Processing and Properties of V

CuInGaSe

2 (CIGS) Solar C

Kannan Ramanathan, Rommel Noufi

Bobby To, Raghu Bhattacharya, Mig

Ramesh Dhere, Glenn Teeter, Craig 

Sally Asher

National Center for Photovoltaics, N

NREL/PR-520-39888Presented at the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion (Win Waikoloa, Hawaii.
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• Thin Absorber grown by 3-stage • Growth from Cu-rich CGS or CIG• Solar cell results• Comparison of thin and thick cel• Conclusions
• Cost of Indium is a concern in hig

production.

• Thickness has an impact on cost, • It should be possible to make effic

cells with sub-micron absorbers.

Need to study v
• IEC, Matsushita performed parametric s

absorber thickness

• Ångstrom Solar published comprehensiv

O. Lundberg, Prog. PV 11, 77 (200

16% @ 1.8 μm, 15% @ 0.8-1 μm, 12% @ • M. Gloeckler and J. Sites, J. Appl. Phys. 

(2005)
60

5040302010

0

Atomic concentration (%)

5 10 

3-stage process 

543210

Rates (/s)

10 20 30 40

Run time (min)

Ga

Cu

In

Elemental flux vs. time Auger 
SEM 

1.2 μ 1 μ
5

43210

Rates (/s)

14 16 18 20 22 24 26 28 30

Run Time (min)

In

CuGa

Co-deposition o

605040302010

0

Atomic concentrations (%)

10

S

Elemental flux vs. time Auge
Co-depositio

Cu/(In+Ga) = 0.91Ga/(In+Ga) = 0.30

Cross section Pl
0.75 μm (12.5%) 0.4 μm 

Sub
Best result f

For 1 μm cA/cm

2, n = 

Values for cells: n = 1A/cm

2

Increase in 

accounts foshortfall. 
50

40302010

Atomic Concentration (%) 0

10

0

Sp

5040302010

Atomic concentration (%) 0

100

20

40

60

800

Sputter Time (sec)

Auger 

2.5-μm cell 1
Q

100

80604020

Absolute External QE (%)

1000

400

600

800

Wavelength (nm)

 1 μm cell, Jsc: 33.3 mA/cm2 Thick cell, Jsc: 31.9 mA/cm2
1.00.80.60.40.20.0

Cu or Ga mole fraction

20

40

60

Sputter time (sec)

Ga/III

Cu/III

1-μm cell 2.5-μm ce
Carrier concentration & 
t (μm) Voc

(V)

Jsc (mA/cm2) FF (%

1.0 (3 stg) 0.678 31.93 79.2 1.0 (codep) 0.699 30.6 75.4 0.60 0.658 26.1 73.1 0.40 0.565 21.3 75.7 Control 0.701 34.6 79.7 

Summa
• Three-stage process applied to micron tlayers. Best result of 17.1%. Most of the laccounted for. Voc reduction is the primar

• Co-deposition and Boeing process were successfully to grow submicron films. Effibe maintained down to 0.6 μm (12.5%).• Greater effort needed to understand crydiffusion, interfacial reactions and control • Thin cells can benefit from light trapping window layers. Efficiency can be increase
A

H.S. UllalB. Von RoedernK. ZweibelJ.C. KeaneX. WuT.J. CouttsS. Demtsu