Single-crystal – oriented-crystal – and epitaxy growth processes; – Processes of growth from liquid or supercritical state – Having pulling during growth
Reexamination Certificate
2002-12-04
2004-11-02
Kunemund, Robert (Department: 1765)
Single-crystal, oriented-crystal, and epitaxy growth processes;
Processes of growth from liquid or supercritical state
Having pulling during growth
C117S013000, C117S023000, C117S950000, C117S035000
Reexamination Certificate
active
06811607
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a doped aluminum oxide crystalline material intended for optical data storage applications.
2. Description of the Prior Art
Various attempts have been made to design higher density data storage media for computer devices to replace conventional storage media such as magnetic disks, CD-ROMs, DVDs, etc. Many of the obstacles faced with respect to developing improved storage media have been associated with inadequate material properties. For example, photopolymers have been investigated for use in one-bit or holographic data storage. However, photopolymers exhibit strong dimensional shrinkage. Also, most photo-sensitive polymers may be used only as WROM media (write once, read many times) and the rewritable photopolymers are still unstable and show significant fatigue when write-read cycles are repeated many times. Even write-once fluorescent photopolymers show strong reduction of fluorescent output signal when read repeatedly. An additional problem with most photopolymers, as well as for photorefractive crystals, another potential material for volumetric one-bit recording, is the necessity of using a femto-second high peak power Ti-sapphire laser to achieve efficient two-photon absorption. This type of laser is big, expansive and suitable only for laboratory demonstration.
Therefore, there exists a need for better materials for making high density data storage devices.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a crystalline material that may be employed in a data storage method based on fundamentally very fast electronic processes vs. phase change transitions or photo-induced polymerization for well known techniques.
It is a further object of the present invention to provide a crystalline material that may be employed in a data storage method that is capable of achieving a write/read rate up to 1 Gbit per second.
It is yet another object of the present invention to provide a crystalline material that may be employed in a data storage method that provides the ability to perform parallel processing of multiple marks on the storage media for further increase of write/read rate.
It is yet another object of the present invention to provide a crystalline material that may be employed in a data storage method that provides high data storage density restricted only by diffraction limit and NA of the optical components
It is yet another object of the present invention to provide a crystalline material that may be employed in a data storage method that provides the possibility of multilevel data storage due to linearity of luminescent response within 7 decades.
It is yet another object of the present invention to provide a crystalline material that may be employed in a data storage method that only requires low laser light energies for writing and reading of information (pJ and nJ range).
It is yet another object of the present invention to provide a crystalline material that may be employed in a data storage method that provides extremely high temperature and time stability of stored data (tested in radiation dosimetric application).
It is yet another object of the present invention to provide a crystalline material that may be employed in a data storage method that provides no degradation of material performance after millions of write/read cycles.
According to a first broad aspect of the present invention, there is provided a crystalline material comprising: a base material comprising Al
2
O
3
; a first dopant comprising magnesium; and a second dopant comprising carbon, wherein the crystalline material includes a plurality of at least one type of oxygen vacancy defect.
According to a second broad aspect of the present invention, there is provided a crystalline material comprising Al
2
O
3
, wherein the crystalline material includes a plurality of oxygen vacancy defects.
According to a third broad aspect of the present invention, there is provided a crystalline material comprising Al
2
O
3
, wherein the crystalline material includes at least one color center having: an absorption in the region of 435±5 nm, an emission in the region of 520±5 nm and a 9±3 ns fluorescence lifetime.
According to a fourth broad aspect of the present invention, there is provided a crystalline material comprising Al
2
O
3
, wherein the crystalline material includes at least one color center having: an absorption in the region of 335±5 nm, an emission in the region of 750±5 nm and a 80±10 ns fluorescence lifetime.
According to a fifth broad aspect of the present invention, there is provided a crystalline material comprising: a base material comprising Al
2
O
3
; a first dopant comprising magnesium; and a second dopant comprising carbon, wherein the crystalline material includes at least one color center having: an absorption in the region of 435±5 nm, an emission in the region of 520±5 nm and a 9±3 ns fluorescence lifetime.
According to a sixth broad aspect of the invention, there is provided a crystalline material comprising: a base material comprising Al
2
O
3
; a first dopant comprising magnesium; and a second dopant comprising carbon, wherein the crystalline material includes at least one color center having: an absorption in the region of 335±5 nm, an emission in the region of 750±5 nm and a 80±10 ns lifetime.
According to a seventh broad aspect of the invention, there is provided a crystalline material comprising: a base material comprising Al
2
O
3
; a first dopant comprising magnesium; and a second dopant comprising carbon, wherein the crystalline material includes at least one color center having: an absorption in the region of 435±5 nm, an emission in the region of 520±5 nm and a 9±3 ns fluorescence lifetime and at least one color center having: an absorption in the region of 335±5 nm, an emission in the region of 750±5 nm and a 80±10 ns lifetime.
According to an eighth broad aspect of the invention, there is provided a crystalline material comprising: a base material comprising Al
2
O
3
; a first dopant comprising magnesium, a second dopant comprising carbon, and a third dopant comprising hydrogen, wherein the crystalline material includes at least one color center having: an absorption in the region of 435±5 nm, an emission in the region of 520±5 nm and a 9±3 ns fluorescence lifetime and at least one color center having: an absorption in the region of 335±5 nm, an emission in the region of 750±5 nm and a 80±10 ns lifetime.
According to a ninth broad aspect of the invention, there is provided a crystalline material comprising a base material comprising Al
2
O
3
and a dopant comprising Mg, wherein the crystalline material includes a plurality of aggregate oxygen vacancy defects.
According to a tenth broad aspect of the invention, there is provided a method for making a crystalline material comprising the steps of: (a) doping a base material comprising Al
2
O
3
with a first dopant comprising magnesium to form a doped material; and (b) crystallizing the doped material in highly reducing atmosphere in order to form the crystalline material, wherein the crystalline material includes a plurality of at least one type of oxygen vacancy defect.
Other objects and features of the present invention will be apparent from the following detailed description of the preferred embodiment.
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patent:
Jagtiani + Guttag
Kunemund Robert
Landauer, Inc.
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