Patent ID: 8437235

Claim:
An optical information recording medium comprising an information layer that allows information to be recorded thereon and reproduced therefrom by irradiation with a laser beam, wherein: the information layer includes at least a reflective layer, a first dielectric layer, a recording layer capable of undergoing a phase change by the irradiation with the laser beam and a second dielectric layer formed in this order from a side opposite to a laser beam incident side; the recording layer contains Ge, Sb and Te, and when Ge, Sb and Te contained in the recording layer are represented by Ge x Sb y Te z in atomic number ratio, x, y, and z satisfy 0.39≦x<0.48, 0.02≦y<0.11, 0.41<z<0.56, and x+y+z=1; the recording layer has a thickness of at least 10 nm but not more than 15 nm; and in the case where a ratio of an amount of reflected light of the laser beam from the information layer to an amount of the laser beam incident on the information layer is denoted as R (%), the R when the recording layer is in a crystalline state is denoted as Rc (%), and the R when the recording layer is in an amorphous state is denoted as Ra (%), Rc and Ra satisfy 6.0≦Rc/Ra≦12.0 and 1.0≦Rc≦3.0.