US5161149A
Expired / Lapsed
US
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Electron density storage device and method using STM
Assignee: Johns Hopkins University
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Filing: 1991-07-22
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Granted: 1992-11-03
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Expires: 2011-07-22
Abstract
Abstract The invention is a method and device providing very high density information storage on an organometallic charge transfer data storage medium. The medium is switched from one state to another through the application of an electric field to the medium by the probe tip of a scanning tunneling microscope resulting in an observable change in the electron density of the surface of the medium. A STM tip is used to write, read and erase data via the organometallic charge transfer medium (e.g. TCNQ, or derivatives thereof).
Inventors
- 👤 Richard S. Potember
- 👤 Shoji Yamaguchi
- 👤 Carla A. Viands
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:30
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/0002; G11C13/0009; G11C13/0014; B; B82; B82Y; B82Y10/00; G11B; G11B9/00; G11B9/12; G11B9/14; G11B9/1463; G11B9/149; Y; Y10; Y10S; Y10S430/00; Y10S430/143; Y10S977/00; Y10S977/902; Y10S977/932; Y10S977/943; Y10S977/947
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
171 words
A method for writing, reading and erasing data bits in an information storage device comprising: providing a data storage medium comprising a substrate and a film of organometallic charge transfer complex material thereon, said film having a thickness and a flat surface provided with a smooth topography, said film having a threshold field strength; writing a data bit by apply a first electric field to a very small localized portion of the surface of the film, said field exceeding the threshold field strength for the film and changing the electron density of the localized portion of the film; reading the data bit with a scanning tunneling microscope applying a second electric field less than the threshold field strength for the film to detect the change in electron density of the localized portion; erasing the data bit by applying a third electric field to the localized portion, said third field having the opposite polarity from the first field applied for writing and an intensity equal to the intensity of the first field.
Claim 2
Independent Claim
171 words
A method for writing, reading and erasing data bits in an information storage device comprising: providing a data storage medium comprising a substrate and a film of organometallic charge transfer complex material thereon, said film having a thickness and a flat surface provided with a smooth topography, said film having a threshold field strength; writing a data bit by apply a first electric field to a very small localized portion of the surface of the film, said field exceeding the threshold field strength for the film and changing the electron density of the localized portion of the film; reading the data bit with a scanning tunneling microscope applying a second electric field less than the threshold field strength for the film to detect the change in electron density of the localized portion; erasing the data bit by applying a third electric field to the localized portion, said third field having the opposite polarity from the first field applied for writing and an intensity equal to the intensity of the first field.
Claim 3
Dependent Claim
23 words
A method according to claim 1, wherein the change in electron density causes a change in the topography of the charge transfer film.
Claim 4
Dependent Claim
25 words
A method according to claim 1, wherein the electron density change produces a high contrast spot on the surface of the change transfer complex material.
Claim 5
Dependent Claim
21 words
A method according to claim 1, wherein the applied erasing field returns the change transfer complex material to its original state.
Claim 6
Dependent Claim
44 words
A method according to claim 1, wherein the electric fields for writing, reading and erasing are each created by a voltage pulse applied through a probe for the scanning tunneling microscope, said probe located at a gap distance from the surface of the film.
Claim 7
Dependent Claim
36 words
A method according to claim 5, including calculating the first and third electric fields by dividing the voltage applied through the probe tip by a sum of the thickness of the film plus the gap distance.
Claim 8
Dependent Claim
72 words
A method according to claim 1, wherein the charge transfer complex is a metal complexed with one of tetracyanoquinodimethane (TCNQ), tetracyanaphthoquinodimethane (TNAP), tetracyanoethylene (TCNE), dichlorodicyanobenzoquinone (DDQ) and derivatives of TCNQ selected from the group consisting of: TCNQ(OMe) TCNQ(OMe) 2 TCNQ(OMe)(OEt) TCNQ(OMe)(O-i-Pr) TCNQ(OMe)(O-i-Bu) TCNQ(O-i-C 2 H 5 ) TCNQ(OEt)(SMe) TCNQ Cl TCNQ Br TCNQ ClMe TCNQ BrMe TCNQ IMe TCNQ I TCNQ(OMe)(OCH 3 ) 2 TCNQ(CN) 2 TCNQ(Me) TCNQ(Et) TCNQ(i-Pr) TCNQ(i-Pr) 2 .
