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Relecura Inc.

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[email protected] September 2014

Tracking it’s evolution

Relecura IP Intelligence Report

Blue LED Technology

November, 2014

http://www.relecura.com/

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Highlights

• The Nobel Prize in physics for 2014 has been awarded to three eminent scientists- Isamu Akasaki, Hiroshi

Amano and Shuji Nakamura “for the invention of efficient blue light-emitting diodes which has enabled

bright and energy-saving white light sources”. - The Royal Swedish Academy of Sciences.

• Isamu Akasaki and Hiroshi Amano worked together at the Nagoya University primarily in developing high

quality GaN crystals and Shuji Nakamura was working on GaN based devices at the Nichia Corp during

the 90s.

• This report delves into understanding how information diffused among these inventors by mining and

exploiting information from the patent database.

• The patents pertaining to the key milestones in the LED history are analyzed to determine knowledge

transfer patterns.

• LEDs are highly energy efficient and are long lasting. They are constantly improved, getting more

efficient with higher luminous flux per unit electrical input power. The most recent record is just over

300 lm/W by CREE.

November 2014 Copyright © 2014, Relecura Inc. 2



http://www.nobelprize.org/nobel_prizes/physics/laureates/2014/press.html

http://www.cree.com/News-and-Events/Cree-News/Press-Releases/2014/March/300LPW-LED-barrier

Methodology

• Around 45 milestones in the field of LED technology are depicted using an interactive timeline.

• The report delves into the foundations of LED technology laid by eminent inventors of the first Infra-Red

(IR), Red, Yellow and Violet LEDs and analyzes if these technologies have had a direct impact on the Blue

LED invention or not.

• Analysis and conclusions are obtained by mining information from the patent database and mapping

knowledge spillovers using the patent citations network of the seminal patents.

• The technology focus and strengths of the seminal patents in Blue LED technology are understood by

using the ‘Relecura Technology Categories’ and the ‘Relecura Patent Quality’ metric.

• An analysis of the patent - US5578839 by Shuji Nakamura et al. and its citations was carried out to

understand the salient features of the invention and the various problems existing then, in the field of

GaN based hetero-structure devices.




https://search.relecura.com/details.php?docId=547d445358c870.31878795

Key Findings

• No direct relationship between the seminal BLUE LED patents and each of IR LED patent, Red LED patent

and the yellow LED patent.

• Dense cloud of patents around the Shuji Nakamura’s patent followed by Isamu Akasaki and Maruska’s

patents indicating vast scope of use and great potential.

• A number of patents have directly built on the seminal Blue LED patents with a considerable number of

high strength patents that have stemmed from a combination of two or three of the seminal Blue LED

patents.

• Key application areas of the Blue LED invention include – Semiconductors, Optics, Lighting,

Photolithography, Medical Technologies among other areas.

• The use of the Blue LED technology in Drugs and Medical Chemistry gained prominence since 2003.




Table of Contents


1. LED Technology

• Quick Facts

• Energy Efficiency

• Dramatic cost reductions trends

• Reduction of CO2 Emissions

• Key considerations of LEDs and LED driver circuits

• LED packaging and die design trends

2. LED Technology - Timeline

3. Patent Citation Analysis of Milestones

• Patent citation layout of seminal patents

• Patent graph layout with ‘Relecura Patent Quality’

4. Blue LED Technology

• Why is the Blue LED technology so important ?

• Key excerpts from the seminal patent –US5578839

• Citations analysis and summary of problems –US5578839

• Salient features of the invention – US5578839

• Properties of GaN based compounds

• Properties of Double Hetero-structure devices

• Geo-Spatial patent citation network analysis of US5578839



LED Technology

November 2014 © Relecura Inc. 6



LED Technology – Quick Facts

• Light Emitting Diodes (LED) are p-n junction diodes and emit light ofa particular wavelength when activated.

• LEDs are highly energy efficient and are long lasting. They areconstantly improved, getting more efficient with higher luminousflux per unit electrical input power. The most recent record is justover 300 lm/W by CREE.

• LEDs are ubiquitous and are applied inhousehold/industrial/automobile lighting, backlighting, medicalequipment and in a host of other applications.

• The LED lighting system market is expected to grow rapidly from2015. In terms of revenue, the market is expected to reach $55billion by 2020, from a mere $93 million (2012), with a high growthrate of 92.4% CAGR (ResearchANDMarkets report, 2012).


