A non‐contact low‐cost sensor for improved repeatability in co‐evaporated CIGS

Repins, Ingrid; Fisher, Daniel C.; Batchelor, W.; Woods, L.M.; Beck, M.

doi:10.1002/pip.591

Cited by 12 publications

(11 citation statements)

References 26 publications

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“…It makes use of the fact that in the Cu‐rich stage of film growth, the infrared emissivity is higher. Thus at constant substrate heating, the substrate temperature becomes lower 10. This method, although reliable for stationary substrates, appears to be problematic for moving substrates due to the possibly varying distance between the thermocouple and the substrate.…”

Section: Process Controlmentioning

confidence: 99%

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Advanced diagnostic and control methods of processes and layers in CIGS solar cells and modules

Scheer

Pérez-Rodrı́guez

Metzger

2010

Progress in Photovoltaics

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Process monitoring and quality assessment for Cu(In,Ga)(Se,S) 2 (CIGS) absorber layers is discussed. One focus is on laser light scattering (LLS) as a tool for process diagnostics. This technique can give in situ and real-time information about CIGS film growth using sequential as well as evaporation processes. Raman spectroscopy is presented as a method to assess the fundamental structural properties of as-grown films. Experience shows that the specific structure of Raman lines can be interpreted in relation to device performance. Raman spectroscopy is particularly useful for material development and achieving at least average solar cell efficiencies. Time-resolved photoluminescence (TRPL) goes one step further and is generally related to the solar cell performance. It tracks carrier population decay after optical excitation and thus gives quantitative information about the most efficient recombination channels and material quality. It is apt to optimise the absorber of highly efficient devices. We will recommend how to use the three methods appropriately and will discuss requirements for industrial applications.

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Section: Process Controlmentioning

confidence: 99%

“…A remote method which makes use of the emissivity change during Cu‐poor to Cu‐rich composition transitions is photometry. It has been tested extensively for thermopile 10 and semiconductor‐based pyrometers 11. For a stationary substrate which may revolve due to rotation movement, this method appears very reliable 11.…”

Section: Process Controlmentioning

confidence: 99%

Advanced diagnostic and control methods of processes and layers in CIGS solar cells and modules

Scheer

Pérez-Rodrı́guez

Metzger

2010

Progress in Photovoltaics

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“…Traditional pyrometry 7 is not applicable to CIGS because of the complicated wavelength dependence of CIGS emissivity in the IR, 8 although some exploration of pyrometry for CIGS and other samples with strongly wavelength-dependent emissivity has been performed. This method, of course, is application of a contact thermocouple to the substrate, and is adequate for temperature measurement of stationary substrates of substantial thermal mass (e.g.…”

Section: Diagnostics For the Absorber Layermentioning

confidence: 99%

“…On the other hand, a 1/r 4 overall dependence of signal on sensor-to-sample distance occurs, as fluorescence intensity decreases with the square of the distance from the sample, and exciting x-ray intensity also attenuates with the square of the distance to the sample. 8,18 Wide band detection offers some advantages in signal strength, sensor cost, and ability to operate at elevated temperatures. However, XRF is well-suited for use with moving substrates when placed just after the deposition zone.…”

Section: Diagnostics For the Absorber Layermentioning

confidence: 99%

In Situ Sensors for CIGS Deposition and Manufacture

et al. 2005

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In situ sensors are an important tool for process control, optimization, and documentation, both in the laboratory and industrial environments. Their further application to deposition of CuIn x Ga 1-x Se 2 (CIGS) for photovoltaics is particularly important, as record device efficiencies produced in the laboratory have yet to be replicated in manufacturing. This paper provides an overview of the current state of the art of in situ diagnostics for devices based on coevaporated CIGS.

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“…Second, in the bell jar, software has been developed to automatically identify the Cu-rich emissivity change via thermopile and to insure that maximum and final Cu-ratios are as consistent and operator-independent as possible. This method of film monitoring was described briefly in the previous annual report, and in a recently-submitted journal article 23 attached to this report. Third, also in the bell jar, a designed experiment examining maximum Cu ratio and atoms deposited in the third stage, 24 is being performed.…”

Section: X-axis Uncertainty Inmentioning

confidence: 99%

Tolerance of Three-Stage CIGS Deposition to Variations Imposed by Roll-to-Roll Processing: Phase II Annual Report, May 2003--May 2004

Beck¹,

Repins²

2004

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Co-evaporation of CuIn x Ga 1-x Se 2 (CIGS) via two-stage and three-stage processes has been used in a variety of laboratories throughout the world to produce small-area devices with efficiencies greater than 15%. Thus, these deposition methods have come to be viewed as laboratory standards for the formation of CIGS absorbers used in respective photovoltaic devices. Although quite successful and relative easy to implement on a small R&D scale, scale-up to a commercially viable level proves to be rather challenging, as a number of conditions are encountered during continuous manufacturing that differ from the laboratory process. Such differences include both those imposed by continuous processing of moving substrates, and those implemented to decrease costs and increase throughput. It is therefore beneficial to understand the tolerance of the established laboratory processes to variations in deposition procedures. Research under this program consists of four basic parts to examine the tolerance of the established laboratory process to variations in deposition procedures: 1. Setting up the National Renewable Energy Laboratory (NREL)-developed three-stage CIGS laboratory process in a bell jar. (Phase I) 2. Characterizing the GSE roll-to-roll production chambers and device finishing steps in terms of the variables important to the laboratory processes. (Phase II) 3. Using the bell jar system to step incrementally from the NREL process to the conditions experienced by a sample during manufacturing, and characterizing the resulting films and devices. (Phase II and III) 4. Applying the process sensitivity information gained from the bell jar system to the production systems to realize improved device performance, yield, and process robustness. (Phase II and III) Work during Phase II progressed in three major areas: production system characterization, quantification of process sensitivities in the bell jar, and application of results to the production roll-coaters. To form a complete picture of conditions in the production systems, metals flux profiles as a function of Se pressure were documented, Se impingement rates were derived from sensor data, and thermocouple data was used to estimated temperature profiles. In the bell jar, the impact of the following process variations on device performance were quantified: CIGS cool-down rate, cool-down Se flux, venting temperature, shortened time between venting and CdS, maximum Cu ratio, and final Cu ratio. Related to production systems, the following topics were investigated: process robustness and device performance as a function of maximum and final Cu ratio, real-time sensing of maximum Cu ratio, effect of processing delays between CIGS and CdS, transparent conducting oxide stability with exposure to damp heat, and improved junction formation via thioacetamide treatment. Phase III tasks will build on this year's results: In the bell jar, several process sensitivity investigations will be concluded, and some new ones begun. These investigations will include use of less expen...

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A non‐contact low‐cost sensor for improved repeatability in co‐evaporated CIGS

Cited by 12 publications

References 26 publications

Advanced diagnostic and control methods of processes and layers in CIGS solar cells and modules

Advanced diagnostic and control methods of processes and layers in CIGS solar cells and modules

In Situ Sensors for CIGS Deposition and Manufacture

Tolerance of Three-Stage CIGS Deposition to Variations Imposed by Roll-to-Roll Processing: Phase II Annual Report, May 2003--May 2004

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