Claim 9
Dependent Claim
30 words
A method according to claim 7, wherein the metal is selected from the group consisting of silver, copper, nickel, cobalt, iron, magnesium, zinc, cadmium, platinum, iridium, palladium, osmium and rhodium.
Claim 10
Dependent Claim
14 words
A method according to claim 1, wherein the charge transfer complex is silver TCNQ.
Claim 11
Dependent Claim
14 words
A method according to claim 1, wherein the charge transfer complex is copper TCNQ.
Claim 12
Dependent Claim
15 words
A method according to claim 1, wherein the substrate is highly oriented pyrolitic graphite (HOPG).
Claim 13
Dependent Claim
69 words
A method according to claim 1, wherein the substrate is a conductive or semiconductive metal dichalcogenide having a formula MX 2 wherein M is a metal selected from the group consisting of Mo, W, Ta, Nb, Sn, Ti, Zr, Re, In, Pt, Hf, V, Mn, Fe, Rh, Ir, Ni, Pd, Co, Tc and Pb and X is a chalcogenide selected from the group consisting of S, Se and Te.
Claim 14
Dependent Claim
13 words
A method according to claim 1, wherein the substrate is a semiconductor wafer.
Claim 15
Dependent Claim
54 words
A method according to claim 1, wherein the substrate is a metal film deposited on a flat insulating material and further wherein the metal is one of Au, Ag, Pt, Rh, Pd, Ir, Cu and Ni and the flat material is one of mica, NaCl, KCl, KBr, CaF 2 , quartz, sapphire and glass.
Claim 16
Dependent Claim
18 words
A method according to claim 1, wherein the substrate is a film of Ag on a mica material.
Claim 17
Dependent Claim
35 words
A method according to claim 1, wherein the threshold field strength is in the range of 10 3 -10 4 V/cm, and the writing field is in the range of 10 4 -10 6 V/cm.
Claim 18
Dependent Claim
24 words
A method according to claim 1, wherein the data storage medium comprises a 2000 Angstrom thick film of copper TCNQ on an HOPG substrate.
Claim 19
Dependent Claim
21 words
A method according to claim 1, wherein the data storage medium is prepared according to a solid state vacuum deposition process.
Claim 20
Dependent Claim
15 words
A method according to claim 1, wherein the substrate is a mechanically polished metal crystal.
Claim 21
Independent Claim
150 words
A device for writing, reading and erasing data bits in an information storage device comprising: a storage medium comprising a substrate and a film of organometallic charge transfer complex material thereon, said film having a flat surface; scanning tunneling microscope means for applying a first electric field to the surface of the medium which is greater than a threshold field strength of the film, so that information is written on the medium; said scanning tunneling microscope means also including: a) means for reading the information; and b) means for applying a second electric field to the surface of the medium so that the information is erased; wherein the second electric field has an intensity equal to the first electric field but a polarity opposite the polarity of the first electric field; and field generating means for generating the first and second fields in accordance with a thickness of the film.
Claim 22
Independent Claim
150 words
A device for writing, reading and erasing data bits in an information storage device comprising: a storage medium comprising a substrate and a film of organometallic charge transfer complex material thereon, said film having a flat surface; scanning tunneling microscope means for applying a first electric field to the surface of the medium which is greater than a threshold field strength of the film, so that information is written on the medium; said scanning tunneling microscope means also including: a) means for reading the information; and b) means for applying a second electric field to the surface of the medium so that the information is erased; wherein the second electric field has an intensity equal to the first electric field but a polarity opposite the polarity of the first electric field; and field generating means for generating the first and second fields in accordance with a thickness of the film.
Claim 23
Dependent Claim
72 words
A device according to claim 20, wherein the charge transfer complex is a metal complexed with one of tetracyanoquinodimethane (TCNQ), tetracyanaphthoquinodimethane (TNAP), tetracyanoethylene (TCNE), dichlorodicyanobenzoquinone (DDQ) and derivatives of TCNQ selected from the group consisting of: TCNQ(OMe) TCNQ(OMe) 2 TCNQ(OMe)(OEt) TCNQ(OMe)(O-i-Pr) TCNQ(OMe)(O-i-Bu) TCNQ(O-i-C 2 H 5 ) TCNQ(OEt)(SMe) TCNQ Cl TCNQ Br TCNQ ClMe TCNQ BrMe TCNQ IMe TCNQ I TCNQ(OMe)(OCH 3 ) 2 TCNQ(CN) 2 TCNQ(Me) TCNQ(Et) TCNQ(i-Pr) TCNQ(i-Pr) 2 .
