37
Applied Materials External Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS BY CAPACITIVE COUPLED PECVD Yi Zheng, Alan Tso, Fan Yang, Rongping Wang, Tom Tanaka, Ned Hammond, Lin Zhang, Zheng Yuan and Brian Shieh Thin Film Solar Products Division, Applied Materials, Santa Clara, CA 95054 AVS PAG Meeting AVS PAG Meeting

UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

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Page 1: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS BY CAPACITIVE COUPLED PECVD

Yi Zheng, Alan Tso, Fan Yang, Rongping Wang, Tom Tanaka, Ned Hammond, Lin Zhang, Zheng Yuan and Brian Shieh

Thin Film Solar Products Division, Applied Materials, Santa Clara, CA 95054

AVS PAG MeetingAVS PAG Meeting

Page 2: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

2

Types of Solar Cells

Crystalline Silicon– Monocrystalline, Multicrystalline, Ribbon, etc.

Thin Films– Amorphous and crystalline silicon– Cadmium Telluride (CdTe)– Copper Indium Selenide (CIS, CIGS)

Concentration– Silicon, multi-junction III-V, thermophotovoltaic

Emerging Technologies– Organic materials, Nanostructures, etc.

Crystalline Si and Thin Films dominate market today

Page 3: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

3

NREL Cell Efficiency Map

Thin Film Efficiencies Rapidly Advancing

Page 4: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

4

PV Module Price Reduction

$1

$10

$100

1 10 100 1,000 10,000 100,000 1,000,000Cumulative Production (MWp)

Mod

ule

Pric

e (2

006

$/W

p)Historical Prices

1980

2007e

$3.98/Wp

$1.00/W @ ~300 GWp

$1.00/W @ <20 GWp

Thin Film2007e

c-Si

Source: Adapted from NREL;Historical data from Navigant Consulting

Module price decreases 20% for every 2x production increase

2003$3.53/Wp

1995$6.88/Wp

1985$12.01/Wp

1982$18.73/Wp

Page 5: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

5

Thin-film Advantages and Disadvantages

Advantages

CIS– Highest thin-film efficiencies– Good cell stability– Good product appearance

CdTe– High deposition rate– Proven large-volume mftg– Current low cost leader

Si– Well-known Si-based PV science– Multi-junctions for high efficiency– Large-area, large-volume mftg

Disadvantages

CIS– Mftg yield and volume– Indium price / availability– Field durability

CdTe– Mftg and product restrictions (Cd)– High-temperature process– Absorber thickness ; Te availability

Si– Single-junction efficiency– Deposition rate– Multi-junction mftg control

Page 6: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

6

Leading Thin Film PV Technologies

Ag/AlZnO:Al

a-Si

Low Iron Glass Superstrate

doped Si

SnO2 :F, ZnO:Al

Barrier

µc-Si

Mo

CIGS

CdS

Soda Lime Glass Substrate

i-ZnOZnO:Al

Barrier

TF Si CIGS

Back Metal

CdTe

CdS

Soda Lime Glass Superstrate

SnO2 :F

Barrier

CdTe

Back Material

Page 7: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

7

Thin Film Technology Comparison

CIGS CdTe TJ a-Si/uc-SiModule Size (m2) ≤ 0.72 m2 ≤ 0.72 m2 1.43m2, 2.86m2, 5.72m2

Stabilized Module Efficiency Today 8-12% 10% 8%

Stabilized Module Efficiency Roadmap to 2010

15% 12% 10%

Best Laboratory Cell Efficiency 19.5% 17% 13.5%

Temperature Coefficient, Power -0.36 % / °C - 0.25 % / °C - 0.2 % / °C

Raw Materials for PV 3 – 5 GW annual (limited Indium increases

cost)

3 – 5 GW annual (limited Telluride

increases cost)Unlimited Si supply

Volume Production Ramp Readiness

Material, uniformity, t-put, equipment maturity,

etc.In volume production In volume production

Module Reliability Limited field data impacts financiability

Limited but growing field data a-Si >20 years

Production Cost / Wp in 2010

No volume production cost data <$1.00 /Wp <$1.00 /Wp

Applications Rooftop, BIPV Solar Farms, Rooftop, BIPV

Solar Farms, Rooftop, BIPV

*Sources: NREL, Deutsche Bank, USGS, Photon International

Page 8: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

8

Thin Film Si PV Cell - Single Juction & Tandem Junction

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

20

0

40

60

80

100

0

1

2

3

4

5

Num

ber o

f Sun

light

Pho

tons

(m-2

s-1 m

icro

n-1 )

E+19

Rel

ativ

e Ex

tern

al Q

uant

um E

ffici

ency

, %

c-Si:H junctiona-Si:H junction

AM 1.5 global spectrum

Wavelength, microns

~2 µm

a-Si Single Junction

a-Si/µc-Si Tandem Junction

AgTCO

n

p

i

n

p

i

~2-3 µm

Glass Substrate

Transparent Conductor

Amorphous Silicon

Microcrystalline Silicon

Back Contact

AlTCO

n

p

i

Glass Substrate

Transparent Conductor

Amorphous Silicon

Back Contact

thin a-Si

µc-Si

back contact

a-Si:H/µc-Si:H advantages

Low-cost Better temperature

stabilityBetter diffuse light

efficiency Paths to higher CE

a-Si:H/µc-Si:H challenges

Large area film uniformity

High equipment cost Low dep rateLow CE

Page 9: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

9

AppliedApplied’’s Tool Boxs Tool Box

Baccini*Baccini*

SiliconSystems

Advancing Technology Innovating Productivity

DisplayBusiness

Delivering NewTechnology and Scale

Energy & Environmental

SolutionsChanging the

Energy Equation

Fab SolutionsDriving Fab Productivity

Thin Film Crystalline

Page 10: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

10

ACLS

25K / 25KA1500x1800 1500x1850

27,750 cm2(1.78 from 15 K)

5/ '03~

Gen 6Gen 5.5

19,500 cm2(1.25 from 15 K)

20K 1300x1500

ACLS

8/ '04~

Gen 8

ACLS

50K 2160x2400 class

53,136 cm2(1.21 from 40 KA)

2006

Panel sizeInch

10.4 12.1 15 ~ 17 19 ~ 23 21 ~ 24 46W37W32W 52W

Panel/sub 4 6 6 6 6 666 6

Application Note PC -----------------> Monitor TV ----------------->

1600370x470400x500

3500 / 4300 / 4300A550x650600x720620x750

5500/5500A680x880730x920

10K1000x1200

15K / 15KA1100x12501200x1300

Substrate Area

2,000 cm2(1.00)

4,650 cm2(2.33 from 1600)

6,716 cm2(1.44 from 4300)

12,000 cm2(1.79 from 5500)

15,600 cm2(1.30 from 10K)

40K / 40KA1870x22001950x2250

41,140 cm2(1.52 from 25 K)

ModelSubstrate Size (mm)

Gen 2 Gen 3 / 3.5 Gen 4 Gen 5 Gen 5 Gen 7 / 7.5

System Layout

ACLS ACLS

2/ '93~ 4/ '95~ 1/ '00~ 8/ '01~ 6/ '02~ 7/ '04~1st Release

4 up 10.4”

6 up 12.1”

6 up15.0” ~ 17.0”

6 up19.0” ~ 24.0”

6 up37.0” Wide panels

6 up46.0” Wide panels

6 up52.0” Wide panels

2160x2460

AKT PECVD Size EvolutionAKT PECVD Size Evolution

Our demonstrated capability in large area TFT-LCD tools

Page 11: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

11

SunFab Value Proposition – 12 Lines Worldwide

Module Right Sizing Advantage & Flexibility– Flexible panel size (¼, ½, and Full Size) serves multiple markets: residential rooftop, commercial

rooftop, BIPV, and utility scale– SunFab full size panel (5.7m2), world’s largest, delivers the highest power out per panel 560Wp

Leading Technology– High Efficiency Tandem Junctions, Better Energy Harvest due to lower temperature coefficients– High-speed, high-yield processing of thin glass substrates (2.2x2.6m)

Fastest to Scale– World class equipment serves as foundation for Factory performance– <6 months from factory ready to Volume Production

Cost

Watts

Applied SunFab Gen 8.5 PECVD

Full Size SunFab Panel

560 Wp

¼ Size

Page 12: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

12

PECVD chamber structure

Process gases:– SiH4 , H2– Dopants (C3 H9 B for p-doping and

PH3 for n-doping)– Single gas feed through at the

center of the chamber lid

Diffuser:– Distribute gas flow– RF electrode– Proprietary hallow cathode design

Enhanced gas dissociation

Uniformly dissociated reactant gases

Susceptor– Multiple heating and cooling zones

Ensure temperature uniformity– RF ground

Slit valve for substrate loading / unloading

RF power supply

Gas feed

To pump

Slit valveObservation window

SusceptorGlass substrate

Diffuser

Page 13: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

13

Big Challenge - 5.7m2 Substrate µc-Si Filmamorphous phase at corners

20

30

40

50

60

70

80

0 500 1000 1500 2000 2500Distance (mm)

fc (%

)

Crystalline fraction along diagonal

Amorphous Microcrystallinea-Si due to lower power density

Result is lower cell Jsc & FF

Page 14: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

14

Silane concentration, power, frequency, temperature, ...Decreasing crystalline volume fraction

stationarycolumnar growth

incubation zone

substrate

voidsamorphous regionscrystallites

several100 nm

~30-50 nm

PorousCracks/columns

in TEMHigh

spin

densityBad solar cells

Compact Cracks/columns

in TEMLow spin

densityGood solar cells

Structure of µc-Si:H

Page 15: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

15

Parameters that Affect Film Uniformity

Plasma Uniformity

Gas Flow Distribution

Pumping Mechanism

Susceptor

Spacing

Diffuser Gas Flow

To pump

Page 16: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

16

Plasma Uniformity - Proprietary Electrode Design

0

100

200

300

400

500

-1250 -750 -250 250 750 1250Distance from Edge (mm)

Thic

knes

s (n

m)

Gen 5

Gen 6

Gen 7

Gen 8

Gate Insulator quality SiNx film

Uniformity: < +/- 10%

0500

10001500200025003000

0 500 1000 1500 2000

Distance (mm)

Dep

o. R

ate

(A/m

in)

Before standing wave correction

Susceptor

Diffuser Profile Change

Page 17: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

17

Chamber Flow Simulation

Chamber pumping flow simulation indicated non-uniform flow distribution

Page 18: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

18

Full Size 5.7m2 uc-Si Film

20

30

40

50

60

70

0 500 1000 1500 2000 2500

Distance (mm)

f c(%

)

µc-Si layer with LCD Hardware Crystalline Fraction (fc )

• a-Si deposition in the corners due to lower power density

• Result is lower cell Voc & FF

µc-Si layer with New Hardware TJ Cell Efficiency & Jsc

0

2

4

6

8

10

12

0 500 1000 1500 2000 2500

CE

(%

), J s

c(m

A/c

m2 ) CE

Jsc

• New Hardware improved uniformity and crystalline fraction

• Results in better homogeneity and higher efficiency

Page 19: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

19

0

50

100

150

200

250

300

350

400

450

500

0 400 800 1200 1600 2000 2400

X (mm)

Dep

Rat

e (A

/min

)

Two Remaining Issues:

40

45

50

55

60

65

70

75

80

0 400 800 1200 1600 2000 2400

X (mm)Fc

(%)

TL to BRBL to TR

Thickness Across PanelThickness Across Panel Crystalline Fraction Across PanelCrystalline Fraction Across Panel

2600 mm

2200

mm

5.7 m5.7 m22

• Asymetry of uc-Si Crystalline Fraction Uniformity • Corner low dep rate

• Asymetry of uc-Si Crystalline Fraction Uniformity• Corner low dep rate

Page 20: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

20

Balance the Plasma – Unbalance the Feed

(a) (b)

RF field intensity w/ original RF feed

RF field intensity w/ displaced RF feed

RF power supply

Slit valveObservation window

-1000-50005001000

-1000

-500

0

500

1000

Mean = 128.3, NU = 49.3%

213

72

100

150

200

Page 21: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

21

0

50

100

150

200

250

300

350

400

450

500

0 400 800 1200 1600 2000 2400

X (mm)D

ep R

ate

(A/m

in)

0

50

100

150

200

250

300

350

400

450

500

0 400 800 1200 1600 2000 2400

X (mm)

Dep

Rat

e (A

/min

)

RF Fee Location Effects on mc-I Thickness and Fc Uniformity

Unif: 17.8% Unif: 7%

40

45

50

55

60

65

70

75

80

0 400 800 1200 1600 2000 2400

X (mm)

Fc (%

)

TL to BRBL to TR

40

45

50

55

60

65

70

75

80

0 400 800 1200 1600 2000 2400

X (mm)

Fc (%

)

TL to BRBL to TR

0

50

100

150

200

250

300

350

400

450

500

0 400 800 1200 1600 2000 2400

X (mm)

DR

(A/m

in)

Unif: 5%

BKM RF Feed RF Feed Rev1 RF Feed Rev2

40

45

50

55

60

65

70

75

80

0 400 800 1200 1600 2000 2400

X (mm)

Fc (%

)

TL to BRBL to TR

Rev2 RF Feed improved thickness and fc uniformity

Page 22: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

22

Good correlation between simulation and experiment

Local RF Density Enhancement – GroundingApproach: modify grounding configuration to modulate the electrical field at corners.

Delta: Ground Strap Rev4 - BKM (SF BKM5)

Thickness delta map

(Experiment)

g-20 - -17.9

-17.9 - -15.8

-15.8 - -13.7

-13.7 - -11.6

-11.6 - -9.5

-9.5 - -7.4

-7.4 - -5.3

-5.3 - -3.2

-3.2 - -1.1

-1.1 - 1

1 - 3.1

3.1 - 5.2

5.2 - 7.3

7.3 - 9.4

9.4 - 11.5

11.5 - 13.6

13.6 - 15.7

15.7 - 17.8

17.8 - 19.9

19.9 - 22

22 - 24.1

24.1 - 26.2

26.2 - 28.3

28.3 - 30.4

30.4 - 32.5

32.5 - 34.6

34.6 - 36.7

36.7 - 38.8

38.8 - 40.9

40.9 - 43

43 - 45.1

45.1 - 73.1

Corner thickness increase

Thickness delta map

(Simulation)

Corner RF straps removed

Page 23: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

23

Uniform uc-Sicoating

Uniform Large-Area uc-Si Film

Unif: 5% (1s, 400pts)

Page 24: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

24

a-Si:H single layer uniformity change

With original RF feed– Average thickness 390 nm– Standard deviation of thickness,

t = 20 nm– Non-uniformity = 4.3%

After modifying the RF feed location– Average thickness unchanged– t = 21nm– Non-uniformity was 3.2%

Insignificant change in thickness profile and uniformity Sl

it va

lve

minmax

minmax (NU) uniformity-nontttt

0

100

200

300

400

500

600

700

800

0 500 1000 1500 2000 2500

Distance (mm)

a-Si

thic

knes

s (n

m)

Original RF feedModified RF feed

win

dow

Slit

val

ve

Page 25: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

25

010

2030

405060

7080

90100

0 500 1000 1500 2000 2500

Distance (mm)

FF (%

)

Original

RF Rev 1

0

2

4

6

8

10

12

14

0 500 1000 1500 2000 2500

Distance (mm)

Jsc

(mA

/cm

2 )

Original

RF Rev 1

0.6

0.7

0.8

0.9

1

1.11.2

1.3

1.4

1.5

1.6

0 500 1000 1500 2000 2500

Distance (mm)

Voc

(V)

Original

RF Rev 1

Solar cell performance uniformity

Uniformity of Jsc– Improved from 7.9% to 2.9%

Uniformity of Voc– Improved from 4.8% to 3.3%

Uniformity of FF– Improved from 5.8% to 4.1%

Legend RF feed NU (%)

Original 7.9

Modified 2.9

win

dow

Slit

val

ve

win

dow

Slit

val

ve

Legend RF feed NU (%)

Original 4.8

Modified 3.3

win

dow

Slit

val

ve

Legend RF feed NU (%)

Original 5.8

Modified 4.1

Page 26: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

26

Development of High Dep Rate uc-Si ProcessesConventional Approach [1]

High H2 dilution ratio, R~100High total flowMedium RF power (0.5~0.7W/cm2)

ResultsGood cell efficiencyMedium deposition rateLarge area

[1] B. Rech, etc., Solar Energy Materials & Solar cells 66 (2001) 267-273.

Conventional Approach [1]

High H2 dilution ratio, R~100High total flowMedium RF power (0.5~0.7W/cm2)

ResultsGood cell efficiencyMedium deposition rateLarge area

[1] B. Rech, etc., Solar Energy Materials & Solar cells 66 (2001) 267-273.

Pure Silane Approach [2]

Zero H2 dilution ratio, R=0Very low total flowSmall RF power

ResultsGood cell efficiencyMedium deposition rateSmall area

[2] M. N. Donker, etc., J. Mater. Res., Vol. 22. No. 7, Jul 2007.

Pure Silane Approach [2]

Zero H2 dilution ratio, R=0Very low total flowSmall RF power

ResultsGood cell efficiencyMedium deposition rateSmall area

[2] M. N. Donker, etc., J. Mater. Res., Vol. 22. No. 7, Jul 2007.

