Habilitation presentation 2011

1

Habilitation à Diriger de Recherches. Veronica BERMUDEZBENITO16 June 2011. université AixMarseille. IM2NP16/07/10

Copyright © NEXCIS – Tous droits réservés

NEXCIS Business Development

Draft V2, 13th September 2010

Habilitation à Diriger de Recherches

Veronica BERMUDEZBENITO

16 June 2011

2

Habilitation à Diriger de Recherches. Veronica BERMUDEZBENITO16 June 2011. université AixMarseille. IM2NP

1. Summary

1. Why we are here?

2. State of the Art of Thin Film Solar cells

3. Research Project

1. Why choosing CIGS

2. Closing the gap

3. In(situ characterization

4. Previous Activity

1. Lithium Niobate

2. Periodic Poled Lithium Niobate

3. CdTe for PV

4. Modelling and Characterizing CIGS devices

5. Some indicators

Agenda

3



Thin Film Solar Cells for future

4


Why thin films in the future:

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2005 2010 2020 2030 2040 2050

Ma

rke

t Sh

are

Novel devices

Other thin films

Thin films

Silicon thin films

Crystalline Si

Thin Films> 15% in 2010 45% in 2020

Source: IEA 2010

Forecast from IEA (BLUE Map) in 2030 : towards a mix of technologies

5


Advantages of thin film PV

• Efficient and high performing materials

• Direct bandgap semiconductors

• Better energy output – kWh/KW

• CIGS record at 20%+ conversion efficiency

• Significantly reduced costs

• Less material usage

• Potential for improving costs throughout value chain

• Better aesthetics

• Roadmap of glass3to3glass and flexible substrate

6


Solar Today

Google HQ -Solar ProjectSolar farm in Amstein, Germany

Utility Scale Commercial Systems

7


Solar Tomorrow: Building Integrated Photovoltaics

Power Buildings will become multi-$T market• BIPV is the fastest growing sector of PV• Building Integration leverages available surface area,

installation costs, and proximity to loads

Revolutionary products through efficient, durable thin-film solar cells embedded into traditional building materials

• Current products unsuitable and not cost effective

8


BIPV Applications

• Roofing

• Most common BIPV application today

• Sunshades

• Energy conservation and reduced building operating costs

• Cooling load mitigation and glare control

• Easiest retrofit for PV

• Overhead glazing (canopies,

skylights, atriums)

• Curtain wall / Facades

9



Between thin films Why CIGS?

10


State of the art in efficiency. Big gap between R&D and production

Who? Device Aperture Area Efficiency

Würth Solar CIGS (glass) 6500 13.0

AVANCIS CIGSS (glass) 4938 (26 x 26) 13.0 (15.5)

Solar Frontier CIGSS (glass) 3600 (30 x 30) 13.0 (17.2)

Solibro CIGS (glass) 6840 14.2

Global Solar CIGS (flexible) 8390 (3822) 10.5 (13.0)

Miasole CIGS (flexible)* > 1 m2 15.7

Solopower CIGS (flexible) 0.3m x 2.9m 12.0

First Solar cdTe (glass) 6623, high volume 11.3 (12.6)

* Sandwiched between two pieces of glass

Device/ Module Type Efficiency (%) Who?

Cells (0,5 – 1 cm2) > 18 to 20.3* NREL, ZSW, AIST, HZB, AGU, ASC

Submodules (20 – 100 cm2) 15- 17* ZSW, ASC, HZB, Showa Shell

Prototype modules (0,35 – 0’7 m2)

13 – 16* Solar Frontier, Miasolé, Global Solar, Avancis

Commercial Modules (0,7 m2) 12-13 Würth Solar, Solibro, Global Solar, Solar Frontier, Avancis

11


Closing the gap between record efficiencies and commercial modules

Target 15%

6%

12%

20.3%

23%

Lab device

Challenging target

Closing the gap

Expanding Tech. Base

Closing the gap

Improvement of fundamental materialknowledge

Derive measurable materialproperties that are predictive of device and module performance

Model the relationshipbetween film growth and material delivery

Industrial processes, beneficial impacts:

( higher throughput and yield( higher degree of reliability and reproductibility( higher module performance

In(Situ ProccesDiagnostics and Control

Better science(basedknowledge of materials properties

Materials and photonicinteralation. Real time diagnosis tools.

