US5274249A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Superconducting field effect devices with thin channel layer
Assignee: University of Maryland, Baltimore
•
Filing: 1991-12-20
•
Granted: 1993-12-28
•
Expires: 2011-12-20
Abstract
Abstract A superconducting field effect device includes a substrate with an epitaxial superconducting film upon it and an insulating layer above a thinner region of the film which protects the film from the atmosphere and isolates it from a gate electrode which is on the insulating layer above a channel region of the thin film, and the epitaxial film has thicker regions suitable for contact to source and drain electrodes. Gate electrodes may be isolated from and oppose both sides of the superconducting thin regions so that enhanced modulation of a current in the thin region is provided. The invention provides high speed and high efficiency switches and modulators.
Inventors
- 👤 Xiaoxing Xi
- 👤 Chris Doughty
- 👤 Thirumalai Venkatesan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:39
CPC Classifications
H; H10; H10N; H10N60/00; H10N60/20; H10N60/205; H10N60/207; Y; Y10; Y10S; Y10S505/00; Y10S505/70; Y10S505/701; Y10S505/702
Claims Analysis
Total Claims: 52
Claim 1
Independent Claim
67 words
A superconducting device, comprising: a substrate; and a film of a superconducting material above the substrate and having a lower surface epitaxially connected thereto, the film having a thick region and a thin region which is thinner than said thick region, wherein the thin region has a thickness less than 20 times the coherence length of bulk material which comprises the same material as the superconducting film.
Claim 2
Dependent Claim
67 words
A superconducting device, comprising: a substrate; and a film of a superconducting material above the substrate and having a lower surface epitaxially connected thereto, the film having a thick region and a thin region which is thinner than said thick region, wherein the thin region has a thickness less than 20 times the coherence length of bulk material which comprises the same material as the superconducting film.
Claim 3
Dependent Claim
35 words
A device according to claim 1, wherein: said thin region has a thickness which is less than 15 times the coherence length of a bulk material which comprises the same material as the superconducting film.
Claim 4
Dependent Claim
34 words
A device according to claim 1, wherein: said thin region has a thickness which is less than 3 times the coherence length of a bulk material of the same material as the superconducting film.
Claim 5
Dependent Claim
18 words
A device according to claim 1, wherein: a thickness of the thin region is less than 200 angstroms.
Claim 6
Dependent Claim
18 words
A device according to claim 1, wherein: a thickness of the thin region is less than 50 angstroms.
Claim 7
Dependent Claim
18 words
A device according to claim 1, wherein: a thickness of the thin region is less than 10 angstroms.
Claim 8
Dependent Claim
25 words
A device according to claim 1, wherein: a thickness of the thick region is thick enough so that conventional ohmic contacts can be prepared thereon.
Claim 9
Dependent Claim
19 words
A device according to claim 1, wherein: a thickness of the thick region is at least 300 angstroms thick.
Claim 10
Dependent Claim
23 words
A device according to claim 1, further comprising: a buffer layer between and epitaxially contacted to both the thin region and the substrate.
Claim 11
Dependent Claim
71 words
A device according to claim 9, wherein: the buffer layer comprises at least one of the member of the group consisting of CeO 2 , MgO, nonsuperconducting YBa 2 Cu 3 O 7-x where x is between 0 and 1, nonsuperconducting (YPr)Ba 2 Cu 3 O 7-x where x is between 0 and 1, PrBa 2 Cu 3 O 7-x where x is between 0 and 1, and NdGaO 3 .
Claim 12
Dependent Claim
22 words
A device according to claim 9, wherein: the buffer layer comprises doped SrTiO 3 which is doped so that it is semiconducting.
Claim 13
Dependent Claim
13 words
A device according to claim 1, wherein: the substrate comprises SrTiO 3 .
Claim 14
Dependent Claim
15 words
A device according to claim 1, wherein: the substrate comprises semiconducting doped SrTiO 3 .
Claim 15
Dependent Claim
62 words
A device according to claim 1, wherein: the substrate comprises one of Si and GaAs, sapphire, fluorides, CeO 2 , MgO, NdGaO 3 , PrBaCuO 7-x where x is between 0 and 1, nonsuperconducting YBa 2 Cu 3 O 7-x where x is between 0 and 1 and nonsuperconducting (YPr)Ba 2 Cu 3 O 7-x where x is between 0 and 1.
Claim 16
Dependent Claim
14 words
A device structure to claim 1, wherein: the thin region comprises a metal-oxide superconductor.
Claim 17
Dependent Claim
23 words
A device according to claim 15, wherein: the metal-oxide superconductor is YBa 2 Cu 3 O 7-x where x between 0 and 1.