Claim 24
Dependent Claim
30 words
A device according to claim 21, wherein the metal is selected from the group consisting of silver, copper, nickel, cobalt, iron, magnesium, zinc, cadmium, platinum, iridium, palladium, osmium and rhodium.
Claim 25
Dependent Claim
14 words
A device according to claim 20, wherein the charge transfer complex is silver TCNQ.
Claim 26
Dependent Claim
14 words
A device according to claim 20, wherein the charge transfer complex is copper TCNQ.
Claim 27
Dependent Claim
15 words
A device according to claim 20, wherein the substrate is highly oriented pyrolitic graphite (HOPG).
Claim 28
Dependent Claim
71 words
A device according to claim 20, wherein the substrate is one of a conductive and a semiconductive metal dichalcogenide having a formula MX 2 wherein M is a metal selected from the group consisting of Mo, W, Ta, Nb, Sn, Ti, Zr, Re, In, Pt, Hf, V, Mn, Fe, Rh, Ir, Ni, Pd, Co, Tc and Pb and X is chalcogenide selected from the group consisting of S, Se and Te.
Claim 29
Dependent Claim
13 words
A device according to claim 20, wherein the substrate is a semiconductor wafer.
Claim 30
Dependent Claim
52 words
A device according to claim 20, wherein the substrate is a metal film deposited on a flat insulating material and further wherein the metal is one of Au, Ag, Pt, Rh, Cu and Ni and the flat material is one of mica, NaCl, KCl, KBr, CaF 2 , quartz, sapphire and glass.
Claim 31
Dependent Claim
18 words
A device according to claim 20, wherein the substrate is a film of Ag on a mica material.
Claim 32
Dependent Claim
15 words
A device according to claim 20, wherein the substrate is a mechanically polished metal crystal.
Claim 33
Dependent Claim
26 words
A device according to claim 20, wherein the change in electron density is detected by the scanning tunneling microscope means operating in the constant height mode.
Claim 34
Dependent Claim
26 words
A device according to claim 20, wherein the change in electron density is detected by the scanning tunneling microscope means operating in the constant current mode.
Claim 35
Dependent Claim
25 words
A method according to claim 1, wherein the change in electron density is detected by the scanning tunneling microscope operating in the constant height mode.
Claim 36
Dependent Claim
25 words
A method according to claim 1, wherein the change in electron density is detected by the scanning tunneling microscope operating in the constant current mode.
Claim 37
Dependent Claim
20 words
A method according to claim 1, wherein the data storage medium has a thickness in the range of 10-10,000 angstroms.
Claim 38
Dependent Claim
20 words
A method according to claim 1, wherein the data storage medium has a thickness in the range of 500-5000 angstroms.
Claim 39
Independent Claim
190 words
A method for writing, reading and erasing data bits in an information storage device comprising: providing a data storage medium comprising a highly oriented pyrolitic graphite (HOPG) substrate with a film of organometallic charge transfer complex material thereon, said film having a thickness and a surface provided with a smooth topography, said film having a threshold field strength; writing a data bit by applying a first electric field to a very small localized portion of the surface of the film, said field exceeding the threshold field strength for the film and changing the electron density of the localized portion of the film; reading the data bit with a scanning tunneling microscope applying a second electric field less than the threshold field strength for the film to detect the change in electron density of the localized portion; erasing the data bit by applying a third electric field to the localized portion, said third field having the opposite polarity from the first field applied for writing and said third and first fields having equal intensities; and calculating said first and third fields in accordance with a thickness of the organometallic charge complex.
Claim 40
Independent Claim
190 words
A method for writing, reading and erasing data bits in an information storage device comprising: providing a data storage medium comprising a highly oriented pyrolitic graphite (HOPG) substrate with a film of organometallic charge transfer complex material thereon, said film having a thickness and a surface provided with a smooth topography, said film having a threshold field strength; writing a data bit by applying a first electric field to a very small localized portion of the surface of the film, said field exceeding the threshold field strength for the film and changing the electron density of the localized portion of the film; reading the data bit with a scanning tunneling microscope applying a second electric field less than the threshold field strength for the film to detect the change in electron density of the localized portion; erasing the data bit by applying a third electric field to the localized portion, said third field having the opposite polarity from the first field applied for writing and said third and first fields having equal intensities; and calculating said first and third fields in accordance with a thickness of the organometallic charge complex.
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