# US 5,705,834 A · Increased efficiency LED

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- Number: US 5,705,834 A
- Document ID: US5705834A
- Status: Granted
- Kind: A
- Application number: 08/644,654
- Filed: 1996-04-23
- Granted: 1998-01-06
- Earliest claimed: 1996-04-23
- Assignees: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
- Inventors: Claudio O. Egalon; Robert S. Rogowski
- Web page: https://patentgrep.com/patent/US5705834A

## CPC

- H10H 20/819: characterised by their shape, e.g. curved or truncated substrates
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS

## Abstract

In an LED a large portion of the light produced is lost due to total internal reflection at the air-semiconductor interface. A reverse taper of the semiconductor is used to change the angle at which light strikes the interface so that a greater portion of the light is transmitted.

## Claims

### Claim 1

A light emitting diode comprising:
two semiconductor regions forming a light producing diode junction;
a light emitting end face;
a first one of the two semiconductor regions forming an outer volume, surrounding a second of the two semiconductor regions;
a base, opposed to the light emitting end face;
a plurality of sides of the outer volume, the sides connecting the light emitting end face to the base;
the sides further defining a reverse taper such that the cross sectional area of the light emitting diode is greater at the light emitting end face than at the base.

### Claim 2 (depends on 1)

A light emitting diode according to claim 1 wherein the sides are curved to produce a curved reverse taper.

### Claim 3 (depends on 1)

A light emitting diode according to claim 1 further comprising:
a layer having an index of refraction between that of the light emitting diode at the light emitting end face and that of a medium in which the light emitting diode is to be operated;
the layer directly optically connected to the light emitting end face.

### Claim 4 (depends on 3)

A light emitting diode according to claim 3 wherein the sides are curved to produce a curved reverse taper.

### Claim 5 (depends on 3)

A light emitting diode according to claim 3 wherein the layer is chosen to be of a shape such that it continues the reverse taper of the light emitting diode.