Claim 18
Dependent Claim
41 words
A device according to claim 1, wherein: the thin region comprises Pr 1-x Y x Ba 2 Cu 3 O 7-y for values of x and y that provide superconducting Pr 1-x Y x Ba 2 Cu 3 O 7-y .
Claim 19
Dependent Claim
121 words
A device according to claim 15, wherein: the metal-oxide superconductor is selected from a member of the group consisting of superconducting compounds that comprise elements from one of the following sets: the set consisting of Y R1 R2 O where R1 is at least one element selected from the set consisting of Ba, Sr and Ca, and R2 is at least one element selected from the set consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Cd, and the sets of Tl Ba Ca Cu O, Bi Sr Ca Cu O, Bi Pb Sr Ca Cu O, Bi K Cu O, La Sr Cu O, Cu O, Bi O, Ba K Bi O, and Ce Sr Cu O.
Claim 20
Dependent Claim
45 words
A device according to claim 1, further comprising: a high mobility layer between the epitaxially connected to the substrate and the thin film of superconducting material wherein the mobility of the high mobility layer at room temperature is at least 500 square centimeters per volt-second.
Claim 21
Dependent Claim
34 words
A device according to claim 19, wherein: the high mobility layer has strong proximity coupling to the thin region which is strong enough to increase a coherence length of the film of superconducting material.
Claim 22
Dependent Claim
22 words
A device according to claim 19, wherein: the high mobility layer comprises one of doped semiconducting SrTiO 3 , Si and GaAs.
Claim 23
Dependent Claim
67 words
A device according to claim 1, wherein: the substrate comprises one of Si and GaAs; and further comprising at least first and second buffer layers disposed between the substrate and the film of superconducting material, the first buffer layer having a lower surface epitaxially contacted to the silicon substrate and the second buffer layer having a second surface epitaxially contacted to the film of the superconducting material.
Claim 24
Dependent Claim
19 words
A device according to claim 1, further comprising: a passivating layer covering an upper surface of the thin region.
Claim 25
Dependent Claim
14 words
A device according to claim 23, wherein: the passivating layer comprises an insulating layer.
Claim 26
Dependent Claim
20 words
A device according to claim 23, wherein: the passivating layer is epitaxially contacted to the film of the thin region.
Claim 27
Dependent Claim
16 words
A device according to claim 23, wherein: the passivating layer comprises a perovskite type structure material.
Claim 28
Dependent Claim
19 words
A device according to claim 1, further comprising: a ferroelectric layer covering an upper surface of the thin region.
Claim 29
Dependent Claim
34 words
A device according to claim 27, wherein: the ferroelectric layer comprises at least one member selected from the group consisting of PLZT, PZT, (PbSrLaBaBi) (ZrTi)O 3 , (SrCaBaLiKPbTa) (NbMg)O 3 and (PbBaSr)TiO 3 .
Claim 30
Dependent Claim
18 words
A device according to claim 23, wherein: the passivating layer also covers a portion of the thicker region.
Claim 31
Dependent Claim
14 words
A device according to claim 23, wherein: the passivating layer comprises a pyroelectric layer.
Claim 32
Dependent Claim
16 words
A device according to claim 1, further comprising: a gate electrode opposed to the thin region.
Claim 33
Dependent Claim
113 words
A superconducting device, comprising: a first unit including a thin film of a superconducting material with an upper and a lower surface which forms a channel layer; an upper surface of a lower insulating gate layer epitaxially connected to the lower surface of the superconducting film and a lower surface of an upper insulating gate layer epitaxially connected to the upper surface of the superconducting film; a lower gate electrode below the lower insulating gate; an upper gate electrode above the upper insulating gate layer and; wherein the thickness of the thin film is less than 20 times the coherence length of a bulk material of the same material as the thin film.
Claim 34
Dependent Claim
113 words
A superconducting device, comprising: a first unit including a thin film of a superconducting material with an upper and a lower surface which forms a channel layer; an upper surface of a lower insulating gate layer epitaxially connected to the lower surface of the superconducting film and a lower surface of an upper insulating gate layer epitaxially connected to the upper surface of the superconducting film; a lower gate electrode below the lower insulating gate; an upper gate electrode above the upper insulating gate layer and; wherein the thickness of the thin film is less than 20 times the coherence length of a bulk material of the same material as the thin film.
Claim 35
Dependent Claim
21 words
A device according to claim 32, wherein: the gate electrode material is identical to the superconducting material of the thin film.
Claim 36
Dependent Claim
19 words
A device according to claim 32, wherein: all the layers of each unit are epitaxially connected to one another.
Claim 37
Dependent Claim
18 words
A device according to claim 32, wherein: a thickness of the channel layer is less than 150 angstroms.
