transparent conducting oxides - from and industrial perspective

2 Wednesday 12th November

2014 TCO Workshop, University of Liverpool

Transparent Conducting Oxides – from an industrial perspective

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

•How are TCO’s used in Industry?

Liam Palmer, NSG Group

3

Liam Palmer – [email protected] Advanced Technologist, On-line Coatings

NSG European Technical Centre Lathom, Lancs. UK.

European Technical Centre, Lathom

Wednesday 12th November

2014 TCO Workshop, University of Liverpool

NSG Group R&D Facility


2014 TCO Workshop, University of Liverpool 4

Global Flat Glass Market

• Global market for flat glass in calendar year 2011 was approximately 59 million tonnes.

• At the level of primary manufacture, this represents a value of around €24 billion.

• Most of the world’s float glass goes into buildings. Automotive applications account for around 10 percent.



NSG Group

• Principal operations in 30 countries

• Ownership/interests in 48 float lines

• Employs around 28,000 people

• Sales in 130+ countries

• €54million investment in R&D in FY2013

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

World-leading supplier of ultra-thin glass for smart

phones and tablet devices. Our Ultra Fine Flat Glass (UFF) is produced in thicknesses as

low as 0.3-1.1mm. NSG annual report 2013

‘Making a Difference to

our World through

Glass Technology’

Global Operations



Expansion of Value-Added Business



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



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



Transparent Conducting Oxides

• TCOs are used wherever electrical conductivity and transparency are required

• Different applications use different aspects of the TCO properities

• 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



• Low-Emissivity and Solar Control Coatings

• In a double glazed unit, a low-emissivity coating on the inner pane blocks radiative heat trying to escape into the cavity

Low-Emissivity and Solar Control Coatings



• 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



Variations of CVD

• Atmospheric Pressure – APCVD • Low Pressure - LPCVD • Metalorganic – 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 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 Low Pressure Chemical Vapour Deposition (LPCVD), Plasma Enhanced Chemical Vapour Deposition (PECVD) or Atomic Layer Deposition (ALD)





Chemical Vapour Deposition

Animation kindly supplied by Dr. Warren Cross, University of Leicester



Chemical Vapour Deposition

Main gas flow region

Gas Phase Reactions

Surface Diffusion

Desorption of

Film Precursor

By Products

Diffusion

to surface



CVD on Glass

For on-line coating of glass we require:

• High growth rates – required thickness in <2 s

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

• Good adhesion to glass

• High efficiency – reduce costs



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



Float Glass Plant



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



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



• 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



Low Emissivity Coating – Pilkington K Glass™

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



Laminar Flow CVD Coater

Glass

Glass Ribbon Flow

Up-Stream Exhaust

Down-Stream Exhaust

Precursor gases

Outside Atmosphere

CVD of SnO2:F – Common Precursors

• 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)



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.



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)



The Sputtering Process

+ -

Ar Ar+ e-

Pumps Process Gas



In-Line Production Coater



Typical Plant Layout – for Continuous Coating

Coating Zone Transfer

Chamber

Transfer

Chamber

Load

Lock

Washing

Machine

Inspection

Room

Exit

Lock

Glass Transport Direction

Vacuum Plant

Sp

ee

d

Position

Leading Edge Speed



Sputtering Plant – OLC1




• £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.

• Single silver coatings for Low-E products.

• Double silver coatings for Solar Control products.

• No TCO’s are made at this coater, due to RTP process.

• Able to make TCO’s but not viable as produce FTO.



Comparison – SnO2:F vs ZnO:Al

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

• After etching AZO significantly enhances light scattering (for silicon devices)

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

• SnO2:F is cheaper and more durable than ZnO:Al



NSG Products



Coated Products

• Coated Products Divided into 3 groups;



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™ .

• 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%.




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







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.




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







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.



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



NSG TEC™ Glass Properties



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.



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.



Thin film silicon NSG TEC™A8 High haze, rough coating

TCO coating

Surface roughness

CdTe NSG TEC™C15 Low haze, smooth coating

TCO coating

Surface roughness

NSG TEC™ Glass Appliance Applications



Commercial Refrigeration and Freezer Applications

Passive Active Curved

NSG TEC™ Glass Appliance Applications



Commercial Food Warmers

Oven Door Glass

Touch Panel Technology - Resistive

• Resistive touchscreens use a flexible outer membrane that, upon user touch, forms an electrical circuit with the glass substrate.



Glass

TEC 1100 – High Resistance Coating

Resistive Coating

Protective Coating

Flexible Membrane

Insulating

Spacers

Glass

TEC 1100 – High Resistance Coating

Resistive Coating

Protective Coating

Flexible Membrane

Insulating

SpacersNSG TEC™

Touch Panel Technology - Capacitive

• Capacitive coupling between a conducting surface and the users finger draws current from the surface to determine the touch-point in capacitive screens.



Glass

TEC SB - Silica Layer

Conductive Coating – TCO (ITO or other)

sodium

Protective Coating

Glass

TEC SB - Silica Layer

Conductive Coating – TCO (ITO or other)

sodium

Protective Coating

NSG TEC™

Touch Panel Applications



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.



Heated Window Applications

• Residential Application – Exterior

• Photo and Application – Courtesy of Radiant Glass Industries LLC




• Residential Application – Interior

• Photo and Application – Courtesy of Radiant Glass Industries LLC




• Restaurant Application - Mahogany Grille, Durango Colorado

• Photos and Application – Courtesy of thermique™



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)



Industrial Transportation



NSG TEC™ Glass in Electrochromics

• Increasing activity in large area commercial electrochromic development

• 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.



Electrochromic Applications

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



• 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.



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.



Thank you for you attention

transparent conducting oxides - from and industrial perspective

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