Royal Swedish Academy of Sciences



http://www.cree.com/News-and-Events/Cree-News/Press-Releases/2014/March/300LPW-LED-barrier

LED Technology – Macro level drivers

Macro level drivers in LED Lighting-

• Energy Efficiency

• Dramatic Cost reductions trend

• Reduction of CO2 emissions (Sustainable practices & Carbon crediting)





1) Energy Efficiency:The many levels at which Energy Efficiency in LED setups is being improved are-

• At an epitaxy level, one of the pivotal drivers is the furtherance of the critical production step- MOCVD (metalorganic chemical vapor deposition). Efficient production handling, better choice of layer material and substratematerial are the other driving points.

• At a chip level, multiple activities, such as the recent introduction of laser liftoff/flip-chip technology andsurface roughening, both of which minimizing light loss at the chip level.

• At a package level, initiatives are being taken to increase the amount of output light and to maintainhermetical sealing. Various options include - changing the optical material, adding a remote phosphor lightsource, using ultra-high reflectivity elements.

• At a module level, LED driver design will continuously be refined to improve wall plug efficiency, whileenhancing secondary optics can reduce light loss.

• Supporting tech (Monitoring and Lighting Control Systems)- advancements in low-power wirelesscommunications, and introduction of low-cost, multi-function smart sensors continue to minimize Total Cost ofOwnership of LED systems.





2) Dramatic Cost Reductions Trend• Material costs are falling. Sapphire substrate is one of the most expensive components of LED material costs today is

the sapphire substrate. Using silicon instead of sapphire can significantly reduce substrate costs.(SiC, GaN, zinc oxide (ZnO) and silicon (Si) substrates are considered as the future LED substrates, thanks to low lattice mismatches.)

• Downsizing the LED package.

• Shift from 2- to 4-inch wafers to 6- or 12-inch wafers can greatly improve the throughput of the MOCVD process.

• Chip on Board technologies are being explored that integrate the package and module step.

3) Reduction of CO2 emissions• “The investment for substituting incandescent or CFL lighting with LED is a fifth of the investment for installing solar

power, calculated on a ton CO2 emission p.a. basis. Which means subsidizing LED is a more efficient investment than subsidizing solar power from a government perspective.” – Lighting the way: Perspectives on the global lighting market, McKinsey




LED Technology – Design level drivers

Key considerations of LEDs/ LED driver circuit:

• Constant Current (CC) Drive requirement across a potentially wide voltage range

• Efficient SMPS (Switch Mode Power Supply) Design

• Dimmer Compatibility

• Reduction of Light Flicker

• Heat Sink design / Thermal path of LEDs (Thermal management)

• Optical Design

LED packaging and die design trends

• Chip-on-Board (COB) LEDs

• Phosphor coatings methods

• Deposited silicone primary lens systems

• New kinds of chips – (Soraa GaN on GaN , Verticle Hexagonal Chip – Verticle LED design)

• Usage of high purity gases (NH3,N2,H2) in the MOCVD process

• High Voltage and AC LEDs


Weir, B.- High Brightness LED Driver Solutions for General Lighting World of Lighting, ON Semiconductor



LED Technology - Timeline




LED Technology Timeline


Click for an interactive timeline



http://bit.ly/timelineLED




LED Technology Timeline

• From the timeline six milestones up to the invention of the Blue LED was considered for analyzing the technology trail and identifying knowledge spillovers.

• The key events considered are:

• For the above patents the citations was extracted from Relecura and the citation network is rendered for further analysis.


Milestone Publication

Number

Source Filing Year

Invention of the first IR- LED by Biard and

Pittman

US3293513 http://en.wikipedia.org/wiki/James_R._Biard 1962

Invention of the Red LED by Nick Holonyak US3249473 http://en.wikipedia.org/wiki/Nick_Holonyak 1965

Invention of the Yellow LED by Craford Magnus

George

US3873382 http://en.wikipedia.org/wiki/M._George_Craford 1972

Work on Violet LED by Maruska et al. at RCA

labs

US3819974 http://www.oregonlive.com/silicon-

orest/index.ssf/2014/10/oregon_tech_ceo_says_nobel_pri.

html

1973

Work on Blue LED by Isamu Akasaki, Hiroshi

Amano et al. at Nagoya University, Japan

US5122845 http://www.sandia.gov/~jytsao/WCS.pdf 1990

Work on Blue LED by Shuji Nakamura at Nichia

Corp, Japan

US5578839 http://www.sandia.gov/~jytsao/WCS.pdf 1993



https://search.relecura.com/details.php?docId=547d47db7854c3.84243246

http://en.wikipedia.org/wiki/James_R._Biard

https://search.relecura.com/details.php?docId=547d484d051379.19055757

http://en.wikipedia.org/wiki/Nick_Holonyak

https://search.relecura.com/details.php?docId=547d48204a25e7.35142644

http://en.wikipedia.org/wiki/M._George_Craford

https://search.relecura.com/details.php?docId=547d47253ead88.99172057

http://www.oregonlive.com/silicon-orest/index.ssf/2014/10/oregon_tech_ceo_says_nobel_pri.html

https://search.relecura.com/details.php?docId=547d4809712994.87473805

http://www.sandia.gov/~jytsao/WCS.pdf


http://www.sandia.gov/~jytsao/WCS.pdf

Patent Citation Analysis of Milestones






Key features of the graph-• The nodes in the graph indicate patents.

