US3865646A
Expired / Lapsed
US
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Dielectric optical waveguides and technique for fabricating same
Assignee: AT&T Inc
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Filing: 1973-12-26
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Granted: 1975-02-11
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Expires: 1993-12-26
Abstract
Abstract A method of fabricating dielectric optical waveguides comprises the steps of: (1) fabricating a single or double heterostructure from the GaAs-AlGaAs system preferably by liquid phase epitaxy or molecular beam epitaxy; (2) forming a native oxide layer on the top surface of the heterostructure by anodization in H2O2; (3) removing a portion of the oxide layer to form a mask and hence to define the waveguide shape in the direction of light propagation; and (4) forming a mesa-like structure with optically flat side walls by etching at a slow rate in Br2-CH3OH. After step (4) two alternative techniques leading to structurally different waveguides may be followed. In one technique, an AlGaAs layer is epitaxially grown over the mesa to form a two dimensional waveguide. In the other technique, the edges of the active region of an AlGaAs double heterostructure are differentially etched in a neutral solution of H2O2. The latter step is particularly useful in the fabrication of active devices because the resulting structure is self-masking, thereby facilitating the formation of electrical contacts.
Inventors
- 👤 Ralph Andre Logan
- 👤 Bertram Schwartz
- 👤 Jr Joseph Charles Tracy
- 👤 William Wiegmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 00:43
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/10; G02B6/12; G02B6/13; G02B6/131; H; H01; H01S; H01S5/00; H01S5/20; H01S5/22; H10; H10H; H10H20/00; H10H20/01; H10H20/011; H10H20/013; Y; Y10; Y10S; Y10S148/00; Y10S148/049; Y10S148/051; Y10S148/056; Y10S148/065; Y10S148/067; Y10S148/072; Y10S148/118; Y10S148/145; Y10S438/00; Y10S438/911; Y10S438/942; Y10S438/945
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
174 words
A METHOD OF FABRICATING A DIELECTRIC WAVEGUIDE COMPRISING THE STEPS OF: A. EPITAXIALLY GROWING A GAAS-ALGAAS HETEROSTRUCTURE IN WHICH LIGHT IS TO BE GUIDED, B. FORMING A NATIVE OXIDE LAYER ON A MAJOR SURFACE OF SAID HETEROSTRUCTURE, C. REMOVING FROM SAID MAJOR SURFACE SELECTED PORTIONS OF SAID OXIDE LAYER THEREBY FORMING FROM THE REMAINING PORTIONS OF SAID OXIDE LAYER A MASK HAVING A PREDETERMINED SHAPE, D. FORMING A MESA FROM SAID HETEROSTRUCTURE BY BRINGING SAME INTO CONTACT WITH A BROMINE METHANOL SOLUTION CONTAINING APPROXIMATELY 0.05 TO 0.1 PERCENT BROMINE BY VOLUME, THEREBY ETCHING AWAY AT A RELATIVELY S;PW RATE THOSE PORTIONS OF SAID HETEROSTRUCTURE NOT COVERED BY SAID MASK, SAID SOLUTION BEING EFFECTIVE TO FORM OPTICALLY FLAT SURFACT ON OPPOSITE SIDE WALLS OF SAID MESA, AND E. BRINGING A SOLUTION OF ALGAAS INTO CONTACT WITH THE TOP SURFACE AND SIDE WALLS OF SAID MEANS AND GROWING THEREON BY LIQUID PHASE EPITAXY AN ALGAAS LAYER, SAID MASK FORMED FROM SAID NATIVE OXIDE LAYER SERVING TO PROTECT THE SURFACE THEREUNDER FROM BEING DISSOLVED IN SAID SOLUTION.
Claim 2
Independent Claim
174 words
A METHOD OF FABRICATING A DIELECTRIC WAVEGUIDE COMPRISING THE STEPS OF: A. EPITAXIALLY GROWING A GAAS-ALGAAS HETEROSTRUCTURE IN WHICH LIGHT IS TO BE GUIDED, B. FORMING A NATIVE OXIDE LAYER ON A MAJOR SURFACE OF SAID HETEROSTRUCTURE, C. REMOVING FROM SAID MAJOR SURFACE SELECTED PORTIONS OF SAID OXIDE LAYER THEREBY FORMING FROM THE REMAINING PORTIONS OF SAID OXIDE LAYER A MASK HAVING A PREDETERMINED SHAPE, D. FORMING A MESA FROM SAID HETEROSTRUCTURE BY BRINGING SAME INTO CONTACT WITH A BROMINE METHANOL SOLUTION CONTAINING APPROXIMATELY 0.05 TO 0.1 PERCENT BROMINE BY VOLUME, THEREBY ETCHING AWAY AT A RELATIVELY S;PW RATE THOSE PORTIONS OF SAID HETEROSTRUCTURE NOT COVERED BY SAID MASK, SAID SOLUTION BEING EFFECTIVE TO FORM OPTICALLY FLAT SURFACT ON OPPOSITE SIDE WALLS OF SAID MESA, AND E. BRINGING A SOLUTION OF ALGAAS INTO CONTACT WITH THE TOP SURFACE AND SIDE WALLS OF SAID MEANS AND GROWING THEREON BY LIQUID PHASE EPITAXY AN ALGAAS LAYER, SAID MASK FORMED FROM SAID NATIVE OXIDE LAYER SERVING TO PROTECT THE SURFACE THEREUNDER FROM BEING DISSOLVED IN SAID SOLUTION.
