Optical recording medium exhibiting eutectic phase equilbria

• US 5,458,941 A
• Filed: 06/09/1994
• Issued: 10/17/1995
• Est. Priority Date: 06/09/1994
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Hintz, Michael B.
• Primary Examiner(s): Ryan, Patrick J.
• Assistant Examiner(s): MULVANEY, ELIZABETH EVANS
• Application Number:
  US08/257,076
• Time in Patent Office: 495 Days
• Field of Search: 428/64, 428/65, 428/457, 428/913, 430/270, 430/945, 346/76 L, 346/135.1, 369/288
• US Class Current: 428/64.4
• CPC Class Codes: G11B 2007/24306 transition metal elements of groups 3-10
• CPC Class Codes: G11B 2007/24308 transition metal elements of group 11 (Cu, Ag, Au)
• CPC Class Codes: G11B 2007/2431 group 13 elements (B, Al, Ga, In)
• CPC Class Codes: G11B 2007/24312 group 14 elements (e.g. Si, Ge, Sn)
• CPC Class Codes: G11B 2007/25708 containing group 13 elements (B, Al, Ga)
• CPC Class Codes: G11B 2007/2571 containing group 14 elements except carbon (Si, Ge, Sn, Pb)
• CPC Class Codes: G11B 2007/25715 containing oxygen
• CPC Class Codes: G11B 7/00557 involving phase-change media
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/243 comprising inorganic materials only, e.g. ablative layers
• CPC Class Codes: G11B 7/257 of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10S 430/146 Laser beam
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

A multilayer optical recording medium comprising a substrate, an optional dielectric layer, a first recording layer, a second recording layer, and an optional protective layer. The first recording layer comprises an alloy of a metal and at least one doping element, and the second recording layer comprises a semiconductor. A binary combination of the metal of the first recording layer and the semiconductor of the second recording layer exhibits eutectic phase equilibria.

Claims

1. An optical recording medium comprising, in order:

a transparent substrate;

a first recording layer comprising an alloy of a metal and at least one doping element; and

a second recording layer comprising a semiconductor, wherein a binary combination of the metal and the semiconductor exhibits eutectic phase equilibria.

2. The medium of claim 1, further comprising a protective layer on a side of the second recording layer opposite the substrate.

3. The medium of claim 1, further comprising a dielectric layer between the substrate and the first recording layer.

4. The medium of claim 3, wherein the dielectric layer comprises a material selected from the group consisting of aluminum oxide, silicon dioxide, and combinations thereof.

5. The medium of claim 1, wherein the alloy is selected from the group consisting of Al-Cr, Au-Co, and Al-Ti.

6. The medium of claim 5, wherein the alloy is Al-Cr.

7. The medium of claim 1, wherein the doping dement is present in sufficient quantity such that the sheet electrical conductance of the medium is less than 0.1 siemens.

8. The medium of claim 1, wherein the doping element is present in the alloy in the range from about 1 to about 12 atomic %.

9. The medium of claim 1, wherein the semiconductor is selected from the group consisting of Si, Ge, and combinations thereof.

10. The medium of claim 1, wherein the semiconductor is alloyed with at least one additional material, wherein the additional material is present in the range from 0 to 30 atomic %.

11. The medium of claim 9, wherein the semiconductor is Ge.

12. The medium of claim 1, wherein the flat surface reflectance (R) of the medium at 780 nm wavelength is in the range from 0.55 to 0.85.

13. An optical recording medium comprising, in order:

a transparent substrate;

a dielectric layer;

a first recording layer comprising an alloy of Al and Cr, wherein the Cr is present in a quantity between 2.5 and 4 atomic %;

a second recording layer comprising Ge; and

a protective layer.

14. An optical recording system comprising:

a medium, comprising, in order;

a transparent substrate;

a first recording layer comprising an alloy of a metal and at least one doping element;

a second recording layer comprising a semiconductor, wherein a binary combination of the metal and the semiconductor exhibits eutectic phase equilibria; and

a protective layer;

a focused laser beam positioned to enter the medium through the substrate, wherein the laser beam is capable of heating the first and second recording layers until localized melting and endothermic mixing of the two layers occur, thereby causing a recorded spot to be formed in the medium, wherein the recorded spot has a reflectance lower than the reflectance of the surrounding unrecorded regions; and

a photodetector positioned to detect the reflected laser beam exiting the medium.

15. The system of claim 14, wherein the alloy is Al-Cr.

16. The system of claim 14, wherein the doping element is present in sufficient quantity such that the sheet electrical conductance of the medium is less than 0.1 siemens.

17. The system of claim 14, wherein the semiconductor is Ge.

18. The system of claim 14, wherein the flat surface reflectance (R) of the medium at 780 nm wavelength is in the range from 0.55 to 0.85.

19. The system of claim 14, further comprising a dielectric layer between the substrate and the first recording layer.