12


CIGS based devices. Facing the challenge

SCR

- Charge carriers are generated in absorber layer.

-Limited, by the absorber bulk quality, and electronic quality

of the absorber related interfaces.

-After charge separation at p-n junction, recombination

currents will dominate the transport, relaxing the impact of

other interfaces.

- More than 80% of performance losses is related to absorber

quality.

13


Crystal structure of Cu(In,Ga)Se2 –chalcopyrite3type3

Elemental

Binary

Ternary,…

DiamondSi, Ge

Zincblende

WurziteCdTe, GaAsChalcopyriteCu(In,Ga)(S,Se)2

14


Cu3(In, Ga)3Se Ternary Alloys Molecularity (M) and Stoichiometry (S)

M = [Cu]/([In] + [Ga])

S = 2[Se]/ ([Cu] + 3([In]+[Ga]))

∆∆∆∆M = M (1; ∆∆∆∆S = S – 1

ALL high efficiency

CIGS devices have

∆∆∆∆M < 0 and ∆∆∆∆S > 0

Formation reaction

yCu2Se + (13y) (In,Ga)2 Se3+∆∆∆∆Se Cuy ((In,Ga)13y)2 Se332y+∆∆∆∆Se

Se

Cu In, Ga

Intermetallic Plethora

(In,Ga)2 Se3

(In,Ga) Se

(In,Ga)4 Se3

Cu2 Se

Cu Se

Cu2 Se3

112247

135

112 = CuInSe2

247 = Cu2In4Se7

135 = CuIn3Se5

15


CIGS Complex Non3Stoichiometric Thermochemical Phase Structure

S. Yamazoe, H. Kou and T. Wada, J. Mater. Res., in press.

16


Compositional Fluctuations and Carrier Transport in CIGS absorbers

Experimental results HAADF(TEM and Nanoscale EDS

(5(10 nm chracteristic domain size(Chemical composition fluctuations across the domains

p1: Cu:In:Ga:Se = 31:14:7:48p2: Cu:In:Ga:Se = 27:15:9:49p3: Cu:In:Ga:Se = 30:15:6:49

(Dark domains are relatively Cu rich, bright domains are relatively Cu poor.

JB Stanberry et al. APL 87, 2005, 121904

HAADF(TEM: High(Angle Annular Dark(Field Transmission Electron MicroscopyEDS: Energy(Dispersive X(Ray Spectroscopy

17


CIGS Non3Stoichiometry and Atypical Device Behavior

• Peculiar semiconductor behavior:

CIGS PV devices insensitive to % atomic composition variations & extended defects

>19% efficiencies recently reported† over range:

• 0.69 ≤ [Cu]/([In]+[Ga]) ≤ 0.98 (Group I/III ratio)

• 0.21 ≤ [Ga]/([Ga]+[In]) ≤ 0.38 (Group III alloy ratio: Eg

• Empirical Observations

• CIGS PV devices are always copper deficient compared to α(CuInSe2

• Compositions lie in the equilibrium α+β2(phase domain

†Jackson et al., Prog. PV, Wiley & Sons, 2007.

18


Characteristics of an Ideal CIGS Manufacturing process and state of the

art of CIGS synthesis

• CIGS Manufacturing method should provide a high device(quality material

• Ability to create intrinsic defect structures limiting recombinations; role of order(disorder transitions?

• Ability to control Group III(VI composition gradients

• Control of extrinsic doping

• Low high processing Rates

• Low thermal budget

• High materials utilization

Process Steps, precursor Characteristics

Multistage coevaporation Binary chalcogenidecompounds

Reduction of Se utilisation and In incorporation

Reactive annealing pure metalfilms (PVD, plating…)

Sputtered metal or alloy films followed by high T annealingin Se/S

Complex intermetallicalloying. Uncontrolledsegregation

Reactive annealing Se/S containing precursors

Incorporate Se followed fromRTP

Multi-step reaction kineticsHelp Se in-diffusion

Reactive annealing particleprecursors

Printed particles followed by high T annealing in Se/S

Difficult recrystallizationkinetics

19


Intrinsic defects stronlgy affect optoelectronic properties. Growthconditions

20


Influence of Se overpressure and crystal orientation on the Luminescence and thus in electronic chraacteristics

P3

P2

P1

Manuel Romero Courtesy

21


The complexity of mechanisms and unexpected relations. Source materials and kinetics. Selenium case

Nominally same growth conditions, except Sesource:

( E( Se conventional evaporation Se target( R(Se rf(plasma cracked Se(radical beam

( Differences in Voc, FF and Jsc.

( Differences in Na and Ga step profile

( Differences in surface roughness, grain size and density of absorber.

Shogo Ishizuka, Akimasa Yamada, Hajime Shibata, Paul Fons, Shigeru Niki. Thin Solid Films, in press

22


The complexity of mechanisms and un expected relations. Source materials and kinetics. Selenium case

Shogo Ishizuka, Akimasa Yamada, Hajime Shibata, Paul Fons, Shigeru Niki. Thin Solid Films, in press

CdS is present at only near surface region of R(Se, while for E(Se depth profiles of Cd and S exhibit a broad distribution, due to presence of surface crevices.

Ga and Se diffuses at Mo/Mo interfaces for R(Se.

EBIC shows a more buried pn(junction in E(Se as pn(junction is formed in a deeper region near the Ga gradient valley according to SIMS.

R( Se E( Se R( Se E( Se

23


Difficulties in identifying in(situ/in(line measurable material properties

Closing the gap

Improvement of fundamentalmaterial knowledge

Derive measurable material propertiesthat are predictive of device and module performance

Model the relationship between film growth and material delivery

Industrial processes, beneficial impacts:

( higher throughput and yield( higher degree of reliability and reproductibility( higher module performance

In(Situ Procces Diagnostics and Control

Better science(based knowledgeof materials properties

Materials and photonicinteralation. Real time diagnosistools.

24



Previous activity

25


Education

Degree: Licence in Physics (5 years), obtained in 1996 at Autonoma University of Madrid (UAM)

Speciality in Optics and Materials Structure,

Master degree: Optics and Materials Structure, obtained in 1996 at AutonomaUniversity of Madrid

Subject: “Study and characterization of domain structure of LiNbO3”.

PhD Thesis Materials Science, obtained in 1998 at Autonoma University of MadridSubject: “ Obtention and Characterization of Periodic Structures in LiNbO3 single

crystals doped with Er e Yb”. Realized in the Crystal Growth Laboratory (CGL) of the Materials Physics

Department of the UAMThesis Director: Prof. Ernesto Dieguez

Highest qualification and Extraordinary Prize of the University for Thesis in Science.

26


Experience

1995(1998 PhD Thesis in the Crystal Growth Laboratory of Materials PhysicsDepartment at UAM (Spain)

1999(2000 Laboratory of Advanced Technologies (DEIN/SPE/GCO) at CEA(LETI inSaclay (France).European Postdoctoral fellow within Marie Curie Program in the 5th EU Program.

2000(2001 Materials Physics Department, Universidad Autonoma de Madrid (Spain)Post(doctoral fellow

2001(2006 Materials Physics Department, Universidad Autonoma de Madrid (Spain)Researcher in the Tenure Track “Ramon y Cajal” Program. Transformed to AssistantProfessor in 2005.

2005(2009 Institute for the Research and Development of Photovoltaic Energy (IRDEP)

EDF R&D, CNRS, ENSCP mix Institute, Chatou (France)Researcher, Project Manager and Optoelectronic Characterization Laboratory Head

2005(2007 as “Poste Rouge” in CNRS2007(2009 as Engineer(Researcher in EDF R&D

2009(present NEXCIS Photovoltaic Innovation, Rousset (France)Senior Scientist

27


Very Promising Basic Material Properties

Possibility of micro-controlling Properties by tailoring Composition and Doping

+

+Tailoring of Different Sample

Structures

A WIDE RANGE OF INTERESTING PHOTONIC APPLICATIONS

28


Peculiar trajectory

Ferroelectric domainsin Lithium Niobate

Doping to control domains and laser properties

Semiconductorsfor energy

Thin films for photovoltaicCdTe and CIGS

Closing the gap:

( Deep understanding( In line characterization

Molecularmotors

Based in understanding relationship

between:

3 Material physico3chemical properties

and growth (preparation) process and

history .

(Materials physico3chemical properties

and optoelectronic defect.