Claim 3
Dependent Claim
50 words
The method of claim 1 wherein said heterostructure is a single heterostructure which includes an AlxGa1 xAs layer, x > 0, and formed thereon an AlyGa1 yAs layer 0 < or = y < x, and wherein said AlGaAs layer grown by step (e) comprises AlqGa1 qAs, q > y.
Claim 4
Dependent Claim
53 words
The method of claim 1 wherein said heterostructure is a double heterostructure comprising an AlyGa1 yAs layere formed between and contiguous with layers of AlxGa1 xAs and AlzGa1 zAs, 0 < or = y < x and z, and wherein said AlGaAs layer grown by step (e) comprises AlqGa1 qAs, q > y.
Claim 5
Independent Claim
162 words
A method of fabricating a dielectric waveguide comprising the steps of: a. epitaxially growing a GaAs-AlGaAs heterostructure in which light is to be guided; b. forming a native oxide layer on a major surface of said heterostructure, c. removing from said major surface selected portions of said oxide layer thereby forming from the remaining portions of said oxide layer a mask having a predetermined shape; d. forming a mesa from said heterostructure by bringing same into contact with a bromine methanol solution containing approximately 0.05 to 0.1 percent bromine by volume, thereby etching away at a relatively slow rate those portions of said heterostructure not covered by said mask, said solution being effective to form optically flat surfaces on opposite side walls of said mesa, and e. removing said oxide mask from said heterostructure, thereby exposing a top major surface of said mesa, and growing by molecular beam epitaxy an AlGaAs layer on said surface and the side walls of said mesa.
Claim 6
Independent Claim
162 words
A method of fabricating a dielectric waveguide comprising the steps of: a. epitaxially growing a GaAs-AlGaAs heterostructure in which light is to be guided; b. forming a native oxide layer on a major surface of said heterostructure, c. removing from said major surface selected portions of said oxide layer thereby forming from the remaining portions of said oxide layer a mask having a predetermined shape; d. forming a mesa from said heterostructure by bringing same into contact with a bromine methanol solution containing approximately 0.05 to 0.1 percent bromine by volume, thereby etching away at a relatively slow rate those portions of said heterostructure not covered by said mask, said solution being effective to form optically flat surfaces on opposite side walls of said mesa, and e. removing said oxide mask from said heterostructure, thereby exposing a top major surface of said mesa, and growing by molecular beam epitaxy an AlGaAs layer on said surface and the side walls of said mesa.
Claim 7
Dependent Claim
73 words
The method of claim 4 wherein said heterostructure is epitaxially grown on a (100) surface of a GaAs substrate having its (011) cleavage plane perpendicular to the direction of light to be guided therein, and wherein said etching produces optically flat surfaces preferentially along (111) crystallographic planes, said (111) planes forming an angle of about 53* with the growth plane (100), thereby to prevent shadowing of said (111) planes from the molecular beam.
Claim 8
Dependent Claim
50 words
The method of claim 4 wherein said heterostructure is a single heterostructure which includes an AlxGa1 xAs layer, x > 0, and formed thereon an AlyGa1 yAs layer 0 < or = y < x, and wherein said AlGaAs layer grown by step (e) comprising AlqGa1 qAs, q > y.
Claim 9
Dependent Claim
48 words
The method of claim 6 including after said oxide removing step the additional step of: bringing said AlyGa1 yAs layer into contact with a solution of bromine methanol containing about 0.05 to 0.1 percent bromine for a time period effective to round off the edges of said layer.
Claim 10
Dependent Claim
54 words
The method of claim 4 wherein said heterostructure is a double heterostructure which includes an AlyGa1 yAs layer formed between said contiguous with layers of AlxGa1 xAs and AlzGa1 zAs, 0 < or = y < x and z, and wherein said AlGaAs layer grown by step (e) comprises AlqGa1 qAs, q > y.
Claim 11
Dependent Claim
48 words
The method of claim 8 including after said oxide removing step the additional step of: bringing said AlzGa1 zAs layer into contact with a solution of bromine methanol containing about 0.05 to 0.1 percent bromine for a time period effective to round off the edges of said layer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |