US5874147A
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Column III metal nitride films as phase change media for optical recording
Assignee: MediaTek Inc
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Filing: 1997-07-15
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Granted: 1999-02-23
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Expires: 2017-07-15
Abstract
Abstract This invention provides phase change media for optical storage based on semiconductors of nitrides of the column III metals. The surface of thin films of these wide bandgap semiconductors may be metallized (by desorption of the nitrogen) by irradiating with photons of energy equal to, or greater than the band gap of these materials, and with power densities beyond a critical threshold value. As a consequence of such writable metallization, these materials are excellent candidates for write once, read many times storage media since the differences in the reflectivity between the metal and its corresponding wide gap nitride are very large. Furthermore, once the nitrogen is desorbed, the written metallic phase can no longer revert back to the nitride phase and hence the media is stable and is truly a write-once system. Additional advantages offered by these materials over present day phase change media include higher differences in reflectivity contrast and suitability for use with short wavelength laser diodes (460 nm and lower) which are expected to be introduced into optical recording technology in the next 5 years. The band gap of alloys of nitrides of column III metals can be tuned by changing the relative fractions of the column III metals to continuously vary the band gap so as to be compatible with lasers having photon energies within the range. The low absorptivity and hence high transmissitivity, at the appropriate recording wavelength, of the starting phase also offers the potential application of these materials in a multiple-recording-layer format.
Inventors
- 👤 Nestor Alexander Bojarczuk, Jr.
- 👤 Supratik Guha
- 👤 Arunava Gupta
- 👤 Wade Wai-Chung Tang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:31
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/24018; G11B7/24027; G11B7/004; G11B7/0045; G11B7/00455; G11B7/005; G11B7/0052; G11B7/241; G11B7/242; G11B7/243; G11B7/252; G11B7/253; G11B7/26; G11B2007/24302; G11B2007/2431; G11B2007/24318; G11B2007/24322; G11B2007/25302; G11B2220/00; G11B2220/20; G11B2220/21; G11B2220/215; G11B2220/218; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10S430/00; Y10S430/146; Y10T; Y10T428/00; Y10T428/21
Claims Analysis
Total Claims: 50
Claim 1
Independent Claim
35 words
An optical recording medium consisting of a thin film of a metal nitride of composition MN situated on a substrate where M is a metal selected from the column III metals and N is nitrogen.
Claim 2
Dependent Claim
35 words
An optical recording medium consisting of a thin film of a metal nitride of composition MN situated on a substrate where M is a metal selected from the column III metals and N is nitrogen.
Claim 3
Dependent Claim
23 words
The optical recording medium according to claim 1 wherein M is a metal selected from the group consisting of aluminum, gallium, and indium.
Claim 4
Dependent Claim
13 words
The optical recording medium according to claim 1 wherein said substrate is sapphire.
Claim 5
Dependent Claim
49 words
An optical recording medium consisting of a thin film of a metal alloy of composition A x B y C 1-x-y N situated on a substrate where A, B and C are different column III metals, x and y are numbers between 0 and 1 and N is nitrogen.
Claim 6
Dependent Claim
49 words
An optical recording medium consisting of a thin film of a metal alloy of composition A x B y C 1-x-y N situated on a substrate where A, B and C are different column III metals, x and y are numbers between 0 and 1 and N is nitrogen.
Claim 7
Dependent Claim
19 words
The optical recording medium according to claim 4 wherein A is indium, B is gallium and C is aluminum.
Claim 8
Dependent Claim
13 words
The optical recording medium according to claim 4 wherein said substrate is sapphire.
Claim 9
Independent Claim
103 words
A system for the processing of information comprising: a) an optical recording medium consisting of a thin film of a metal nitride of composition MN situated upon a substrate where M is a metal selected from the column III metals and N is nitrogen; b) beam means for selectively irradiating regions of said medium to selectively convert discrete regions of said medium to the metal nitride to thereby form metallized regions of high reflectivity embedded in the metal nitride matrix, which metallized regions and matrix regions constitute encoded information; and c) means for scanning said beam means across the surface of said medium.
Claim 10
Independent Claim
103 words
A system for the processing of information comprising: a) an optical recording medium consisting of a thin film of a metal nitride of composition MN situated upon a substrate where M is a metal selected from the column III metals and N is nitrogen; b) beam means for selectively irradiating regions of said medium to selectively convert discrete regions of said medium to the metal nitride to thereby form metallized regions of high reflectivity embedded in the metal nitride matrix, which metallized regions and matrix regions constitute encoded information; and c) means for scanning said beam means across the surface of said medium.
Claim 11
Dependent Claim
13 words
The system of claim 7 wherein said irradiation produces a localized heating effect.
Claim 12
Dependent Claim
22 words
The system of claim 7 wherein the lateral dimensions of said metallized regions are comparable to the lateral dimensions of said beam.
Claim 13
Dependent Claim
12 words
The system of claim 7 wherein said beam means are a laser.
Claim 14
Dependent Claim
42 words
The system of claim 7 wherein the energy density of the beam for encoding is on the order of about 100 millijoules per square centimeter and the beam is delivered in a pulsed mode with a pulse time of a few nanoseconds.
Claim 15
Dependent Claim
21 words
The system of claim 11 wherein the diameter of the focussed beam is approximately equal to the wavelength of the beam.
Claim 16
Dependent Claim
21 words
The system of claim 10 wherein the wavelength of the beam is in the range of 200 nm to 650 nm.
Claim 17
Dependent Claim
35 words
The system of claim 10 wherein said laser used to encode said information emits light with a wavelength having an energy approximately equal to or larger than the band gap energy of the MN media.
Claim 18
Dependent Claim
24 words
The system of claim 7 wherein the thickness of the metal nitride layer is in the range of about 10 nm to 300 nm.
Claim 19
Dependent Claim
21 words
The system of claim 7 wherein the thickness of the metallized regions are less than or equal to about 200 nm.
Claim 20
Dependent Claim
16 words
The system of claim 7 wherein said beam means are also used to read said information.
Claim 21
Dependent Claim
47 words
The system of claim 17 wherein said beam means is a laser and said encoded information is read by rastering the beam from said laser across said medium and detecting the changes in reflectivity between the high reflectivity metallic regions and the low reflectivity metal nitride matrix.
Claim 22
Dependent Claim
14 words
the system of claim 7 further including additional beam means for reading said information.
Claim 23
Independent Claim
117 words
A system for the processing of information comprising: a) an optical recording medium consisting of a thin film of a metal alloy of composition A x B y C 1-x-y N situated upon a substrate where A, B and C are different column III metals, x and y are numbers between 0 and 1 and N is nitrogen; b) beam means for selectively irradiating regions of said medium to selectively convert discrete regions of said medium to the metal nitride to thereby form metallized regions of high reflectivity embedded in the metal nitride matrix, which metallized regions and matrix regions constitute encoded information; and c) means for scanning said beam means across the surface of said medium.
Claim 24
Independent Claim
117 words
A system for the processing of information comprising: a) an optical recording medium consisting of a thin film of a metal alloy of composition A x B y C 1-x-y N situated upon a substrate where A, B and C are different column III metals, x and y are numbers between 0 and 1 and N is nitrogen; b) beam means for selectively irradiating regions of said medium to selectively convert discrete regions of said medium to the metal nitride to thereby form metallized regions of high reflectivity embedded in the metal nitride matrix, which metallized regions and matrix regions constitute encoded information; and c) means for scanning said beam means across the surface of said medium.
Claim 25
Dependent Claim
13 words
The system of claim 20 wherein said irradiation produces a localized heating effect.
Claim 26
Dependent Claim
22 words
The system of claim 20 wherein the lateral dimensions of said metallized regions are comparable to the lateral dimensions of said beam.
Claim 27
Dependent Claim
12 words
The system of claim 20 wherein said beam means are a laser.
Claim 28
Dependent Claim
42 words
The system of claim 20 wherein the energy density of the beam required for encoding is on the order of 100 millijoules per square centimeter and the beam is delivered in a pulsed mode with a pulse time of a few nanoseconds.