3 Defects and growth process and history

Missed in past:

Development of characterization

methods for process monitoring

as the way to control defects

formation. Photonics

29



Luthium Niobate and the way to fashion their ferroelectric domain structure for optoelectronic applications

30


Lithium Niobate a decathlon winner

LN structure has been described as a very distorted perovskite with a tilt rotation of the oxygen triangles around the c axis. Intrinsic defects at the origin of theirproperties

The chemical formula Li0.925(8)Nb1.07(1)O2.64(2) obtained during our work suggest the coexistence of lithium and oxygen vacancies; and their presence is strongly determined by the thermal history of the crystal.

48.4 mol% Li2OCongruent composition

31


Ferroelectric domains in lithium niobate

HF:HNO3 (1:2 by vol) at 110°C during 10 min.

19F mapping distribution by SIMS (skils adquiredduring my PhD stages in Padova University)

Ferroelectric Paraelectric

C(axis

32


Off centered Czochralski growth of PPLN and APPLN

Λ = 2 vpull/vrot

33


Stoichiometric LiNbO3 impacting properties

10 20 30 40 50 60 70 80 90 100 110

316.30

316.32

316.34

316.36

316.38

316.40

316.42

316.44

316.46

316.48

316.50

316.52

316.54

316.56

V(Å

3 )

Temperature (K)

Mínimos locales de Volumen de celda

0 20 40 60 80 100 120 140 160 180 200 220

0.9173

0.9174

0.9175

0.9176

0.9177

0.9178

0.9179

100 K

Spo

ntan

eous

Str

ain

Temperature (K)

58 K

Structural Anomaly in LN at 55K observed with Neutron diffraction, strongly related with stoichiometry

Λ

ΛΛΛΛtheory ΛΛΛΛexperimental Deviation

0wt% 6.63 6.63 0%

2wt% 6.63 3.2 48%

4wt% 6.63 2.55 39%

5.2wt% 6.63 2.05 30.9%

7wt% 6.63 ------

34


Controlling the colour and the intensity

Generation of 8 different wavelength from only one pump source

System based on a APPLN:Nd crystal

VR

Mirrors

Pump

R

B

VGVB

2

lC

G

( ) [ ]Ennxnn )()2/(%)21()()2/(2 '3'3

33

''' λλσλλλ −−Λ+−Λ=

Λ= Domain period

σ33 = Electro-optic coefficient

λ= Fundamental wavelength (SHG)

x % = duty cycle

35


Thin Films Solar cells based in II3VI compounds”

Cd(g) + Te2(g) Cd(g) + Te2(g) Cd(g) + Te2(g)

Cd(g) + Te2(g) Cd(g) + Te2(g)

Cd(g) Te2(g)

Bi2Te3-x

(s)

CdTe(s)

Subst.

Cd(g) Te2(g)

Bi2Te3-x

(s)

CdTe(s)

Subst.

Cd(g) Te2(g)

Bi2Te3-x

(s)

CdTe(

s)

Subst.Thermal process for the wiskersformation under VLS process.

Using this properties of Bi2Te3(CdTe co(evaporation in a controlled way it should be possible to obtain ordered arrays of hexagonal rod CdTe and thus to enhance performance of final electronic systems

C. M. Ruiz, E. Saucedo, O. Sanz and V. Bermúdez

Journal of Physical Chemistry., in press

36



Materials for Energy Conversion.Thin film solar cells

CdTeCu(In,Ga)(S,Se)2

37


CdTe: Bi. New intraband material?

Extremely high Jsc (26.31 mA/cm2) for 600 mV of Voc in the case of a CdTe:Bi device withconcentration at 1017 at/cm3.

