| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase transition type optical recording medium which has the capacity equal to that of DVD-ROM, has the interchangeability with the DVD-ROM and is excellent in productivity. SOLUTION: In this phase transition optical recording medium where the recording to a groove part of substrate is performed with a medium composition which is made by laminating a first dielectric layer, a recording layer, a second dielectric layer and a reflecting layer in this order, the following requirements are stipulated. (a) The thickness UL of the first dielectric layer, the thickness PL of the recording layer, the thickness TL of the second dielectric layer and the thickness RL of the reflecting layer are respectively in the following range: 30 nm<UL<250 nm, 8 nm<=PL<=25 nm, 10 nm<=TL<=200 nm, 30 nm<=RL<=200 nm. (b) The recording layer has main constituent elements of Ag, In, Sb and Te. (c) N2 is added to the recording layer. (d) The first and second dielectric layers consist essentially of ZnS and SiOx. (e) The depth Dg (nm) of the groove part is 0.03λ<Dg<0.095λ, therein, λ (nm) is recording and reproducing wavelength. (f) 2.0<na (refractive index of amorphous state)<4.0, 2.5<ka (absorption coefficient of amorphous state)<3.5, 1.0<nc (refractive index of crystalline state)<3.5, 3.0<kc (absorption coefficient of crystalline state)<4.5. |
