Recent Trends in LED and LASER
Diode Device Material
Characterization
Yves Lacroix, PhD Physics
CEO at YSystems Ltd.

Overview of this Presentation
Focus of discussion
Technology advances and recent trends driving metrology technologies
Brief introduction to YSystems
Recent and ongoing development:
In Situ atomic roughness characterization of InGaN LEDs●
Detailed DBR property mapping of VSEL structures●
Optical characterization of phosphor wafers for white light LED/LD devices●
Simultaneous measurement of ultra-wide spectral ranges●
Mapping alloy concentration and strain in AlGaAs structures●Fully automated and customizable remote controllable wafer mapping●Overview of this Presentation
Focus of discussion
Technology advances and recent trends driving metrology technologies
Brief introduction to YSystems
Recent and ongoing development:
In Situ atomic roughness characterization of InGaN LEDs●
Detailed DBR property mapping of VSEL structures●
Optical characterization of phosphor wafers for white light LED/LD devices●
Simultaneous measurement of ultra-wide spectral ranges●
Mapping alloy concentration and strain in AlGaAs structures●Fully automated and customizable remote controllable wafer mapping●Overview of this Presentation
Focus of discussion
Technology advances and recent trends driving metrology technologies
Brief introduction to YSystems
Recent and ongoing development:
In Situ atomic roughness characterization of InGaN LEDs●
Detailed DBR property mapping of VSEL structures●
Optical characterization of phosphor wafers for white light LED/LD devices●
Simultaneous measurement of ultra-wide spectral ranges●
Mapping alloy concentration and strain in AlGaAs structures●
Fully automated and customizable remote controllable wafer mapping●Overview of this Presentation
Focus of discussion
Technology advances and recent trends driving metrology technologies
Brief introduction to YSystems
Recent and ongoing development:
In Situ atomic roughness characterization of InGaN LEDs●
Detailed DBR property mapping of VSEL structures●
Optical characterization of phosphor wafers for white light LED/LD devices●
Simultaneous measurement of ultra-wide spectral ranges●
Mapping alloy concentration and strain in AlGaAs structures●
Fully automated and customizable remote controllable wafer mapping●Optical Device Characterization Technology Advances
Focus on: Non-destructive, non-contact methods In Situ and Ex Situ
(Viewed from the perspective of an metrology solution provider)●●Destructive
Non-destructive○Contact○
Non-contact■
Passiveshape or image detection, electromagnetic reflection, refraction, transmission■
Activephotoluminescence, phosphorescence, thermoluminescenceSome modern technologies that make metrology easier and better
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The incredible increase in computing processing power
The availability of low cost compact lasers in a wide range of wavelengths
Speed and sensitivity of CCDs and detector arrays
Low cost robotics / automation hardware3D printing !
The internet of course!!

Some things that are still difficult●●●●

The physics of basic light sensor and light emitter materials
The understanding of the measurement itself and its implication
The design of a reproducible measurement system
Software programming!

What is driving characterization technologies●●●●

Need for ever higher efficiencies in display and lighting
New applications of NIR imaging such as facial recognition
Need for high emission DUV LEDs in the field of sterilization
Need for fully customized and automated characterization tools, including the possibility ofremote control (more so since the pandemic)

Introducing YSystems

Some of our customers and partners:

Location: Tokushima, Japan
Established: 2001 (20 years)

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YSystems Products and Services
Standard and Custom Products
YWaferTM - Wafer and thin film metrology mapping systems
YGrowthMonitorTM - Chamber customized in situ monitoring systems(featuring several patented technologies)
Services
Metrology instrument design, robotics, mechanical hardware andsoftware design, fabrication and assembly11

YWafertm Mapper Lineup

12Introducing YSystems

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Introducing YSystems

14Introducing YSystems

15

Introducing YSystems

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So what does such an instrument maker do with all these new available technologies andchallenges?

Create New instruments and Solutions.
In Situ atomic roughness characterization of InGaN LEDs
● Detailed DBR property mapping of VSEL structures● Optical characterization of phosphor wafers for white light LED/LD devices● Simultaneous measurement of ultra-wide spectral ranges● Mapping alloy concentration and strain in AlGaAs structures● Fully automated and customizable remote controllable wafer mapping●In Situ atomic roughness characterization of InGaN LEDs
● Detailed DBR property mapping of VSEL structures● Optical characterization of phosphor wafers for white light LED/LD devices● Simultaneous measurement of ultra-wide spectral ranges● Mapping alloy concentration and strain in AlGaAs structures● Fully automated and customizable remote controllable wafer mapping●Unique Patented In Situ Measurement Techniques with YGrowthMonitorTM

In Situ atomic roughness measurement in Green LED structures

Data Courtesy of：Amano Group, Nagoya U.

In Situ atomic roughness characterization of InGaN LEDs
Detailed DBR property mapping of VCSEL structures● Optical characterization of phosphor wafers for white light LED/LD devices● Simultaneous measurement of ultra-wide spectral ranges● Mapping alloy concentration and strain in AlGaAs structures● Fully automated and customizable remote controllable wafer mapping●●

VCSEL wafer Dip Wavelength Mapping(and many more useful DBR Parameters can be extracted using a single instrument)
DBR Center
DBR Width

VCSEL DipWavelength

Data Courtesy of：VIGO SYSTEM
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In Situ atomic roughness characterization of InGaN LEDs
● Detailed DBR property mapping of VSEL structures
Optical characterization of phosphor wafers for white light LED/LD devices● Simultaneous measurement of ultra-wide spectral ranges● Mapping alloy concentration and strain in AlGaAs structures● Fully automated and customizable remote controllable wafer mapping●●Phosphor material property mapping (a white LED in principle)

White light

Yellow phosphor

Blue light

A standard white LED is
composed a blue LED
partly exciting a yellow
phosphor and partlytransmitting.
The resulting white lighthowever depends on thebalance of these 2processes.

24Phosphor material property mapping (a white LED in reality)

White light

Yellow phosphor

In reality the transmitted
blue light and the emitted
yellow have a different
angular dispersion.
This will be affected by
the diffraction, absorption,and thickness of thephosphor material

Blue light25

Phosphor material property mapping (white LED simulated at each point)
2 optical paths to spectrometer
Optical thickness
measurement gauge

Optical Transmission
Wafer Mapping Stage

YWaferTM can be configured tomeasure and map a phosphor
plate by mimicking the white
LED configuration, to measure
the emitted spectrum at
multiple angles.
The thickness of the phosphor
plate can also be mapped indetail and superimposed withthe phosphor spectral
characteristics.

Blue light26

Phosphor material property mapping (actual distribution map)
Logarithmic scaled “white LED like”
spectrum from 2 different angles collected
at each point on the wafer

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Phosphor material property mapping (within wafer characteristics)

Measured Spectrum
Excitation blue LED spectrum

The mapped data displayed in a colour
distribution showing the trend within thewafer area

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In Situ atomic roughness characterization of InGaN LEDs
● Detailed DBR property mapping of VSEL structures● Optical characterization of phosphor wafers for white light LED/LD devices● Simultaneous measurement of ultra-wide spectral ranges● Mapping alloy concentration and strain in AlGaAs structures● Fully automated and customizable remote controllable wafer mapping●

Simultaneous measurements by multiple overlapped detector ranges(currently at the product implementation stage)
Splitting the optical signal to 2 separate
detector arrays (one a Si CCD, the otheran extended InGaAs sensor array) tocreate a single wide spectrum from lightmeasured simultaneously.

Si CCD
InGaAs detector array

In Situ atomic roughness characterization of InGaN LEDs
● Detailed DBR property mapping of VSEL structures● Optical characterization of phosphor wafers for white light LED/LD devices● Simultaneous measurement of ultra-wide spectral ranges● Mapping alloy concentration and strain in AlGaAs structures● Fully automated and customizable remote controllable wafer mapping●Real Time Mapping and Computation of Alloy Concentrations and Strain
Formula for calculating strain inInGaAs simply entered inYWaferTM to generate a strain
distribution map:
If([Wavelength]<1677,(((1.7142-((2162.3/[Wavelength]-0.2322)^0.5)/0.872+0.007*([Wavelength]-1677)/20)-0.532)*68500),(((1.7142-((2162.3/[Wavelength]-0.2322)^0.5)/0.872-0.0250*(1677-[Wavelength])/20))-0.532)*68500)

Data Courtesy of：VIGO SYSTEM
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In Situ atomic roughness characterization of InGaN LEDs
● Detailed DBR property mapping of VSEL structures● Optical characterization of phosphor wafers for white light LED/LD devices● Simultaneous measurement of ultra-wide spectral ranges● Mapping alloy concentration and strain in AlGaAs structures● Fully automated and customizable remote controllable wafer mapping●Fully automated custom measurement systems capable of remote operation

Come visit us at our booth for a fulldescription

Thank you for your attention

Special thanks to our customers and partners in Japan,
Europe and all over the world for the insightful
discussions and for providing us with some of the data
shown in this presentation
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YSystems
You can only improve
what you can measure36