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This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

Technology Transfer of the 

CIGS Technology from the 

Laboratory to the PVMC

Cooperative Research and 

Development Final Report

CRADA Number: CRD-12-496

NREL Technical Contact: Lorelle Mansfield

CRADA Report

NREL/TP-5J00-71838

July 2018
NOTICE

This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable 

Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding 

provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Solar Energy 

Technologies Office. The views expressed in the article do not necessarily represent the views of the DOE or the 

U.S. Government. This report is available at no cost from the National Renewable Energy Laboratory (NREL) at 

www.nrel.gov/publications.

This report is available at no cost from the National Renewable 

Energy Laboratory (NREL) at www.nrel.gov/publications.

U.S. Department of Energy (DOE) reports produced after 1991 

and a growing number of pre-1991 documents are available 

free via www.OSTI.gov.

Cover Photos by Dennis Schroeder: (left to right) NREL 26173, NREL 18302, NREL 19758, NREL 29642, NREL 19795.

NREL prints on paper that contains recycled content.
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

Cooperative Research and Development Final Report

In accordance with requirements set forth in the terms of the CRADA agreement, this document 

is the final CRADA report, including a list of subject inventions, to be forwarded to the DOE 

Office of Science and Technical Information as part of the commitment to the public to 

demonstrate results of federally-funded research.

Parties to the Agreement: U.S. Photovoltaic Manufacturing Consortium, Inc.

CRADA Number: CRD-12-496

CRADA Title: Technology Transfer of the CIGS Technology from the Laboratory to the PVMC

Joint Work Statement Funding Table showing DOE commitment:

Estimated Costs NREL Shared Resources

a/k/a Government In-Kind

Year 1

Year 2

Year 3

Modification #1

Modification #2

Modification #3

$100,000.00

$100,000.00

$100,000.00

$867,157.00

$12,167.00

$91,000.00

TOTALS $1,270,324.00

Abstract of CRADA Work:

PVMC, Inc. (PVMC) and Contractor (NREL) will work together under a CRADA, through a 

distinct statement of work (SOW) for each project. Each SOW will be negotiated as a 

modification of the CRADA between PVMC and NREL with a principal investigator (PI) 

identified by the contractor so as to define specific tasks and funding that reflect the scope and 

objectives of that project. Projects will focus on extended collaborations with well-defined, longterm goals that are mutually beneficial to PVMC and NREL. Projects under the CRADA may 

fall within the areas listed below in the summary of research results, calling upon the NREL 

capabilities and expertise.

Modification 1: The first year of the CRADA will involve training PVMC personnel in the 

deposition process of the layers in the CIGS device based on the evaporation process, 

characterization methods used to track the properties of the films, device fabrication and 

integration of the layers into device compatible with the PVMC approach, and use standard exsitu characterization tools, and standard and novel in-situ metrology tools for process 

characterization to insure that the unit films in the MDF facility have the properties defined 
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

above in the unit step evaluation. The scope of the CRADA statement of work is based on 

knowledge already in the literature and/or in background published IP.

Modification 2: NREL loaned Ocean Optics spectrometer to PVMC. This was returned on 

2/15/2018.

Modification 3: The work under this CRADA is aimed at understanding several process effects 

on silicon wafers and/or solar cells. These include: (i) effects of wafering by diamond wire 

sawing on the surface damage and the strength of wafers, (ii) electronic characteristics of 

dielectric-Si interfaces, and (iii) characteristics of Si-Al interfaces formed during firing of silicon 

solar cells.

Summary of Research Results:

Please note the original PI on this project is no longer at NREL and neither is his predecesor. A 

stop work order was issued for this project in December 2013, so not all of the items were 

completed. Notes are made about some of the previously documented work.

1. CIGS Cell and Module Structure Process and Equipment Optimization, towards PV 

Manufacturing – Optimize manufacturing processes and equipment to close the efficiency 

gap between lab prototyping and commercial production of high efficiency CIGS cells. 

Assist in implementing productivity approaches towards developing factory systems for next 

generation PV fabrication.

PVMC staff members visited NREL and observed CIGS device processing. This included all 

layers from cleaning glass through top grid contacts. Personnel were trained to implement the 

NREL 3-stage process for depositing high-efficiency CIGS absorbers. NREL absorber 

samples were sent to PVMC for device finishing. Current-voltage measurements of these 

devices were compared to devices completed at NREL. NREL also provided SIMS depth 

profile data for comparison with CIGS absorbers fabricated at PVMC.