Claim 38
Dependent Claim
16 words
A device according to claim 32, wherein: a gate electrode thickness is greater than 50 angstroms.
Claim 39
Dependent Claim
16 words
A device according to claim 32, wherein: a gate electrode thickness is less than 1000 angstroms.
Claim 40
Dependent Claim
14 words
A device according to claim 32, wherein: the channel layer comprises a metal-oxide superconductor.
Claim 41
Dependent Claim
87 words
A device according to claim 32, wherein: each gate layer comprises at least one material selected from the group consisting of CeO 2 , MgO, nonsuperconducting YBaCuO 7-x where x is between 0 and 1, nonsuperconducting (YPr)Ba 2 Cu 3 O 7-x where x is between 0 and 1, PrBa 2 Cu 3 O 7-x where x is between 0 and 1, SrTiO 3 , BaTiO 3 , LaAlO 3 , NdGaO 3 , PLZT, PZT, (PbSrLaBaBi) (ZrTi)O 3 , (SrCaBaLiKPbTa) (NbMg)O 3 and (PbBaSr)TiO 3 .
Claim 42
Dependent Claim
21 words
A device according to claim 32, wherein: a gate electrode comprises a material which lattice matches to the adjacent gate layer.
Claim 43
Dependent Claim
14 words
A device according to claim 32, wherein: a gate electrode comprises a metal-oxide superconductor.
Claim 44
Dependent Claim
29 words
A device according to claim 32, wherein: the channel layer and the gate electrode layer comprise elements from the group consisting of; Cu and O, and Bi and O.
Claim 45
Dependent Claim
43 words
A device according to claim 32, further comprising: units which are identical to the first unit and which are stacked upon one another so that the lower gate electrode of an upper unit is an upper gate electrode of an adjacent lower unit.
Claim 46
Dependent Claim
22 words
A device according to claim 43, further comprising: first electrical connecting means for electrically connecting at least two channel layers in parallel.
Claim 47
Dependent Claim
21 words
A device according to claim 43, further comprising: second electrical connection means for connecting at least two channel layers in series.
Claim 48
Dependent Claim
34 words
A device according to claim 43, further comprising: third electrical connecting means for electrically connecting at least two gate electrodes to a common voltage source, and wherein gate layers and channel layers form multilayers.
Claim 49
Dependent Claim
21 words
A device according to claim 43, wherein: all the layers are epitaxially contacted to the layers to which they are adjacent.
Claim 50
Dependent Claim
80 words
A device according to claim 44, wherein: said first electrical connecting means includes magnetic field reducing means for reducing magnetic fields generated in the structure by current flowing along the channels, by defining and electrically contacting the channels so that a direction of current in at least one of various portions of channels and in various channel layers is opposite, thereby producing from at least one of said various portions and said various channels, opposing magnetic fields which partially cancel.
Claim 51
Dependent Claim
55 words
A device according to claim 43, further comprising: a source and drain means, for conducting current in the channel layers; and wherein a channel layer is patterned to have an increased ratio of channel path length between the source and drain means to channel layer cross sectional, thereby increasing a resistance of said channel layer.
Claim 52
Dependent Claim
100 words
A device according to claim 32, wherein: the channel layer and the gate electrode layer comprise elements from the group consisting of; Tl Ba Ca Cu O, Bi Sr Ca Cu O, Bi Pb Sr Ca Cu O, Bi K Cu O, La Sr Cu O, Ba K Bi O, Ce Sr Cu O, and Y R1 R2 O where R1 is at least one element selected from the set consisting of Ba, Sr and Ca, and R2 is at least one element selected from the set consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Cd.
References Cited (Backward Citations)
US4489478A
Cited
US4843446A
Cited
US4692994A
Cited
EP0280308A2
Cited
JPS63241824A
Cited
JPS6411379A
Cited
JPS6417420A
Cited
JPS6419616A
Cited
JPS6424476A
Cited
EP0306896A2
Cited
US5019551A
Cited
JPS6472413A
Cited
WO1989003126A1
Cited
JPH01100812A
Cited
JPH02391A
Cited
WO1989006441A1
Cited
EP0324044A1
Cited
US5049543A
Cited
US5034374A
Cited
JPH0237786A
Cited
JPH02191382A
Cited
US5061971A
Cited
JPH0287688A
Cited
JPH0294678A
Cited
US5047390A
Cited
US5071832A
Cited
JPH02186682A
Cited
US5041188A
Cited
EP0390704A2
Cited
JPH02264485A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-12-27 | 1997-06-28 | 1997-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-27 | 2001-06-28 | 2001-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-27 | 2005-06-28 | 2005-12-28 | $7700.00 | Window Closed / Lapsed |