Abstract: An information recording medium includes a substrate and an information layer formed on the substrate. The information layer includes a recording layer whose phase can be changed between a crystalline phase and an amorphous phase by irradiation with a laser beam or application of electric energy; a Cr-containing layer including at least Cr and O, arranged in contact with a first surface of the recording layer; and a Ga-containing layer including at least Ga and O, arranged in contact with a second surface of the recording layer.

Abstract: In an information recording medium of the present invention, a recording layer and first and second dielectric layers are formed on a surface of a substrate. In the recording layer, at least one of recording and reproduction is caused by irradiation of light or application of electric energy. The dielectric layers are oxide-based material layers or oxide-nitride-based material layers containing an oxide of at least one element selected from the group GM consisting of Sn, Ga and Zn, and at least one of an oxide and a nitride of at least one element selected from the group GL consisting of Al, Si and B, or oxide-fluoride-based material layers containing a fluoride of at least one element selected from La and Ce, and one example of at least one of element selected from the group GM.

Abstract: The information recording medium of the present invention comprises at least one of the following oxide-based material layers: (I) an oxide-based material layer containing Zr, at least one element selected from the group GL1 consisting of La, Ga and In, and oxygen (O); (II) an oxide-based material layer containing M1 (where M1 is a mixture of Zr and Hf, or Hf), at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y, and O; (III) an oxide-based material layer containing at least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2, Si, and O; and (IV) an oxide-based material layer containing at least one element selected from the group GM2, at least one element selected from the group GL2, Cr, and O. This oxide-based material layer can be used, for example, as a dielectric layer.

Abstract: An optical recording medium having a light absorption layer formed on a substrate having a spiral groove by means of the vacuum deposition and a reflective layer formed on the light absorption layer, wherein: (1) the groove of the substrate has a groove section of which cross section is a trapezoidal; (2) a ratio of a groove width (W) to a track pitch (TP) (W/TR) of the substrate falls within a range of 0.25 to 0.45; (3) a groove depth (D) is 20 to 80% of (&lgr;/4n) (wherein A is a wavelength of a laser beam, and n is a refractive index of the substrate); and (4) angles a1 and a2 formed by both side surfaces of the groove section and surfaces vertical to a groove bottom surface on cross lines between the both side surfaces of the groove section and the groove bottom surface are 45 to 80°, and a difference between a1 and a2 (a1−a2) is not more than ±10°.