Compromising ApproachLow H2 dilution ratio, R~30Medium total flowHigh RF power

ResultsGood cell efficiencyHigh deposition rateLarge area

Compromising ApproachLow H2 dilution ratio, R~30Medium total flowHigh RF power

ResultsGood cell efficiencyHigh deposition rateLarge area

CO

MPR

OM

ISING

CO

MPR

OM

ISING

Page 27: UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION THIN FILM SOLAR CELLS … · 2017. 6. 9. · Display & SunFab Solar UNIFORM GROWTH OF LARGE AREA a-Si / c-Si TANDEM JUNCTION

Applied Materials ExternalDisplay & SunFab Solar

27

Film properties at high deposition rate

Raman,

XRD

Stress

Conductivity

TEM shows clear column structure, which agrees with XRD and Raman

measurement.

TEM shows clear column structure, which agrees with XRD and Raman

measurement.

20 25 30 35 40 45 502 Theta (degree)

Inte

nsity

(a.u

.)

(220)

(111)

(220) / (111) = 2.1(220) / (111) = 2.1

380 430 480 530 580Raman shift (cm-1)

Inte

nsity

(a.u

.)

Experimental dataa-SiGrain boundaryc-SiTotal

Fc = 55.6%Fc = 55.6%

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IV and QE performance comparison

The high deposition rate one (HD with DR=660A/min) have initial IV performance comparable to its reference with DR=400A/min.

All the data shown is taken 6 months after cell fabrication, high deposition rate ones show stable performance same as reference.

LID (two sun light intensity, 300 hours, 50˚C) performance is the same for high deposition rate and its reference. (Data not showing here.)

The high deposition rate one (HD with DR=660A/min) have initial IV performance comparable to its reference with DR=400A/min.

All the data shown is taken 6 months after cell fabrication, high deposition rate ones show stable performance same as reference.

LID (two sun light intensity, 300 hours, 50˚C) performance is the same for high deposition rate and its reference. (Data not showing here.)

Same top cell QE response for all the cells. No obvious damage/change to top cell under high deposition rate for bottom cell I layers.

High deposition rate bottom cells have QE response comparable to its reference.

Same top cell QE response for all the cells. No obvious damage/change to top cell under high deposition rate for bottom cell I layers.

High deposition rate bottom cells have QE response comparable to its reference.

0

10

20

30

40

50

60

70

80

90

100

300 500 700 900 1100Wavelength (nm)

QE

(%)

ReftopHDtopRefbotHDbot

0

2

4

6

8

10

12

0 0.25 0.5 0.75 1 1.25 1.5Voltage (V)

Cur

rent

den

sity

(mA

/cm2 )

RefHD

Initial IV performance

CE (%)

FF (%)Voc (V)

Jsc (mA/cm2)

Parameters10.7

71.51.33611.2

HD10.7

71.71.37910.8

Reference

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SunFab: Unlocking Cost ReductionSunFab: Unlocking Cost ReductionSunFab Solar Projected Output

60 MWp (TJ) per year

0.75 km2 of panels per year

5.7m2 panels – largest in the world

>20,000 homes (3kWp each)

$1/Watt Production Cost 2010

0.72 km2

Forbidden City Beijing China

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JapanJapanChinaChina

IndiaIndia

BrazilBrazil

S. AfricaS. Africa

Southern Southern EuropeEurope

GermanyGermany

Middle EastMiddle East

AustraliaAustralia

NorthNorthAmericaAmerica

1min of Solar energy > 1 year of world energy consumption

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3333

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Cell to Cell Connection

Front Glass

Front TCO

a-Si p-i-n

Back Reflector (Back TCO and Metal)P1 Scribe

P2 ScribeP3 Scribe

Active Area

Scribe Loss Area

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End Scribe

P1 Scribe

P2 Scribe

Bus Bar(–)

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Light trapping

Incoming Light

Front Glass

Front TCO

n-Type a-SiIntrinsic a-Sip-Type a-Si

Back TCOBack Metal

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c-Si:H layer uniformity change

No significant thickness change

Fc: crystalline fraction– Calculated from film Raman

absorption spectrum– Raman condition:

Laser wavelength = 532 nm

Temperature = -49 C– fc is defined as:*

With modified RF feed– fc non-uniformity significantly

improved from 8.5% to 3.0%

ac

c

II

Ifc

250100exp1.0

100

250300350400450500550600

Raman shift (cm-1)

Measured

Ram

an a

bsor

ptio

n in

tens

ity ,

a.u.

IcIa

* R. E. I. Schropp and M. Zeman, Amorphous and microcrystalline silicon solar cells, Kluwer Academic Publishers, 1998

0

10

20

30

40

50

60

70

80

0 500 1000 1500 2000 2500

Distance (mm)

fc (%

)Series1

Series3

Legend RF feed NUfc (%)

Original 8.5

Modified 3.0

win

dow

Slit

val

ve