1016

1017

1018

1019

104

105

106

107

108

109

1010

1011

undoped CdTe

Re

sis

tiv

ity

(ΩΩ ΩΩ

.cm

)

Bi conc (at./cm3)

First Principles study of Bi doped CdTethin film solar cells: electronic and optical properties Y. Seminovski et al. ETSI UPM, Madrid

38

Habilitation à Diriger de Recherches. Veronica BERMUDEZBENITO16 June 2011. université AixMarseille. IM2NP 38

Equivalent circuit ⇒⇒⇒⇒ separate each layer to identify different problems in process

Optoelectronic diagnostic of a serial resistance based problem. (Back diode)

CIS

CdS

ZnO

Mo

RC1

R//ZnO

Rjonction

R//Mo

MoS2

R?ZnO

RC2

RMoS2

Iph ID1 ID2

Rsh

RC4

RC3

Rsh2

IRCIS

CdS

ZnO

Mo

RC1

R//ZnO

Rjunction

R//Mo

Mo(Se,S)2

RZnO

RC2

RMoS2

Iph ID1 ID2

Rsh

RC4

Rc3

RDR

IR2 3 4 5 6 7 8

420

480

540

600

660

720 Voc Rs

eff(%)

Voc

(mV

)

0

2

4

6

8

10

12

Rs (O

hm/cm

2)

-20

-15

-10

-5

0

5

-200 -100 0 100 200 300 400 500 600

Experimental data sample D Fitted curve with reverse diode Curve without reverse diode

J(mA/cm2)

V(mV)

s

R

ph

R

J

ph

J IRI

IIn

I

IIn

kT

qV +

−−

−=

00

lnln

-1 .0 -0 .5 0 .0 0 .5 1.0 1 .5

0 .0

2 .0n

4 .0n

6 .0n

8 .0n

10 .0n

Cap

acita

nce(

F)

Vbias

(V )

16 11C -2 -3d 14 39-1 9-2 -4a 14 56-2 -3d 14 29-1 9-1 -1a

13.31.936.3376

12.53.448.6594

5.355.361.8603

4.39.069.8671

RSEffFFVoc

39


S at the origin of CuxSe and thus origin of the back diode through CuIn5S8

Cu(S,Se)

Before chemical etching

150 200 250 300 350 400 450 500

(3)

(2)

No

rm.

Int.

(a.u

.)

Raman shift (cm-1)

(1)

Cu(S,Se)

CuIn5S8

Cu(S,Se) grain

CIS grain

1,15 1,20 1,25 1,30 1,35 1,40 1,45 1,50 1,55 1,60 1,65 1,701

10

100

Rs

(max

)

2Se/(Cu+3In)

Rs increases significantly for m >1.3

Agrees with compositional range leading to formation of CuSe secondary phase

CuSe at back layer region likely leading to formation of secondary phases (CuS + CuIn5S8) degrading Rs

Experimental data for very high Rs values suggest relationship with presence of CuIn5S8

40


In situ monitoring techniques. Precursor composition monitoring

m

50 100 150 200 250 300 350

Cu-Se

Ram

an in

tens

ity (a

.u.)

Raman shift (cm-1)

Cu-Se

Se

OVC

CISe Problem: strong signal from H2O (aqueous electrolyte solution) in 100 – 250 cm(1 spectral range

Possibility to define optimal values of I(CISe) & I (Se +CuSe) corresponding to m ≥ 1.3 (in spite of high noise level)

in(situ detection of deviations of m below 1.3

1.1 1.2 1.3 1.4 1.5 1.6 1.7

60000

80000

100000

120000

140000

160000

180000

200000

220000

240000

260000

Inte

nsita

t Ray

leig

h (a

.u.)

2Se/(Cu+3In)

Decrease of IR at higher values of m: Possibility to detect deviations of m also

above optimal range of values

1,1 1,2 1,3 1,4 1,5 1,6 1,7

Inte

ns

ity

(S

e +

Cu

Se

mo

des)

2Se/(Cu+3In)

41


Excitation with laser probe from BWtek system (785 nm): quasi resonant

excitation conditions in S-rich CuIn(S,Se)2 alloy:

Reduction of tint in more than

one order of magnitude (down to

seconds)

Efficient excitation of several

modes (in addition to A1 peak)

200 300 400 500 600 700 800 900

E(L)/B2(L)

E(L)

A1

Inte

nsity

(a.

u.)

Raman shift (cm-1)

E(L)/B2(L)

2nd order

Alternative: Raman in quasiresonant conditions (matched to a given composition):

Case example: Analysis of composition of S rich CuIn(Sx,Se13x)2

42


Fitting of Intensity of E(L)/B2(L) mode at about 340

cm(1: exponential dependence of intensity of

bands on alloy composition

High sensitivity for detection of deviations of values of x in Srich alloys

65 70 75 80 85 90 95 100

0

20000

40000

60000

80000

100000

120000 y = A1*exp(x/t1) + y0 Chi^2/DoF = 1584241.43866R^2 = 0.99927 y0 4622.04913 ±941.66472A1 0.12088 ±0.05329t1 7.29108 ±0.23256

E(L

)/B

2(L

) in

ten

sit

y (

a.u

.)

