Patent EP0042484A2 successfully refreshed from Google Patents.
EP0042484A2
Expired / Lapsed
EP
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High radiance LED's
Assignee: Nortel Networks Ltd
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Filing: 1981-05-11
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Granted: —
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Expires: 2001-05-11
Abstract
Abstract In a surface emitting light emitting diode (LED), light propagating in the plane of an active pn junction region (16) is utilized by turning it into the surface emitting direction using a mirror inclined at 45° to the plane of the junction. To form the mirror, a passivating spot (34) is deposited on the semiconductor crystal and the semiconductor surface is anodized, the resulting oxide layer (22) being simultaneously etched away leaving, under a central region of the spot, a mesa (20) having a curved wall (33), the tangent to which is at 45° to the plane of the junction region (16) at its boundary. An acid is selected which both oxidizes the semiconductor and etches away the oxide (22) as it is produced, thereby permitting a continuous and clean process.
Inventors
- 👤 Anthony John Springthorpe
- 👤 Christopher Michael Look
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 18:03
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/80; H10H20/81; H10H20/819; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/617; H10H20/814
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
74 words
A light emitting diode of the surface emitting type having a pn light emitting planar junction region characterized in that said junction region is at least partly bounded by a reflected surface (33) inclined at substantially 45° to the plane of the junction region whereby light propagating in the plane of the junction region is internally reflected at said reflective surface (33) and subsequently propagates substantially in a surface emitting direction of the LED.
Claim 2
Dependent Claim
74 words
A light emitting diode of the surface emitting type having a pn light emitting planar junction region characterized in that said junction region is at least partly bounded by a reflected surface (33) inclined at substantially 45° to the plane of the junction region whereby light propagating in the plane of the junction region is internally reflected at said reflective surface (33) and subsequently propagates substantially in a surface emitting direction of the LED.
Claim 3
Dependent Claim
92 words
A light emitting diode as claimed in claim 1, further characterized in a semiconductor substrate (12), a first confining layer (14) overlying the substrate, an active layer (16) overlying the first confining layer, and a second confining layer (18) overlying the active layer; the pn junction formed at the junction between one of the confining layers and the active layer (16), the active layer (16), the second confining layer (18) and part at least of the first confining layer (14) forming a truncated conical mesa (20) tapering away from the substrate (12).
Claim 4
Dependent Claim
29 words
A light emitting diode as claimed in claim 1 or 2 further characterized in that the light emitting junction region is bounded totally by said inclined reflected surface (33).
Claim 5
Dependent Claim
24 words
A light emitting diode as claimed in any of claims 1 to 3 further characterized in that the light emitting junction region is circular.
Claim 6
Dependent Claim
59 words
A light emitting diode as claimed in any of claims 2 to 4 further characterized in that the mesa (20) has an insulating film (24) extending over its surface except at a central region of an outer surface of the second confining layer (18), said insulating film (24) and said central region having a contact film (27) extending thereover.
Claim 7
Dependent Claim
25 words
A 1ight ` emitting diode as claimed in claim 5 further characterized in that said contact film (27) has plated heatsink metallization (28) extending thereover.
Claim 8
Dependent Claim
45 words
A light emitting diode as claimed in any of claims 2 to 6 further characterized in that a recess (30) extends from an outer surface of the substrate (12) to the first confining layer (14), the recess (30) being substantially aligned with the mesa (20).
Claim 9
Independent Claim
69 words
A method of fabricating a surface emitting light emitting diode comprising:- masking a region at one surface of a semiconductor crystal having a planar light emitting junction extending therethrough parallel to the surface; and non-selectively etching the crystal around the masked region until a mesa (20) remains having a curved wall (33) inclined substantially at 45° to the plane of a junction at the boundary of the junction region.
Claim 10
Independent Claim
69 words
A method of fabricating a surface emitting light emitting diode comprising:- masking a region at one surface of a semiconductor crystal having a planar light emitting junction extending therethrough parallel to the surface; and non-selectively etching the crystal around the masked region until a mesa (20) remains having a curved wall (33) inclined substantially at 45° to the plane of a junction at the boundary of the junction region.
Claim 11
Dependent Claim
36 words
A method as claimed in claim 8 further characterized in that said non-selective etch is performed by anodizing exposed parts of the semiconductor crystal to produce an oxide surface layer (46), and then dissolving the oxide.
Claim 12
Dependent Claim
39 words
A method as claimed in claim 9 further characterized in that a common solution (44) functions both as an electrolyte in the anodization of the crystal surface and as an etchant in the dissolution of the oxide layer (46).
Claim 13
Dependent Claim
34 words
A method as claimed in claim 10 further characterized in that an anodizing voltage and solution strength are selected so that etching of said oxide layer (46) marginally lags anodization of the crystal surface.
Claim 14
Independent Claim
30 words
A method as claimed in claims 10 or 11 further characterized in that said common solution (44) is phosphoric acid solution having a pH in the range 1.5 to 3.5.
Claim 15
Independent Claim
43 words
A method as claimed in any of the preceding claims further characterized in depositing an insulating layer (24) over said mesa (20) except at a central region of the mesa top surface and vapour depositing a contact layer (27) over said central region.
Claim 16
Dependent Claim
21 words
A method as claimed in claim 13 further characterized in electro-plating a metallized heatsink layer (28) over said contact layer (27).
Claim 17
Independent Claim
30 words
A method as claimed in any of claims 9 to 14 further characterized in that a dc anodizing current is used to anodize the exposed parts of the semiconductor crystal.
Claim 18
Independent Claim
30 words
A method as claimed in any of claims 9 to 14 further characterized in that a pulsed anodizing current is used to anodize the exposed parts of the semiconductor crystal.
References Cited (Backward Citations)
No citation records indexed.
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