Chalcogenide-based materials and methods of making such materials under vacuum using post-chalcogenization techniques

a technology of chalcogenide-based materials and vacuum evaporation, which is applied in the direction of vacuum evaporation coating, solid-state diffusion coating, coating, etc., can solve the problems of difficult industrial application of conventional evaporation methods, inflexible, and rigidity of chalcogenide-based absorbers, etc., and achieves high quality.

Inactive Publication Date: 2011-11-24
DOW GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]The present invention provides strategies for making high quality, chalcogenide-based, photoabsorbing compositions from sputtered precursor film(s). The precursors are converted, into the chalcogenide photoabsorbing material, via a chalcogenizing treatment (also referred to as “post-chalcogenization,” including, e.g., “post-selenization” when Se is used and / or “post-sulfurization” when S is used) using techniques that allow the post-chalcogenizing treatment to occur under atypically and surprisingly low pressure conditions without significant indium loss. Consequently, the strategies of the invention are readily incorporated into batch processes or continuous processes such as roll-to-roll process occurring under vacuum. The present invention is useful at lab, pilot plant, and industrial scales.

Problems solved by technology

Crystalline silicon-based absorbers tend to be rigid, not flexible.
Making photoabsorbing chalcogenide compositions with industrially scalable processes is quite challenging.
Unfortunately, these conventional evaporation approaches are not easily scalable for industrial applications.
Using so much chalcogen-containing gas tends to cause equipment degradation and chalcogen (e.g. Se) buildup, target poisoning, instabilities in process control (resulting in composition and rate hysteresis), the loss of In from the deposited film due to volatile indium selenide compounds, lowered overall deposition rates, and the damage of targets due to electrical arcing.
Yet, serious challenges remain.
As one challenge, many known approaches tend to practice post-chalcogenization within relatively high pressure regimes, such as on the order of a few ton to atmospheric pressure.
Even in these higher pressure regimes, retention of In and Se during post-chalcogenization is a problem widely recognized in the industry.
It has been challenging to carry out the post-chalcogenizing treatment without undue loss of one or both of these materials.
The formation of volatile species is consistent with the observation that retention problems tend to become more severe at lower pressures.
Frustratingly, the post-chalcogenization techniques practiced with reasonable success at higher pressures often are not directly translatable to use at lower pressures.

Method used

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  • Chalcogenide-based materials and methods of making such materials under vacuum using post-chalcogenization techniques

Examples

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example 1

Fabrication of CIGS Solar Cell in a Roll-to-Roll Tool

[0069]Substrate preparation:[0070]A roll of 430 series stainless steel is loaded into a continuous roll-to-roll vacuum sputtering system. This active side of the web is first cleaned with ion etching and then is coated by magnetron sputtering with a Nb barrier layer, a dual layer of Mo for a back contact and a NaF layer to act as a sodium source. The back side of the web is coated with Cr as an adhesion layer and Mo to act as a sacrificial layer during the selenization process.[0071]Target arrangement[0072]The web is then translated into a Cu:In:Ga precursor sputtering chamber. Seven pulsed DC magnetrons are arranged in four zones. Each zone has individual gas control. The web is transported sequentially through the four zones. Each of the first, third, and fourth zones has 2 magnetrons. The second zone has a single magnetron. In this example, all magnetrons are adjusted to sputter parallel to the web. The web moves from magnetron...

example 2

Fabrication of Tetragonal CIGS in the Presence of H2S Gas (H2S) on a Cluster Tool at 6.6e-3 mBar and 350 C

[0081]Substrate preparation:[0082]A stainless steel coupon is first cleaned by sonication in solvent baths and dried with dry N2 gas and loaded into a multi-chamber vacuum deposition system. The face of the substrate is further cleaned using 300W RF plasma etching in Argon. The substrate is then transferred under vacuum to a second chamber where a niobium adhesion layer and molybdenum back contact layer are deposited by sputtering. The sample is removed from vacuum.[0083]Targets[0084]The substrate is later introduced into a precursor sputtering chamber comprising a single, commercially available Cu:In:Ga alloy target tilted off-axis with respect to the substrate to give a more uniform coating thickness. The target is 45:42:13 Cu:In:Ga. The sample is rotated during deposition.[0085]Deposition conditions The CIG precursor film is sputtered at 75 Watts, in ˜4e-3 mBar in Argon at am...

example 3

Formation of CIGS in H2Se at 10 mT, 25× cap, 350 C

[0092]Substrate preparation[0093]The substrate is prepared as in Example 2.[0094]Target arrangement.[0095]Targets are used according to Example 2.[0096]Deposition conditions[0097]Deposition of a CIG precursor on the substrate is carried out as in Example 2.[0098]Description of cap formation on precursor[0099]A Se cap is formed on the CIG precursor as in Example 2.[0100]Anneal conditions.[0101]After application of the selenium cap, the substrate bearing the CIG-Se stack is removed from vacuum and transferred to a selenization chamber. In this chamber, the substrate is suspended face down and heated from the back-side with a radiative graphite element. The system has water-cooled walls (2Se gas prior to heating. The substrate ramped up to >350° C. at 20° C. / min by setting the power supply for the graphite heater at a previously determined power duty cycle value. The temperature of the substrate is maintained at >300° C. for 20 minutes ...

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Abstract

The present invention provides strategies for making high quality CIGS photoabsorbing compositions from sputtered precursor film(s). The precursors are converted into CIGS photoabsorbing material via a chalcogenizing treatment (also referred to as “post-chalcogenization,” including, e.g., “post-selenization” when Se is used and/or “post-sulfurization” when S is used) using techniques that allow the post-chalcogenizing treatment to occur under atypically low pressure conditions. Consequently, the strategies of the invention are readily incorporated into batch processes or continuous processes such as roll-to-roll process occurring under vacuum. The present invention is useful at lab, pilot plant, and industrial scales.

Description

PRIORITY[0001]The present nonprovisional patent application claims priority under 35 U.S.C. §119(e) from United States Provisional patent application having Ser. No. 61 / 346,515, filed on May 20, 2010, by Nichols et al. and titled CHALCOGENIDE-BASED MATERIALS AND METHODS OF MAKING SUCH MATERIALS UNDER VACUUM USING POST-CHALCOGENIZATION TECHNIQUES, wherein the entirety of said provisional patent application is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to methods for making chalcogenide-based photoabsorbing materials as well as to photovoltaic devices that incorporate these materials. More specifically, the present invention relates to methods for making chalcogenide-based photoabsorbing materials, desirably in the form of thin films as well as to photovoltaic devices that incorporate these materials, in which a precursor film is prepared and then converted to the desired photoabsorbing composition via a chalcogenization treatment.BACKGR...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C23C8/62
CPCC23C14/0623C23C14/24C23C14/5866C23C14/5806C23C14/34
Inventor NICHOLS, BETH M.NILSSON, ROBERT T.LANGLOIS, MARC G.XIONG, RENTIAN
Owner DOW GLOBAL TECH LLC
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