EP0047591A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Light emitting diodes with high external quantum efficiency
Assignee: Nortel Networks Ltd
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Filing: 1981-08-14
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Granted: —
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Expires: 2001-08-14
Abstract
Abstract A surface emitting light emitting diode (LED) has a reflecting element (24; 22) to redirect light emitted away from the light emitting region towards an exit window (30). The LED bottom contact (24) is formed over the reflecting element (24; 22) and a current confining path is set up within the LED-to funnell current between the top and bottom contacts (24; 28) around the reflecting (24; 22) element and through the light emitting region (32).
Inventors
- 👤 Anthony John Springthorpe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 22:21
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/80; H10H20/83; H10H20/831; H10H20/8312; H10H20/01; H10H20/011; H10H20/018; H10H20/81; H10H20/811; H10H20/822; H10H20/824; H10H20/84; H10H20/841; H10H20/819; H10H20/821; H10H20/832
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
148 words
A surface emitting light emitting diode comprising: a semiconductor substrate on which is grown a double heterostructure consisting of a first confining layer, an active layer, and a second confining layer; a transparent element on one side of the heterostructure permitting exit of light emitted from an emitting region of the active layer; the light emitting diode characterised by: a reflective element (22) on the other side of the heterostructure for reflecting emitted light towards the transparent element (30); the transparent element (30), the emitting region (32), and the reflective element (22) being substantially aligned; a first contact metallization (28) extending around the transparent element (30); a second contact metallization (24) extending around the reflective element (22); and current directing means (18; 16) causing current entering at one contact metallization to converge towards the emitting region and to diverge from the emitting region to the other contact metallization.
Claim 2
Dependent Claim
148 words
A surface emitting light emitting diode comprising: a semiconductor substrate on which is grown a double heterostructure consisting of a first confining layer, an active layer, and a second confining layer; a transparent element on one side of the heterostructure permitting exit of light emitted from an emitting region of the active layer; the light emitting diode characterised by: a reflective element (22) on the other side of the heterostructure for reflecting emitted light towards the transparent element (30); the transparent element (30), the emitting region (32), and the reflective element (22) being substantially aligned; a first contact metallization (28) extending around the transparent element (30); a second contact metallization (24) extending around the reflective element (22); and current directing means (18; 16) causing current entering at one contact metallization to converge towards the emitting region and to diverge from the emitting region to the other contact metallization.
Claim 3
Dependent Claim
26 words
A light emitting diode as claimed in claim 1 further characterised in that the transparent element (30) comprises a window in said first contact metallization (28).
Claim 4
Dependent Claim
25 words
A light emitting diode as claimed in claim 2 further characterised in that the transparent element (30) further comprises a well extending into the semiconductor.
Claim 5
Dependent Claim
42 words
A light emitting diode as claimed in claim 1, 2 or 3, further characterised in that the reflective element (22) comprises a layer of dielectric and a metal layer on a surface of the dielectric layer remote from the emitting region (32).
Claim 6
Dependent Claim
18 words
A light emitting diode as claimed in claim 4 further characterised in that the dielectric is silicon dioxide.
Claim 7
Dependent Claim
26 words
A light emitting diode as claimed in claim 4 further characterised in that the second contact metallization (24) forms a lateral extension of the metal layer.
Claim 8
Dependent Claim
23 words
A light emitting diode as claimed in claim 1, 2 or 3 further characterised in that the reflecting element is a multi-layer dielectric.
Claim 9
Dependent Claim
23 words
A light emitting diode as claimed in claim 7 further characterised in that the multi-layer dielectric includes alternating layers of alumina and silicon.
Claim 10
Dependent Claim
47 words
A light emitting diode as claimed in claim 1 further characterised in that a well (80) extends into the substrate, the well (80) being vertically aligned with the emitting region (76), the reflecting element (82; 84) comprising a reflective layer on a bottom surface of the well.
Claim 11
Dependent Claim
31 words
A light emitting diode as claimed in claim 9 further characterised in that the second contact metallization (84) is formed on an outer'surface of the substrate and extends around the well.
Claim 12
Dependent Claim
32 words
A light emitting diode as claimed in claim 9 or 10 further characterised in that the heterostructure is a GaAlAs heterostructure, the first confining layer being at least 25 microns in thickness.
Claim 13
Dependent Claim
30 words
A light emitting diode as claimed in claim 9, 10 or 11, further characterised in that a metal heat sink (86) extends into the well and contacts the reflecting layer.
Claim 14
Dependent Claim
117 words
A light emitting diode as claimed in claim 1, further characterised in that the current directing means is formed by an n-type barrier layer (18) formed on the second confining layer except at a central region thereof in vertical alignment with the emitting region (32), a p-type diffusion layer (20) extending into the barrier layer and into the second confining layer (16) at said central region, the junction of the barrier layer (18) and the second confining layer (16) forming, in operation, a reverse-biased isolating p-n junction, current thus being funneled along said p-type diffusion layer (20) and into the second confining layer (16) where the p-type diffusion layer (20) extends into the. second confining layer (16).
Claim 15
Dependent Claim
21 words
A light emitting diode as claimed in claim 13, further characterised in that the diode is formed as a GaAlAs heterostructure.
Claim 16
Dependent Claim
64 words
A light emitting diode as claimed in claim 1, further characterised in that the current directing means is formed by an annular region (38) within the first confining layer (42), said annular region (38) and the first confining layer (42) being oppositely doped whereby, in operation, to establish a reverse-biased junction at said annular region, which junction confines current to a central window (40).
Claim 17
Dependent Claim
29 words
A light emitting diode as claimed in claim 15, further characterised in that the first confining layer (42) is p-type InP and the annular region (38) is n-type InP.
Claim 18
Dependent Claim
25 words
A light emitting diode as claimed in claim 15 or 16, further characterised in that the second confining layer (46) is highly conductive n-type InP.
References Cited (Backward Citations)
No citation records indexed.
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