• The edges indicate citation links between the patents.

• The size of a node indicates a specific parameter.

• The direction of knowledge flow can be understood byfollowing the edges in a clockwise direction.

• One level of forward and backward citations areconsidered in the analysis.





Yellow LED patent

[1972]

IR LED patent

[1962]

Violet LED patent by

Maruska

[1973]

Blue LED patent by

Akasaki et al.

[1990]

Blue LED patent by

Shuji Nakamura

[1993]


Number

No. of Fwd.

Citations

Invention of the first IR- LED by

Biard and Pitman

US3293513 117

Invention of the Red LED by Nick

Holonyak

US3249473 17

Invention of the Yellow LED by

Craford Magnus George

US3873382 7

Work on Violet LED by Maruska et

al. at RCA labs

US3819974 199

Work on Blue LED by Isamu

Akasaki, Hiroshi Amano et al. at

Nagoya University, Japan

US5122845 225

Work on Blue LED by Shuji

Nakamura at Nichia Corp, Japan

US5578839 408

Red LED patent

[1965]

Node size scaling

0 408No. of Fwd. Citations

The patent with the most number of forward citations is the one of Shuji Nakamura’s with 408 forward citations followed by Akasaki and Hiroshi’s patent with 225 forward citations.










© Relecura Inc. 18

IR LED patent

[1962]


Maruska

[1973]

Blue LED patent by

Akasaki et al.

[1990]

Blue LED patent by

Shuji Nakamura

[1993]

• Number of patents which have a direct link to the seminal patents

• The numbers in the table illustrate the impact each seminal patenthas in the LED space.

• The IR LED, Red LED, Yellow LED inventions have a relatively lesserimpact in this tech area when compared to the Blue LED work.This analysis also gives us an idea as to why the Blue LED inventorswere chosen for the Nobel Prize rather than the trailblazers in theLED field.

Seminal patent of No. of Patents

Nakamura 266

Akasaki 196

Maruska 51

Nakamura & Akasaki 4

Akasaki & Maruska 10

Nakamura & Maruska 123

Nakamura, Akasaki & Maruska 15

Red LED patent

[1965]

November 2014

Yellow LED patent

[1972]




• The size of the node in this graph indicates its ‘Relecura PatentQuality’ score.

• The count of forward citations is a recognized metric for patentquality but is a vague indicator of patent strength. ‘Relecura PatentQuality’ is a proprietary metric related to patent valuation, qualityand monetization potential of each individual patent.


IR LED patent

[1962]

Red LED patent

[1965]


Maruska

[1973]

Blue LED patent by

Akasaki et al.

[1990]

Blue LED patent by

Shuji Nakamura

[1993]

Node size scaling

0.5 4.5Relecura Patent Quality

Yellow LED patent

[1972]





IR LED patent

[1962]

Red LED patent

[1965]


Maruska

[1973]

Blue LED patent by

Akasaki et al.

[1990]

Blue LED patent by

Shuji Nakamura

[1993]


Number

Relecura

Patent

Quality

Average

Relecura

Patent

Quality of

Fwd. citations

Median

Relecura

Patent

Quality of

Fwd. citations

Average

Relecura

Patent Quality

of Bwd.

citations

Invention of the first IR-

LED by Biard and

Pitman

US3293513 1.5 2.568 3 1.166

Invention of the Red

LED by Nick Holonyak

US3249473 1 1.294 1 1

Invention of the Yellow

LED by Craford Magnus

George

US3873382 1 1.285 1.5 1

Work on Violet LED by

Maruska et al. at RCA

labs

US3819974 1 2.761 3 NA (No

backward

citations)

Work on Blue LED by

Isamu Akasaki, Hiroshi

Amano et al. at Nagoya

University, Japan

US5122845 2.5 2.431 2.5 1.533

Work on Blue LED by

Shuji Nakamura at

Nichia Corp, Japan

US5578839 4 2.717 2.5 1.2272

Highest RelecuraPatent Quality among the seminal patents

Highest RelecuraPatent Quality for the

forward citations

Yellow LED patent

[1972]











IR LED patent

[1962]

Red LED patent

[1965]


Maruska

[1973]

Blue LED patent by

Akasaki et al.