Claim 29
Dependent Claim
20 words
The system of claim 24 wherein the diameter of the focussed beam is comparable to the wavelength of the beam.
Claim 30
Dependent Claim
21 words
The system of claim 23 wherein the wavelength of the light is in the range of 200 nm to 650 nm.
Claim 31
Dependent Claim
62 words
The system of claim 23 wherein said laser used to encode said information emits light with a wavelength from 200 nm to 650 nm and the gallium, aluminum, and indium composition of the recording medium adjusted so that the AI x Ga y In 1-x-y N medium has a band gap that is approximately equal to the photon energy of the laser.
Claim 32
Dependent Claim
24 words
The system of claim 20 where the thickness of the metal nitride layer is in the range of about 10 nm to 300 nm.
Claim 33
Dependent Claim
21 words
The system of claim 20 where the thickness of the metallized regions are less than or equal to about 200 nm.
Claim 34
Dependent Claim
16 words
The system of claim 20 wherein said beam means are also used to read said information.
Claim 35
Dependent Claim
46 words
The system of claim 30 wherein said beam means is a laser and said stored information is read by rastering the beam from said laser across said medium and detecting the changes in reflectivity between the high reflectivity metal spots and the low reflectivity metal nitride.
Claim 36
Dependent Claim
14 words
The system of claim 20 further including additional beam means for reading said information.
Claim 37
Dependent Claim
41 words
A multiple-layer optical recording disk comprising a plurality of layers of an optical recording medium of a thin film of a metal nitride of composition MN where M is a metal selected from the column III metals and N is nitrogen.
Claim 38
Dependent Claim
41 words
A multiple-layer optical recording disk comprising a plurality of layers of an optical recording medium of a thin film of a metal nitride of composition MN where M is a metal selected from the column III metals and N is nitrogen.
Claim 39
Dependent Claim
24 words
The disk of claim 33 wherein each layer is situated on a substrate and said layer/substrate pairs are stacked with an air gap inbetween.
Claim 40
Dependent Claim
26 words
The disk of claim 33 wherein each layer is situated on a substrate and said layer/substrate pairs are stacked with a layer of transmissive glue inbetween.
Claim 41
Dependent Claim
29 words
The disk of claim 33 wherein a first layer is situated on a substrate and each subsequent layer is stacked thereupon with a layer of a transmissive material inbetween.
Claim 42
Dependent Claim
18 words
The disk of claim 36 further including a final layer of a protective material on the topmost layer.
Claim 43
Dependent Claim
16 words
The disk of claim 33 wherein each layer of optical recording medium has a different composition.
Claim 44
Dependent Claim
55 words
A multiple-layer optical recording disk comprising a plurality of layers of an optical recording medium of a thin film of a metal alloy of composition A x B y C 1-x-y N where A, B and C are different column III metals, x and y are numbers between 0 and 1 and N is nitrogen.
Claim 45
Dependent Claim
55 words
A multiple-layer optical recording disk comprising a plurality of layers of an optical recording medium of a thin film of a metal alloy of composition A x B y C 1-x-y N where A, B and C are different column III metals, x and y are numbers between 0 and 1 and N is nitrogen.
Claim 46
Dependent Claim
24 words
The disk of claim 39 wherein each layer is situated on a substrate and said layer/substrate pairs are stacked with an air gap inbetween.
Claim 47
Dependent Claim
26 words
The disk of claim 39 wherein each layer is situated on a substrate and said layer/substrate pairs are stacked with a layer of transmissive glue inbetween.
Claim 48
Dependent Claim
29 words
The disk of claim 39 wherein a first layer is situated on a substrate and each subsequent layer is stacked thereupon with a layer of a transmissive material inbetween.
Claim 49
Dependent Claim
18 words
The disk of claim 42 further including a final layer of a protective material on the topmost layer.
Claim 50
Dependent Claim
16 words
The disk of claim 39 wherein each layer of optical recording medium has a different composition.
References Cited (Backward Citations)
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