In<SUB>2</SUB>O<SUB>3</SUB> and ZnO have been deposited onto the glass and the polycarbonate substrates using the split target consisting of In<SUB>2</SUB>O<SUB>3</SUB> and ZnO by a pulsed laser technique with an ArF excimer laser. A relation of the transmittance change ΔT at the wavelength of 400 nm between the annealed state (480°C × 20 min) and the as-deposited state versus the number of layers for the structure fabricated at the trace ratio of In<SUB>2</SUB>O<SUB>3</SUB> : ZnO = 1 : 1 was obtained. The structure with 20 layers showed the maximal value of ΔT. SEM observation revealed that the surfaces of these films were enough smooth to use in static or revolution tests for'write'. AFM observation showed that surface roughness of the as-deposited state and the annealed state were Ra of 0.76 nm and Ra of 2.25 nm respectively. A peak power dependence of CNR of 3T signal (λ = 406 nm, NA = 0.65) at a linear velocity of 5 m/s and a read power of 0.6 mW was measured for the disk samples with 60-layers fabricated for the revolution tests. That the write power of less than 3 mW was required and maximal value of CNR = 67 dB was obtained. The values of CNR could be improved by optimizing the number of layers and the film compositions.
真空 45(3), 247-250, 2002-03-20
The Vacuum Society of Japan