[1990]

Blue LED patent by

Shuji Nakamura

[1993]

IR LED patent

[1962]

Red LED patent

[1965]

Violet LED patent

[1973]

Blue LED patent by

Akasaki et al.

[1990]

Blue LED patent by

Shuji Nakamura

[1993]

<-Forward Citations

Relecura Patent Quality ->

Yellow LED patent

[1972]

Yellow LED patent

[1972]

Click for an interactive graph Click for an interactive graph



https://relecura.com/misc/network-2/


http://goo.gl/opLZLg

http://goo.gl/opLZLg





• Key Findings:

• No direct relationship between the BLUE LED patents and each of IR LED patent, Red LED patent and the yellow LEDpatent.

• Dense cloud of patents around the Shuji Nakamura’s patent followed by Isamu Akasaki and Maruska’s patents.

• Considerable number of patents have directly built on the seminal Blue LED patents and a number of patents have alsostemmed from a combination of two or three of the seminal Blue LED patents.

• Shuji Nakamura’s Blue LED patent has got the highest Relecura Patent Quality among the seminal patents followed byAkasaki and Amano’s patent.

• Considerable number of quality inventions were also built upon Maruska’s violet LED patent.



Patent Citation Analysis of Milestones –Blue LED patents

• A snapshot of three seminal patents related to the BLUE LED tech isshown.

• The graph is filtered to patents with degree 2 and above to reducedensity and to understand knowledge transfer patterns.


Blue LED patent by

Akasaki et al.

[1990]

Blue LED patent by

Shuji Nakamura

[1993]


Maruska

[1973]

US5237182

Click for an interactive graph

[email protected]

Blue UV LED patent assigned to Sharp





https://search.relecura.com/details.php?docId=547d466e959ef4.92077266


Seminal Patents and their Citations

• Details of the patents and its citations considered in the study areavailable here.

• The seminal patents considered are

• Click to view the seminal patents and their citations.



Number

Filing Year

Invention of the first IR- LED by Biard and

Pittman

US3293513 1962

Invention of the Red LED by Nick Holonyak US3249473 1965

Invention of the Yellow LED by Craford Magnus

George

US3873382 1972

Work on Violet LED by Maruska et al. at RCA

labs

US3819974 1973

Work on Blue LED by Isamu Akasaki, Hiroshi

Amano et al. at Nagoya University, Japan

US5122845 1990

Work on Blue LED by Shuji Nakamura at Nichia

Corp, Japan

US5578839 1993



http://goo.gl/RYKpgt

http://goo.gl/RYKpgt







BLUE LED Technology




BLUE LED Technology- Why so important ?

• The Blue LED invention is a breakthrough that came after 20 years of intense research and developmentsince the previous milestone – The Purple LED. The Blue LED invention is not just important because ofthe tremendous and prolonged amount of work and dedication that was put into it but also because itopened avenues to a whole new world of lighting and igniting hopes of bringing light to the 1.5 billionpeople who don't have it.


The Blue LED invention was the final piece of the puzzle tocreate white light from an R-Y-B combination. Now, whitelight is created by using either this RYB combination or byemploying a phosphor coating over a Blue LED.

This led to LEDs being used ubiquitously inhousehold/industrial/automobile lighting, backlighting,medical equipment and in a host of other applications. http://energy.gov/eere/ssl/led-basics



Blue LED technology- US 5578839

US 5578839 - Light-emitting gallium nitride-based compound semiconductor device by Shuji Nakamura

• The present invention relates to a light-emitting gallium nitride-based compound semiconductor device and, moreparticularly, to a light-emitting compound semiconductor device having a double-hetero structure capable of emitting high-power visible light ranging from near-ultraviolet to red, as desired, by changing the composition of a compoundsemiconductor constituting an active layer (light-emitting layer).

Key excerpts from the background section of the seminal patent-

• “All conventional LEDs are unsatisfactory in both output power and luminance, and have no satisfactory luminosity.”

• “No LED of double hetero-structure are known, in which the double hetero-structure is entirely formed of low resistivity GaNbased compounds and at same time has a light emitting layer of low resistivity, impurity doped InGaN.”







On analyzing multiple level backward citations of this patent we observe that-

• Double hetero-structure light emitting semiconductors were developed since 1988.

