Abstract: Disclosed is a read-only optical information recording medium which comprises a reflective film having a reflectance suitable for use as a reflective film for an optical information recording medium (e.g., BD-ROM) and having excellent reproduction stability, and which utilizes a blue laser beam. Specifically disclosed is a read-only optical information recording medium comprising a reflective film, wherein the reflective film comprises an Al-based alloy containing at least one element selected from Si and Ge in an amount of 5 to 40 at. %.

Abstract: Provided is a read-only optical information recording medium (for instance, a dual-layer BD-ROM), which uses blue laser and is provided with a reflecting film which has sufficiently high reflectivity while ensuring optical transparency required in manufacture, has excellent reproduction stability when used for an optical information recording medium and has excellent durability. The read-only optical information recording medium includes a structure wherein a plurality of laminated layers of the reflecting film and the optical transparent layer are formed on a substrate, and reproduces information by means of blue laser. The reflecting film closest to the substrate among the reflecting films is substantially composed of an Al-based alloy containing 0.5-3.0 atm % of Ti, and has a film thickness of 10 nm or more but not more than 30 nm.

Abstract: A recording layer for an optical information recording medium, which has a high reflectance (initial reflectance) and excellent recording characteristics; an optical information recording medium comprising the recording layer; and a sputtering target useful for forming the recording layer. The recording layer for an optical information recording medium, on which recording is performed by irradiation of laser light, is characterized by containing indium (In) oxide and palladium (Pd) oxide which includes palladium monoxide and palladium dioxide. The recording layer for an optical information recording medium is also characterized in that the ratio of Pd atoms contained in the recording layer relative to the total of In atoms and Pd atoms contained therein is 6-60 atom %.