[S] %

Case example: Analysis of composition of S rich CuIn(Sx,Se13x)2

200 300 400 500 600 700 800 900

[S] = 70%[S] = 77%[S] = 86%

[S] = 89%

[S] = 91%

Inte

nsity

(a.

u.)

Raman shift (cm-1)

[S] = 100%1/2

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000

inte

nsity

(a.

u.)

Raman shift (cm-1)

[S] = 100%

[S] = 78%

[S] = 89%

[S] = 77%

[S] = 70%

Moreover:

0,35 0,40 0,45 0,50 0,55 0,60 0,65

1,450

1,455

1,460

1,465

1,470

1,475

1,480

1,485

1,490

1,495

Exi

ton

posi

tion

(eV

)

Voc (V)

Voc tends to increase with EPL.

43


Coloured regions: possibility to obtain resonant excitation with different lasers

Extension to alternative quaternary CIGS based alloys

Matching excitation wavelength to Eg: possibility to assess composition of

Cu(In,Ga)(S,Se)2 alloys with different Ga/(In+Ga) and/or S/(S+Se) contents:

0,0 0,2 0,4 0,6 0,8 1,0

1,0

1,2

1,4

1,6

1,8

2,0

2,2

2,4

2,6

Gap

(eV

)

Ga/(In+Ga)

Laser

CuInSe2

1064nm976nm

785nm

512nm

671nm

488nm

633nmCuGaSe2

CuGaS2

CuInS2

44


NaCN etching

Removal Cu(S,Se) secondary phases

RTP recrystallisationunder selenising and/or sulphurising conditions

Cu(In,Ga)(S,Se)2

Electrodeposition

Metallic or CuInSe2precursors

CBD of CdS buffer layer

RF-sputtering of ZnO window layer

Electrodeposition based process

In3line/ in3situ: Raman scattering monitoring of ED3CIGS films and

processes

Identification of phases and alloys (chemical composition)

Monitoring of crystalline quality & Ga, S and Se incorporation

Assessment of NaCN etching (disappearance of Cu(S,Se) modes)

& CdS deposition

45


Photoluminescence set3up13 Spectroscopy: study of radiative defects and quality of material

Metzger and Repins, et al. Thin Solid Films 517 (2009) p.2360, and EMRS, May 2008

46


Photoluminescence set3up

23 Mappping: process control

CdS

ZnO

CISSe

47



Some indicators

48


Some numbers

1996 1998 2000 2002 2004 2006 2008 2010 20120

2

4

6

8

10

12

14N

um

be

r o

f P

ub

lic

ati

on

s, IS

I

Year of Publication

Total ISI papers: 99

Sum of Times Cited: 741

Average Citations per Item: 7.5 (6.1)

h(index: 13

Conference Proceedings: 30

Oral Presentations: 14

Invited presentations: 7

Keynotes: 1

3 Patents (submitted)

49


Awards

1) PhD Thesis Prize Universidad Autónoma de Madrid, 1998/1999

2) Finalist in “The EU Descartes Prize 2003” within the frame of the EuropeanProject “Molecules in Motion: hydrogen bond(assembled molecular machines (MOLS(IN(MOTION).

3) Young Prize 2004 in Science and Technology by Universidad Complutense de Madrid Foundation

4) 2007 Schieber Prize from International Organization on Crystal Growth. With invited Plenary Conference. http://www.iocg.org/“Engineered Periodic Poled Lithium Niobate Structures doped with RareEarth for multi self(frequency conversion “

50


Others

2 thesis co(supervised (1 France, 1 Spain)

7 Stages supervised in France and Spain.

14 Seminars in France, Italy, Belgium, Spain, Germany

Associate Editor of Journal of Renewable and Sustainable Energy

Expert for AERES and EU in FP7

Pormoting Women in Science and Engineering

51


We are just speaking of produced watts?

Habilitation presentation 2011

Technology

Transcript of Habilitation presentation 2011