Patent US4550411A successfully refreshed from Google Patents.
US4550411A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sources used in molecular beam epitaxy
Assignee: Thermo Fisher Scientific Inc
•
Filing: 1983-06-09
•
Granted: 1985-10-29
•
Expires: 2003-06-09
Abstract
Abstract A molecular or atomic beam source for use in molecular beam epitaxy comprises a hollow cylindrical crucible, preferably made of boron nitride, which is heated by an electric current passed through a plurality of very thin elongate metal strips disposed outside of and spaced apart from said crucible and mounted parallel to its axis. In order to maintain the strips in the correct position irrespective of temperature, they may be mounted on springs at each end, but preferably they are made in self supporting pairs linked at the open end of the crucible and mounted on brackets at the other end. The thin strips can be made self supporting by folding along lines parallel to their long axis in a variety of ways. They are arranged to present a large surface area to the crucible which ensures efficient heating and increases the maximum operating temperature of the source. The links between strips at the open end of the crucible can be made from the same material as the strips so that they provide additional heat at the open end of the crucible. This allows the crucible to be operated at higher temperatures than conventional sources and permits higher intensity molecular beams to be produced with true Knusden type evaporation. Therefore the source can also be used to produce beams from high melting point materials such as iron and silicon, as well as more usual materials such as galium, arsenic and phosphorus.
Inventors
- 👤 Paul R. Stonestreet
- 👤 David Williams
- 👤 Kenneth Anderson
- 👤 Peter J. L. Butcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:16
CPC Classifications
C; C30; C30B; C30B23/00; C30B23/02; C30B23/06; C30B23/066
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
156 words
A molecular or atomic beam source for molecular beam epitaxy comprising a hollow crucible having an open end and a closed end, at least one substantially self-supporting heating element heating said crucible disposed outside of and spaced apart from said crucible, and electrical supply leads to enable electrical current to be passed through each heating element, each heating element being supported by means of insulated electrically conductive supporting means only at the closed end of said crucible, each heating element comprising at least one pair of thin elongate metal strips extending substantially parallel to the axis of said crucible and disposed to present a major surface to the wall of said crucible, the strips of each pair being connected at the open end of said crucible by an electrically conductive link, and each of said strips being folded along one or more lines parallel to its longest edge in order to increase its resistance to bending.
Claim 2
Dependent Claim
156 words
A molecular or atomic beam source for molecular beam epitaxy comprising a hollow crucible having an open end and a closed end, at least one substantially self-supporting heating element heating said crucible disposed outside of and spaced apart from said crucible, and electrical supply leads to enable electrical current to be passed through each heating element, each heating element being supported by means of insulated electrically conductive supporting means only at the closed end of said crucible, each heating element comprising at least one pair of thin elongate metal strips extending substantially parallel to the axis of said crucible and disposed to present a major surface to the wall of said crucible, the strips of each pair being connected at the open end of said crucible by an electrically conductive link, and each of said strips being folded along one or more lines parallel to its longest edge in order to increase its resistance to bending.
Claim 3
Dependent Claim
33 words
A molecular or atomic beam source according to claim 1 in which said conductive link is capable of emitting heat, whereby the heat input to said open end of said crucible is increased.
Claim 4
Dependent Claim
19 words
A molecular or atomic beam source according to claim 1 in which said strips are of a refractor metal.
Claim 5
Dependent Claim
17 words
A molecular or atomic beam source according to claim 3 in which said strips are of tantalum.
Claim 6
Dependent Claim
28 words
A molecular or atomic beam source according to claim 2 in which the strips and conductive links comprising each said element are integrally formed from a refractory metal.
Claim 7
Dependent Claim
17 words
A molecular or atomic beam source according to claim 5 in which said refractory metal is tantalum.
Claim 8
Dependent Claim
38 words
A molecular or atomic beam source according to claim 1 in which each said thin elongate metal strip has a width much greater than its thickness and is folded along one line substantially parallel to its longest edge.
Claim 9
Dependent Claim
63 words
A molecular or atomic beam source according to claim 1 in which each said thin elongate metal strip has a width much greater than its thickness and is folded along two or more lines substantially parallel to its longest edge, and in which adjacent folds are made in opposite directions to produce a corrugated strip of overall width greater than its overall thickness.
Claim 10
Dependent Claim
59 words
A molecular or atomic beam source according to claim 1 in which each said thin elongate metal strip has a width much greater than its thickness and is folded along two or more lines substantially parallel to its longest edge, and in which adjacent folds are made in the same direction to produce a strip of substantially tubular form.
Claim 11
Dependent Claim
30 words
A molecular or atomic beam source according to claim 1 in which said crucible is provided at its open end with a narrow orifice whereby Knusden evaporation may be produced.
Claim 12
Dependent Claim
95 words
A molecular or atomic beam source according to claim 1 in which one heating element is provided, the said element comprising a plurality of strips spaced apart substantially equally, disposed substantially symmetrically around said crucible, and linked at opposite ends to adjacent strips by conductive links, said element and said conductive links being fabricated from a single sheet of refractory metal and mounted on supporting brackets attached to said element only at the closed end of said crucible, and said element being corrugated by folding along lines parallel to the longest axes of said strips.
Claim 13
Dependent Claim
36 words
A molecular or atomic beam source according to claim 1 in which at least a part of said supporting means is fabricated with a cross section and shape complementary to that of said strip supported therefrom.
References Cited (Backward Citations)
US2896004A
Cited
US3108171A
Cited
GB1270550A
Cited
US3726984A
Cited
GB1336910A
Cited
GB1381809A
Cited
GB1469978A
Cited
GB1515517A
Cited
GB2012818A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-28 | 1989-04-29 | 1989-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-28 | 1993-04-29 | 1993-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-28 | 1997-04-29 | 1997-10-29 | $7700.00 | Window Closed / Lapsed |