# US 10,312,422 B2 · Light emitting devices with optical elements and bonding layers

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- Number: US 10,312,422 B2
- Document ID: US10312422B2
- Status: Granted
- Kind: B2
- Application number: 15/443,902
- Filed: 2017-02-27
- Published: 2017-10-19
- Granted: 2019-06-04
- Earliest claimed: 2000-09-12
- Assignees: Lumileds LLC
- Applicants: Lumileds LLC
- Inventors: Michael D. Camras; Michael R. Krames; Wayne L. Snyder; Frank M. Steranka; Robert C. Taber; John J. Uebbing; Douglas W. Pocius; Troy A. Trottier; Christopher H. Lowery; Gerd O. Mueller; Regina B. Mueller-Mach
- Web page: https://patentgrep.com/patent/US10312422B2

## CPC

- H10H 20/855: Optical field-shaping means, e.g. lenses
- H10H 20/825: containing nitrogen, e.g. GaN
- H10H 20/835: {Reflective materials}
- H10H 20/8512: {Wavelength conversion materials}
- H10H 20/857: Interconnections, e.g. lead-frames, bond wires or solder balls
- H10H 20/819: characterised by their shape, e.g. curved or truncated substrates
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS

## Abstract

Light emitting devices with improved light extraction efficiency are provided. The light emitting devices have a stack of layers including semiconductor layers comprising an active region. The stack is bonded to a transparent optical element.

## Claims

### Claim 1

A device comprising:
a light emitting diode (LED) die comprising semiconductor layers including an active region, the LED die having a first coefficient of thermal expansion; and
a discrete and premade transparent optical element comprising a substantially flat bottom surface directly bonded to a top surface of the LED die, the transparent optical element having a second coefficient of thermal expansion approximately equal to the first coefficient of thermal expansion.

### Claim 2 (depends on 1)

The device of claim 1 wherein the transparent optical element is selected from the group consisting of ZnS and ZnSe and the semiconductor layers comprise GaN.

### Claim 3 (depends on 1)

The device of claim 1 wherein the transparent optical element is selected from the group consisting of Weierstrass sphere, hemisphere, portion of a sphere less than a hemisphere, ellipsoid, portion of an ellipsoid, and Fresnel.

### Claim 4 (depends on 1)

The device of claim 1 wherein an index of refraction of the transparent optical element is graded.

### Claim 5

A device comprising:
a light emitting diode (LED) die comprising a top surface and semiconductor layers including an active region, the LED die having a first coefficient of thermal expansion; and
a discrete and premade transparent optical element comprising a substantially flat bottom surface, the transparent optical element having a second coefficient of thermal expansion approximately equal to the first coefficient of thermal expansion; and
a bonding layer disposed between the top surface of the LED die and the bottom surface of the transparent optical element.

### Claim 6 (depends on 5)

The device of claim 5 wherein:
the LED die comprises a metal contact;
an electrically conductive layer is disposed on a surface of the transparent optical element facing the LED die; and
the bonding layer is patterned to permit the metal contact to make electrical contact to the electrically conductive layer.

### Claim 7 (depends on 6)

The device of claim 6 wherein the electrically conductive layer is indium tin oxide.

### Claim 8 (depends on 5)

The device of claim 5 wherein the bonding layer is selected from the group consisting of ZnS and ZnSe and the semiconductor layers comprise GaN.

### Claim 9 (depends on 5)

The device of claim 5 wherein:
the transparent optical element has a refractive index nlens;
the bonding layer has a refractive index nbond;
a top layer of the LED die has a refractive index nLED; and
nLED≤nbond≤nlens.

### Claim 10 (depends on 5)

The device of claim 5 wherein:
the transparent optical element has a refractive index nlens;
the bonding layer has a refractive index nbond;
a top layer of the LED die has a refractive index nLED; and
nLED≤nlens≤nbond.

### Claim 11 (depends on 5)

The device of claim 5 wherein:
the transparent optical element has a refractive index nlens;
the bonding layer has a refractive index nbond;
a top layer of the LED die has a refractive index nLED; and
nbond≤nLED≤nlens.

### Claim 12 (depends on 5)

The device of claim 5 wherein:
the transparent optical element has a refractive index nlens;
the bonding layer has a refractive index nbond;
a top layer of the LED die has a refractive index nLED; and
nbond≤nlens≤nLED.

### Claim 13 (depends on 5)

The device of claim 5 wherein:
the transparent optical element has a refractive index nlens;
the bonding layer has a refractive index nbond;
a top layer of the LED die has a refractive index nLED; and
nlens≤nbond≤nLED.

### Claim 14 (depends on 5)

The device of claim 5 wherein:
the transparent optical element has a refractive index nlens;
the bonding layer has a refractive index nbond;
a top layer of the LED die has a refractive index nLED; and
nlens≤nLED≤nbond.

### Claim 15 (depends on 5)

The device of claim 5 wherein:
the transparent optical element has a refractive index nlens;
the bonding layer has a refractive index nbond;
a top layer of the LED die has a refractive index nLED; and
nlens=nLED=nbond.

### Claim 16

A device comprising:
a light emitting diode (LED) die comprising a top surface and semiconductor layers including an active region, the LED die having a top layer with a refractive index nLED; and
a discrete and premade transparent optical element comprising a substantially flat bottom surface directly bonded to a top surface of the LED die, the transparent optical element having a refractive index nlens, where nLED≤nlens.

### Claim 17 (depends on 16)

The device of claim 16 wherein the transparent optical element is selected from the group consisting of Weierstrass sphere, hemisphere, portion of a sphere less than a hemisphere, ellipsoid, portion of an ellipsoid, and Fresnel.

### Claim 18 (depends on 16)

The device of claim 16 wherein the transparent optical element is selected from the group consisting of ZnS and ZnSe and the semiconductor layers comprise GaN.

### Claim 19 (depends on 16)

The device of claim 16 further comprising luminescent material included in or on the transparent optical element.

### Claim 20 (depends on 19)

The device of claim 19, wherein the luminescent material comprises one of phosphor particles and quantum dots.

### Claim 21

A device comprising:
a light emitting diode (LED) die comprising a top surface and semiconductor layers including an active region, the LED die having a top layer with a refractive index nLED; and
a discrete and premade transparent optical element comprising a substantially flat bottom surface bonded to a top surface of the LED die, the transparent optical element having a refractive index nlens, where nLED≤lens; and
a bonding layer disposed between the top surface of the LED die and the bottom surface of the transparent optical element.

### Claim 22 (depends on 21)

The device of claim 21 wherein:
the LED die comprises a metal contact;
an electrically conductive layer is disposed on a surface of the transparent optical element facing the LED die; and
the bonding layer is patterned to permit the metal contact to make electrical contact to the electrically conductive layer.

### Claim 23 (depends on 22)

The device of claim 22 wherein the electrically conductive layer is indium tin oxide.

### Claim 24 (depends on 21)

The device of claim 21 wherein the bonding layer is selected from the group consisting of ZnS and ZnSe and the semiconductor layers comprise GaN.

### Claim 25 (depends on 21)

The device of claim 21 further comprising luminescent material included in the bonding layer.

### Claim 26 (depends on 25)

The device of claim 25, wherein the luminescent material comprises one of phosphor particles and quantum dots.