US3801966A
Expired / Lapsed
US
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Optical memory device
Assignee: Hitachi Ltd
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Filing: 1972-08-18
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Granted: 1974-04-02
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Expires: 1992-08-18
Abstract
Abstract An optical memory device comprising a compound film formed of two materials adjacent to each other; one material being such that its threshold voltage of current controlled differential negative resistance decreases with the light applied, and the other being an amorphous chalcogenide system. This amorphous chalcogenide system includes a substance selected from the group consisting of chalcogenide systems As-Te-Ge, Te-Ge-Sb-S, Te-Ge-SAs, Te-Ge-S-P, Te-Ge-Sb, Te-Ge-Sb-As, Se-Te-Ge, and S-Se-Te, and Zn-As. When a voltage is applied across said compound film, and a specific area of the compound film is irradiated by light, changes are introduced into the amorphous chalcogenide and thus a memory is fixed therein. The device is further characterized in that the material of which the threshold voltage of current controlled differential negative resistance decreases with the light applied, is a control material selected from the group consisting of CdS, CdSe, ZnSe, CdTe, SiO, Nb2O5, TiO2, SbSI, PbZrO3, NiO, VO2, Fe2O3 doped with 1-20% Cu, Fe3O4, MoO, TiO2, Cu2O, yttrium iron garnet doped with silicon Si and also the amorphous chalcogenide systems As-Te-Ge-S, As-Te-Ge-Si, and AsTe-Ge. Also, avalanche photodiode and light actuated silicon controlled rectifier (LASCR) having the same property can be used as the control materal.
Inventors
- 👤 M Terao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:28
CPC Classifications
G; G03; G03C; G03C1/00; G03C1/705; G11; G11C; G11C13/00; G11C13/0002; G11C13/0004; G11C13/0007; G11C13/04; G11C13/048; H; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/36; H01J29/39; H01J29/44; H01J31/00; H01J31/08; H01J31/58; H01J31/60; H10; H10N; H10N70/00; H10N70/20; H10N70/257; H10N70/801; H10N70/881; H10N70/882; H10N70/8825; H10N70/8828; G11C2213/00; G11C2213/30; G11C2213/32
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
73 words
An optical memory device in accordance with claim 1, in which said material of which the threshold voltage of current controlled differential negative resistance decreases with light irradiation is one selected from the group consisting of CdS, CdSe, ZnSe, CdTe, SiO, Nb2O5, TiO2, SbSI, PbZrO3, NiO, VO2, Fe2O3 doped with 1 to 20% of Cu, Fe3O4, MoO, TiO2, Cu2O, yttrium iron garnet doped with Si, and amorphous chalcogenide systems As-Te-Ge-S, As-Te-Ge-Si, and As-Te-Ge.
Claim 2
Dependent Claim
44 words
An optical memory device in accordance with claim 2, in which said amorphous chalcogenide system As-Te-Ge-S, has composition ranges of 10 to 50% of As, 10 to 50% of Te, 0.1 to 20% of Ge and 0.1 to 30% of S in atomic percentage.
Claim 3
Dependent Claim
44 words
An optical memory device in accordance with claim 2, in which said amorphous chalcogenide system As-Te-Ge-Si has composition ranges of 10 to 40% of As, 30 to 60% of Te, 5 to 20% of Ge and 5 to 20% of Si in atomic percentage.
Claim 4
Dependent Claim
39 words
An optical memory device in accordance with claim 2, in which said aMorphous chalcogenide system As-Te-Ge has composition ranges of 50 to 90% of As, 10 to 50% of Te and 0.1 to 10% of Ge in atomic percentage.
Claim 5
Dependent Claim
42 words
An optical memory device in accordance with claim 1 said amorphous chalcogenide material deposited on said first film is a substance selected from the group consisting of the amorphous chalcogenide systems As-Te-Ge, Te-Ge-Sb-S, Te-Ge-S-As, Te-Ge-S-P, Te-Ge-Sb, Te-Ge-Sb-As, Se-Te-Ge, and S-Se-Te, and Zn-As.
Claim 6
Dependent Claim
39 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system As-Te-Ge has composition ranges of 1 to 40% of Ge, 3 to 60% of As and 40 to 85% of Te in atomic percentage.
Claim 7
Dependent Claim
44 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system Te-Ge-Sb-S has composition ranges of 70 to 90% of Te, 5 to 20% of Ge, 1 to 5% of Sb, and 1 to 5% of S in atomic percentage.
Claim 8
Dependent Claim
44 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system Te-Ge-S-As has composition ranges of 70 to 90% of Te, 5 to 20% of Ge, 1 to 5% of As and 1 to 5% of S in atomic percentage.
Claim 9
Dependent Claim
44 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system Te-Ge-S-P has composition ranges of 70 to 90% of Te, 5 to 20% of Ge, 1 to 5% of S and 1 to 5% of P in atomic percentage.
Claim 10
Dependent Claim
39 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system Te-Ge-Sb has composition ranges of 70 to 90% of Te, 5 to 20% of Ge and 1 to 5% of Sb in atomic percentage.
Claim 11
Dependent Claim
44 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system Te-Ge-Sb-As has composition ranges of 70 to 90% of Te, 5 to 20% of Ge, 1 to 5% of Sb, and 1 to 5% of As in atomic percentage.
Claim 12
Dependent Claim
39 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system Se-As-Ge has composition ranges of 1 to 90% of Se, 1 to 60% of Ge, and 1 to 80% of As in atomic percentage.
Claim 13
Dependent Claim
39 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system Se-Te-Ge has composition ranges of 1 to 80% of Se, 10 to 90% of Te, and 1 to 50% of Ge in atomic percentage.
Claim 14
Dependent Claim
39 words
An optical memory device in accordance with claim 6, in which said amorphous chalcogenide system S-Se-Te has composition ranges of 1 to 80% of S, 10 to 90% of Se, and 1 to 80% of Te in atomic percentage.
Claim 15
Dependent Claim
31 words
An optical memory device in accordance with claim 6, in which said Zn-As has composition ranges of 40 to 80% of Zn, and 20 to 60% of As in atomic percentage.
Claim 16
Dependent Claim
97 words
An optical memory device in accordance with claim 1, wherein said second film of an amorphous chalcogenide has two states of optically different properties, and wherein said voltage applied by said means for applying a voltage between said two electrodes has a value so that electric current flows only at said specific area irradiated by said light beam, said two optically different states being retained independently of said voltage when said specific area is unirradiated by said light beam, and one of said states being transformed to the other by applying erasing voltage pulses between said electrodes.
Claim 17
Dependent Claim
23 words
An optical memory device in accordance with claim 1, wherein said means for applying a voltage between said two electrodes applies pulse voltages.
Claim 18
Dependent Claim
30 words
An optical memory device in accordance with claim 1, wherein said voltage and said light beam are simultaneously effected on the compound film formed of said first and second films.
Claim 19
Dependent Claim
23 words
An optical memory device in accordance with claim 1, wherein said means for irradiating a specific area produces a low intensity light beam.
Claim 20
Dependent Claim
27 words
An optical memory device in accordance with claim 20, in which said light beam is a laser light beam having a power of less than 5 mW.
Claim 21
Dependent Claim
21 words
An optical memory device in accordance with claim 21, in which said laser light beam has a power of 0.01 mW.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |