transparent conducting oxides - cdtpv

2TCO Workshop, University of Liverpool

Transparent Conducting Oxides –An Industrial Perspective

• How are TCO’s made on an Industrial Scale?

• How are TCO’s used in Industry?

Jack Brown- Technologist - NSG Group

3

Jack Brown – Jack.Brown@nsg.comTechnologist, On-line CoatingsNSG European Technical Centre

Lathom, Lancs. UK.

European Technical Centre, Lathom

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NSG Group R&D Facility

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Global Flat Glass Market

• Glass is generally traded in three main markets, buildings, automotive and special applications.

• Most of the world’s float glass goes into buildings (80%). Automotive applications account for around (10%) . The rest is used for other applications

NSG – (Nippon Sheet Glass)

• Who are we?

• Where do we operate from?

• Where are we heading?

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NSG Group

• Principal operations in 28 countries

• Ownership/interests in 46 float lines

• Employs around 27,000 people

• Sales in 130+ countries

• €54million investment in R&D in FY2013

• €74million investment in R&D in FY2016

• 2011 - The NSG Group is one of four glass groups producing around 50 percent of the world’s high quality glass.

• 2017 – Over 50% of glass is produced in China

Global Operations

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Expansion of Value-Added Business

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High value-added products will drive future growth

The Float Glass Process

• Pilkington float process is at the heart of the worldwide industry.

• Operates non-stop for 10-15 years

• 6000 km/year

• 0.3 mm-25 mm thick, up to 3 m wide

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Melting

furnace

Float

bath

Cooling

lehr

Continuos

ribbon of

glass

Cross

cutters

Large plate lift-

off devices

Small plate lift-

off devices

Raw material feed

TCO’s – Transparent Conducting Oxides•What are they?

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Transparent Conducting Oxides

• TCOs are used wherever electrical conductivity and transparency are required

• Different applications use different aspects of the TCO properties

• Thin film solar cells make use of the electrical conductivity to collect electrons generated by the photoactive materials

• Glazing applications make use of the high reflectance at long wavelengths

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• Low-Emissivity and Solar Control Coatings

• In a double glazed unit, a low-emissivity coating on the inner pane reduces radiation into the cavity

Low-Emissivity and Solar Control Coatings

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• A wide variety of coating technologies are utilised by the glass industry

– Spray Pyrolysis

– Powder Spray

– Chemical Vapour Deposition

– Sputter Coating

– Thermal Evaporation Coatings

– Sol Gel Coatings

• These are applied

– On-Line i.e. as the glass is produced on the float line

– Off-Line i.e. coating not necessarily produced at the same location

Manufacturing a Functional Coating

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Variations of CVD

• Atmospheric Pressure – APCVD• Low Pressure - LPCVD• Metal-organic – MOCVD • Aerosol Assisted – AACVD

• Combustion/Flame – CCVD• Hot Wire/Filament – HWCVD/HFCVD• Plasma Enhanced - PECVD• Laser Assisted – LACVD• Microwave Assisted – MWCVD• Atomic Layer Deposition – ALD

Broadly termed thermal CVD methods

Broadly termed activated CVD methods

3 Main TCOs

• FTO – Fluorine doped Tin Oxide

• Manufactured by Atmospheric Pressure Chemical Vapour Deposition (APCVD)

• ITO – Indium doped Tin Oxide

• Manufactured by Sputtering, Physical Vapour Deposition (PVD)

• AZO – Aluminium doped Zinc Oxide

• Manufactured by Low Pressure Chemical Vapour Deposition (LPCVD), Plasma Enhanced Chemical Vapour Deposition (PECVD) or Atomic Layer Deposition (ALD)

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Basics of APCVD

Several stage process culminating in a gas phase

reaction to produce a thin film on the glass surface.

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Basics of APCVD

• Vaporisation of a volatile precursor

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Basics of APCVD

• Transport of the chemicals with inert and reactive

gases to a suitable reaction chamber.

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Basics of APCVD

• chemical reaction and

formation of coating in controlled

temperature regime.

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Basics of APCVD

• Removal and neutralisation

of by-products

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CVD on Glass

For on-line coating of glass we require:

• High growth rates – required thickness (00s nm) in <2 s

• Stable chemistry – uniform coatings for continuous operation for many days

• Good adhesion to glass

• High efficiency – reduce costs – can be hard as organometallic precursors used tend to be costly

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APCVD Strengths and Weaknesses

Strengths Weaknesses Result

On-line coating possible

Reduced flexibility Reduced labour costs, high volume manufacture

Fresh substrate surfaces

No washing step, enhanced adhesion

High deposition rates Need to match line speed

Thick films possible with high throughput

Hard films Improved processability and performance

Structure control possible e.g. crystallinity

Rough surface Improved functional properties and durability

Volatile precursors required

Limited range of materials

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Float Glass Plant

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Float Glass Plant

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Float Glass Plant

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Float Glass Plant

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On-Line Coating Position

Load raw

materials

Float line Process

TCO Coated glass supply chain

On-line APCVD

T 650°C

1500 oC

Melting 600 oC

1050 oC

Floating

Cooling

Turbulent Flow CVD Coater

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Topcoat Beam RHS Section View

TunnelSkirtAir curtain

SkirtAdjust

Air curtaininlet pipe

Water cooling

In out

Slot1 Slot2

Glass flow

Exhaust manifoldassembly

Extraction slot

Downstreamwater box

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• SnCl4 + H2O + HF SnO2:F + HCl (~1.5 at% F)

• Much gas phase reaction

• Gases introduced separately in turbulent flow regime

• Very high growth rates >100 nm/s possible

• Low precursor efficiency <10%

SiCxOy (70 nm)

SnO2:F (350 nm)

Glass

• SiH4 + C2H4 + CO2 SiCxOy + H2O + other by-products

• Used as colour suppression and barrier layer

CVD of SnO2:F –Pilkington K Glass™ a Low-E Coating

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Low Emissivity Coating – PilkingtonK Glass™

• SiCO under layer used as a blocking layer and colour suppressant

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Laminar Flow CVD Coater – 2nd

Gen coaters

Glass

Glass Ribbon Flow

Up-Stream Exhaust

Down-Stream Exhaust

Precursor gases in manifold

Outside Atmosphere

CVD of SnO2:F – Common Precursors – How could we make it more efficient?

• Tin Oxide Precursors

• Dimethyl Tin Dichloride (DMT)

• Monobutyl Tin Trichloride (MBTC)

• Stannic Chloride (SnCl4)

• Fluorine Dopant Precursors

• Hydrogen Fluoride (HF)

• Trifluoro Acetic Acid (TFA / TFAA)

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Challenges Facing On-Line Coatings

• Delivering precursors at a constant temperature and flow.

• Maintaining a constant uniformity across a 3 metre ribbon at a speed of up to 15 m/min for as long as possible.

• Longest coatings run time is currently ~60 hours.

• Quality Control – Continuously Inspecting and Monitoring the product being produced.

• Warehouse and other ‘cold-end’ activities.

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3 Main TCO’s

• FTO – Fluorine doped Tin Oxide

• Manufactured by Atmospheric Pressure Chemical Vapour Deposition (APCVD)

• ITO – Indium doped Tin Oxide

• Manufactured by Sputtering, Physical Vapour Deposition (PVD)

• AZO – Aluminium doped Zinc Oxide

• Manufactured by Sputtering, Low Pressure Chemical Vapour Deposition (LPCVD), Plasma Enhanced Chemical Vapour Deposition (PECVD) or Atomic Layer Deposition (ALD)

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The Sputtering Process

+-

ArAr+e-

PumpsProcess Gas

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In-Line Production Coater

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Typical Plant Layout – for Continuous Coating

Coating ZoneTransfer

Chamber

Transfer

Chamber

Load

Lock

Washing

Machine

Inspection

Room

Exit

Lock

Glass Transport Direction

Vacuum Plant

Sp

ee

d

Position

Leading Edge Speed

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Sputtering Plant – OLC1

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Sputtering Plant – OLC1

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Sputtering Plant – OLC1 – Not Pilkington Technology

• £16 million cost for the coater

• £40 million cost for the entire site installation.

• Able to coat ‘Jumbo’ sized plates (6m x 3.21m).

• Able to coat ~10 million m2 a year.

• Ability to produce single and double silver coatings (not triple, yet…)

• Single silver coatings for Low-E products.

• Double silver coatings for Solar Control products.

• Able to make TCO’s but not as viable as FTO already produced at UK5

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Comparison – SnO2:F vs ZnO:Al

• ZnO:Al offers better optical and electronic properties over SnO2:F

• After etching AZO significantly enhances light scattering. This is a benefit for materials that don’t absorb well at long wavelengths

• SnO2:F is more stable than AZO in chemical durability tests.

• SnO2:F is cheaper than ZnO:Al

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NSG Products

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Coated Products

• Coated Products Divided into 3 groups;

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Building Products

• Low Emissivity

• Solar Control

• Functional Products

NSG TEC™Products

• Electronic display apps.

• White goods market (freezer lids, etc.)

• OFC Substrates

Solar Products• Conductive substrates for solar cell

fabrication.

Pilkington Energy Advantage™

• Pilkington Energy Advantage™ is a low emissivity coating sold predominantly into colder areas of the United States and is basically Pilkington K Glass™ made using oil cooled beams.

• Different precursor chemistry, same end result. Main difference for the end user is slightly more hazy than Pilkington K Glass™– though we can’t sell Pilkington Energy Advantage™ as Pilkington K Glass™.

• Like discussed before, do not use Stannic Chloride, instead use DMT.

• Low emissivity feature reduces heat loss from a building by reflecting heat back into the building.

• Emissivity is the measure of how efficient the coating is at reflecting heat.

• Clear glass allows ~89% of heat to escape, Pilkington Energy Advantage™ only ~15%.

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Pilkington Energy Advantage™

• Pilkington Energy Advantage™ / NSG TEC™ 15 coating is made up of three layers.

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Pilkington Energy Advantage™

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Pilkington Energy Advantage™

coating

Pilkington Eclipse Advantage™

• Product is a Solar Control coating designed to reduce solar heat from entering a building.

• Designed for commercial building applications and produced on a range of tints to provide aesthetic performance.

• Tint colour is seen from outside of building and not obscured by coating.

• Solar control performance changes with tint.

• Predominantly used on surface #2 of an IGU though can be used as a single pane.

• Glass side reflection dictates how the product looks from the outside.

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Pilkington Eclipse Advantage™

• Pilkington Eclipse Advantage™ is made up of four layers.

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Pilkington Eclipse Advantage™

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Pilkington Eclipse Advantage™

Coating on #2 Surface

NSG TEC™ Products

• NSG TEC™ products developed as a spin off from Pilkington Energy Advantage™ for electronic applications.

• Currently used as;

• Transparent, electrically conductive articles - i.e. heated freezer cabinets.

• TCO Substrates for additional devices – i.e. LCD displays.

• TCO products are basically a variation of top F:SnO2 layer to give different sheet resistance values or morphology.

• Originally made to order products for specific customers but formed the basis of the Solar Energy portfolio.

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NSG TEC™ Glass Applications

• Thin Film Photovoltaics

• Electrochromic Mirrors

• Commercial Refrigeration

• Oven Windows/White Goods

• Heated Glass

• Displays

• Sodium blocking for sputter coating processors

• Thermochromics

• Lighting

• Numerous other specialty applications

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NSG TEC™ Glass Properties

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NSG TEC™ Product

Available Thickness

(mm)

Sheet Resistance

(Ohms/square)

Visible Transmittance

(%)

Haze

(%)

Hemispherical Emittance

NSG TEC™ 7 2.2, 3.0, 3.2 6 - 8 80 – 82 5 0.12

NSG TEC™ 8 2.2, 3.2 6 - 9 80 – 81.5 12 0.12

NSG TEC™ 15

2.2, 3.0, 3.2 12-14 82 – 83 ≤0.35 0.15

4.0, 5.0, 6.0, 8, 10 12-14 83 – 84.5 ≤0.75 0.15

NSG TEC™ 20 4.0 19 - 25 80 – 85 ≤0.8 0.21

NSG TEC™ 35 3.2, 6.0 32 - 48 82 – 84 ≤0.65 0.34

NSG TEC™ 50 6.0 43 - 53 80 – 85 ≤0.55 0.38

NSG TEC™ 70 3.2, 4.0 58 - 72 82 – 84 0.5 0.45

NSG TEC™ 250 3.2, 4.0 260 - 325 84– 85 0.7 0.67

NSG TEC™ 1000 3.2 1000 - 3000 88 0.5 0.78

NSG TEC™ Products for Solar Applications

• Solar products are based around the Pilkington Energy Advantage™ system with variation in either layer thickness or chemistry.

• Products tend to be manufactured for a single customer rather than same product for multiple customers.

• Products generally form the base plate for solar cells with customers then adding further coatings on top of our materials.

• Solar customers are very strict in terms of specifications and defects – need to qualify the product with each customer.

• Also need products to be exactly the same across each of the manufacturing sites to improve logistics.

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NSG TEC™ Glass Properties

• NSG TEC™ products used in the majority of thin film PV technologies.

• TCO properties, optimised for each PV technology.

• Light transmission.

• Coating conductivity.

• Haze.

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Thin film siliconNSG TEC™A8 High haze, rough coating

TCO coating

Surface roughness

CdTeNSG TEC™C15Low haze, smooth coating

TCO coating

Surface roughness

NSG TEC™ Glass Appliance Applications

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Commercial Refrigeration and Freezer Applications

Passive Active Curved

NSG TEC™ Glass Appliance Applications

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Commercial Food Warmers

Oven Door Glass

Touch Panel Applications – NSG TEC SB (capacitive), NSG TEC 1100 (Resistive)

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Video Gaming Systems

Airport Check-In Terminals GPS Systems

NSG TEC™ Glass in Heated Windows

• The use of NSG TEC™ Glass for other heated applications is increasing

• Restaurants and residences in cold climates are increasing the comfort level surrounding picture windows.

• Eliminates the cold-shoulder effect with radiant heat.

• Reduces heat loss through the windows and the need to over-heat the entire room to compensate.

• Maintains window clarity and preserves spectacular views.

• Eliminates condensation.

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Heated Window Applications

• Residential Application – Exterior

• Photo and Application – Courtesy of Radiant Glass Industries LLC

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Heated Window Applications

• Residential Application – Interior

• Photo and Application – Courtesy of Radiant Glass Industries LLC

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Heated Window Applications

• Restaurant Application - Mahogany Grille, Durango Colorado

• Photos and Application – Courtesy of thermique™

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Industrial Transportation

• Can incorporate active or passive defrosting capability in many applications;

• Military vehicles

• Tank Turrets

• Humvees

• Marine Glazing

• Military

• Private Yacht

• Locomotive glass

• Siemens & General Electric (GE)

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Industrial Transportation

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NSG TEC™ Glass in Electrochromics

• Increasing activity in large area commercial electrochromicdevelopment

• Much more difficult application than EC mirrors

• Smart window systems are in development for increased energy management

• Layered film solutions are also in development

• Large scale producers:

• Sage

• View Inc.

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Electrochromic Applications

• Photo and Application – Courtesy of Sage Electrochromics, Inc.

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• Club Porticello - Oconomowac, Wisconsin

• Overlooks scenic lake

• Windows face west into setting sun

• Need to preserve view while keeping diners comfortable

Electrochromic Applications

• Photo and Application – Courtesy of Sage Electrochromics, Inc.

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Summary

• Shown common manufacturing methods for 3 of the main TCO materials;

• Fluorine doped Tin Oxide (FTO) – manufactured by APCVD.

• Indium doped Tin Oxide (ITO) – manufactured by Sputtering.

• Aluminium doped Zinc Oxide (AZO) – manufactured by Sputtering, LPCVD, PECVD or ALD.

• Shown an incite into industrial applications of Transparent Conductive Oxides;

• Low-E, Solar Control and Technical Applications.

• Shown some of the products offered by NSG that use TCO’s.

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Thank you for you attention