2. Accelerated Testing and Failure Analysis – Methodology Development for CIGS 

Reliability Enhancement – Characterize CIGS materials and process integration 

interactions to develop specific models around failure mechanisms, performance, and yield to 

provide direction for process and equipment improvements.

This task was not fully implemented.

3. Metrology Development – Develop metrology techniques for CIGS materials and PV 

modules.

Development was started on the use of optical ellipsometery for CIGS characterization. This 

report describes the preliminary analysis of a real sample made by the NREL CIGS group. 

The structure is CIGS/Mo/glass. The CIGS layer was deposited with in industry-like process: 

sputtering Cu+Ga/sputtering In/selenization. The average Ga/III ratio measured by XRF is 

0.31. The cross-sectional SEM image and the SIMS depth profile are shown in Figure 1. The 

experimental reflectance data and the fit are shown in figure 2. The fit returned the following 

parameters:
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

1. Total CIGS thickness of 1470 nm.

2. On top of Mo, there is a 57 nm thick interface layer that contains 23% Mo and 77% 

CIGS.

3. On top of layer-2, there is a porous CIGS layer 494 nm thick with 20% void and 80% 

CIGS. The Ga/III ratio in the CIGS in layers 2 and 3 are both 0.5.

4. On top of layer-3 is the dense CIGS layer. Its total thickness is 896 nm, with a bottom 

Ga/III ratio of 0.5 and a top ratio of 0.1.

5. On top of layer-4 is the surface roughness layer 24 nm thick.

Figure 1. The cross-sectional SEM image and the SIMS depth profile of the measured sample.

Figure 2. The experimental reflectance data and the model fit.
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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

That the difference between data and fit is similar to or may be even larger than the difference 

between two previously simulated curves corresponding to different Ga profiles. It seems singleshot optical metrology alone is not a reliable way to deduce the Ga profile. We shall try to 

highlight the potential for process control, meaning if we have a standard process and its 

standard optical signal, then certain deviations from it can be detected. More simulations will be 

done for this purpose.

Both p- and s- polarized reflectance were measured in a wide range of angle of incidence: 15 –

80 degree. Reflectance measurements become less accurate at larger AOIs, indicated by a c-Si 

sample. The curves in my report is p- polarized reflectance at AOI=15 degree. I also took the 

ellipsometry data of these samples. I found large discrepancy between the fit results based on SE 

and R data. Actually I cannot find a good fit to the SE data, possibly because it is too sensitive to 

the surface conditions.

The SEM and SIMS data of all of the four samples from NREL are in Figure 3. Figure 4 compares 

their p- reflectance at AOI=15. The significantly lower reflectance for C3462 and C3526 is due to 

the surface scattering, instead of anything in the bulk of the CIGS film. It is necessary to take this 

scattering into consideration for reflectometry analysis. This is one lesson learned from measuring 

NREL samples. The ellipsometry software we are using does not support this capability.

Figure 3. Plan view SEM (top images), cross-sectional SEM (center images), and SIMS depth 

profiles (bottom graphs) of CIGS absorbers made from different process noted in the rows above.
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Figure 4. The experimental reflectance data from the four samples in Figure 3.

4. Cost Modeling and Market Analysis – Create cost models of CIGS PV modules, broken 

down by material and process step, to assess future cost targets by category needed in order 

to reach the SunShot goals.

A presentation was given to PVMC by Alan Goodrich from NREL in March of 2013. It 

discussed a market summary and analysis in support of R&D strategies on crystalline silicon, 

CdTe, and CIGS. PVMC published their own cost model at IEEE PVSC in 2013. This task was 

not fully implemented.

Subject Inventions Listing:

None

ROI #:

None

Report Date:

30 April 2018

Responsible Technical Contact at Alliance/NREL:

Lorelle Mansfield (previously Kannan Ramanathan and Rommel Noufi)

Name and Email Address of POC at Company:

Pradeep Haldar, phaldar@albany.edu

DOE Program Office:

Office of Energy Efficiency and Renewable Energy Solar Energy Technologies Office

This document contains NO confidential, protectable, or proprietary information.