• Shift from GaAs, GaP based semiconductors to GaN based compound semiconductors from 1980s.

• Patents related to Photodiodes and solar cells (employ counter mechanism to that of LEDs) act as feeders to the system dating back to 1973.

• Insights on various experimentations on the type of substrate and buffer layer used in order to reduce lattice mismatches for GaN based compound semiconductors from 1980s.

Summary of key technical problems from the background of the patent

• Inability to achieve LEDs of sufficient brightness in the BLUE wavelength band that are of practical use.

• Lattice mismatches in hetero-junction structures due to differences in atomic arrangement of the semiconductor and buffer layers employed.

• Conventional epitaxial methods involve low controllability in doping impurity due to the need for high temperature of operation.

• Difficulty in the manufacture of bulk GaN.






Salient Technical Features of the Invention-

• Different compositions for each GaN based semiconductor layer indicated in the figure by different dotted lines.

• All the GaN compound based layers possess Low Resistivity (LR).

• The light emitting Indium Gallium Nitride (InGaN) layer is impurity doped.

Field of the Invention-

• Visible light emitting semiconductor device which is excellent in output power, luminance and luminosity for the first time.

• Ranging from Near UV to RED (365-620nm) (by changing composition of light emitting layer).


http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Fundamentals/Electromagnetic_Radiation





Properties of GaN based compounds-

• GaN, GaAlN, InGaN have a direct band gap andBG= 1.95 eV to 6 eV. Thus requiring relativelylesser energy to excite and improving electrical tolight conversion efficiency.

• GaN based compounds are relatively better instability when compared to GaAs, GaP etc.

Properties of Double Hetero-Structure devices-

• Relatively better luminance compared to existingMIS (Metal-Insulator-Semiconductor) type homo-junction semiconductors.

• Relatively higher light emitting output powercompared to existing MIS type semiconductors.


1. Wikipedia. 2013. Direct and indirect band gaps. [online] Available at: http://en.wikipedia.org/wiki/Direct_and_indirect_band_gaps

[Accessed: 6 Dec 2013].





Experimental results described in patentdocument-

• Obtaining a higher intensity at ~480nm(BLUE) when the light emitting layer is doped.

• Experiments also indicate the effect ofvarying the thickness of the light emittinglayer on the relative light intensity obtained.


Nakamura, Shuji. Multilayer Elements with Indium Gallium Nitride on Clad Layers, Dopes for P-n Junctions. Nichia Chemical Industries, Ltd.,

assignee. Patent US5578839. 26 Nov. 1996.





Geo Spatial Layout -

• In this Geo-Spatial Layout, the Longitudescorrespond to the year of filing of thepatent, and the latitudes correspond todifferent technology buckets.

• The nodes indicate patents and the sizeof the nodes is proportional to thenumber of forward citations.

• This layout consists of two level forwardand backward citations of the seminalpatent – US5578839.






https://search.relecura.com/details.php?pnum=US5578839A









Observations:

• The tech areas contributing to Blue LED invention are (From the backward citations)a) Semiconductorsb) Photolithographyc) Opticsd) Domestic Appliances

• The prominent technologies that spun out of this invention/technology are (From forwards)a) Semiconductorsb) Drugs & Medical Chemistryc) Photolithographyd) Opticse) Lighting

• It can observed that the use of the Blue LEDtechnology in Drugs and Medical Chemistry gainedprominence since 2003-2005.


















• Various Relecura Technology Categories representdifferent latitudes with weighted edges connecting‘similar’ patents.

• The size of the node is proportional to the‘Relecura Patent Quality’ of that patent.

• It is worth noting that a significant number of linksalso emerged from areas viz. Sealing materials anddrilling fluids; Nanostructure applications;Dentistry – Oral care and Crystal Growth.

• The vast breadth of applications of the Blue LEDtechnology is clearly evident from the layout.


Unclassified












Disclaimer

This document is provided for information purposes only and the contents hereof are subject to change without notice. This document,including the information and analysis and any opinion or recommendation, is neither legal advice nor intended for investment purposes. Thisdocument is not warranted to be error-free, nor subject to any other warranties or conditions, whether expressed orally or implied in law,including implied warranties and conditions of merchantability or fitness for a particular purpose. Relecura Inc. specifically disclaims anyliability with respect to this document and no contractual obligations are formed either directly or indirectly by this document.

Relecura is a web-based patent and portfolio analysis platform that uses a knowledge discovery framework to simplify IP analysis for prior-artsearch, technology landscaping, competitive intelligence, and IP commercialization activities. For more details visit www.relecura.com or writeto [email protected].


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