CIG

It is common to hear people that are skeptical about CIGS technology ask questions like:

• "Aren't indium and indium tin oxide (ITO) thin film deposition processes wasteful and inefficient?"
• “Aren’t we going to run out of indium soon? Doesn't the world use more than we produce!”

What are the truths?

Here they are:

WASTEFUL: A well-run process is NOT wasteful. Why? Recycling!

At first glance, a process like indium planar target sputtering seems ridiculous – generally only 30% of the indium actually makes it onto the substrate it is destined for (and that’s in a well-tuned process). As it turns out, the material that doesn’t land on the substrate is too valuable to just scrap. This translates into recycling, a lot of recycling…

According to presentations given at Minor Metals 2012: “indium production will total 1,500-1,700 tonnes in 2012, with virgin supply accounting for around a third of total output”.  It’s incredible that recycling accounts for such a large percentage of the indium used in the world today.

INDIUM AVAILABILITY AND SUPPLY: Another important conclusion made at the conference was (as reported in Metal Bulletin):

“proven indium reserves from existing mines at 50,000 tonnes, a volume that will be sufficient to satisfy demand for the next 75 years”.

While it’s not news at Indium Corporation, it is definitely assuring news for those looking to get involved with CIGS technology.

~Jim

Q1) What the heck are we looking at in this picture?

A1) It’s a CuGa (copper gallium) target being sputtered at Angstrom Sciences, Inc. test lab. Since CuGa rotary sputtering targets are becoming more popular in the CIGS deposition industry, we wanted to see how they work with AS cathodes. The result: a winning combination!

Angstrom Sciences Lab








Q2) Why haven’t Cu-Ga rotary targets been more popular for production of CIGS solar cells (a thin film technology)?

A2) The big problem has historically been segregation of the copper and gallium in traditionally cast targets. This was a hot topic for those who stopped by the booth at the Society of Vacuum Coaters TechCon and checked out our full size CuGa display target. It is only natural to question if a display piece actually works well in a production sputtering process. In order to make this product work, we had to manufacture it using our proprietary hybrid consolidation technique.

Without giving away all the juicy details, I can tell you that it was a learning experience and that there were some setup issues that led to improved applied power settings. Our customers have been pleased with the results of our CuGa targets, although the fine tuning is proprietary to them and we cannot share their learnings. Now we have a much better understanding of the maximum power we can use for this type of target. That's why it was so important to work with an equipment supplier.

One thing that is obvious from looking at the spent target is the lack of an erosion groove from magnet dwell - a nice feature of the magnetron that was used. The spent target is on display in my boss’ office. It serves as a reminder of the time we spent with the Angstrom Science guys sputtering the target, gathering data, and learning from the team.

This year’s Society of Vacuum Coaters Technical Conference was certainly as focused on vacuum deposition as it has been over the years, but we were delighted by the new emphasis placed on solar cell fabrication. As I mentioned before , one of our key topics was thermal evaporation material - although we also presented on the topics of nano-bonding sputtering targets and the availability of indium and gallium. Along with these topics, the audience was treated to themes of cell fabrication, increasing solar cell efficiency, and roll-to-roll processing.

At the show, we had a chance to discuss new ideas with many of our existing and potential customers. Improved throughput and eliminating alloy segregation were hot topics at the Indium booth. Many customers wanted to learn more about CIGS materials like indium forms for evaporation, or full-size Cu-Ga, CIG, & In rotary targets for magnetron sputtering.

2011 raised the bar for the Society of Vacuum Coaters Tech Convention, I can’t wait for the 2012 event to top it!

“Hi, this is Jim Hisert. I just read an interesting article and I wanted to share it with you. In the 2010, October edition of PV magazine, the cover story on page 70 was pretty interesting, so here it is…

It’s called Rotatable Rotatables, and it discusses rotatable targets. The really nice thing about the article is: it goes through the physics of sputtering and gives you the background of what magnetron sputtering is all about. Then it talks about different kinds of targets. It talks about the difference between rotatable targets and planar targets, the different compositions of targets. And then it also goes into talking about the supply of indium and gallium, different target materials, as well as the difference between thermal vapor deposition and sputtering – the advantages and the disadvantages. It even wraps up with refining and recycling of the material and talks about the process overall.

So I advise that you check this out. It’s in the latest (October) edition of PV magazine. Thank you.”  ~Jim

Keywords: Solar, sputtering targets, copper indium gallium, CIG, indium, thin film technology

Are you scaling up to a rotary sputtering system from your current planar target line?

That’s a big jump! New equipment, new materials, new process challenges. I hope we can help you make this an easier transition. One of the issues you may be concerned with is the segregation of gallium in the new targets. Fortunately we produce our rotary targets using a hybrid consolidation process. Although I cannot share the processing details of this method, I can say that it sets Indium Corporation’s targets apart from what few competitors are out there right now. We offer Copper Indium Gallium sputtering targets as well as Copper Gallium sputtering targets. If you’re interested and would like to learn more just follow this email link: solar@indium.com

The word ‘cadmium’ (Cd) has a negative connotation to anyone who deals with solder alloys or health and safety regulations. If you are using toxic cadmium sulfide as a buffer layer for CIGS PV cells, I urge you to explore indium sulfide (In₂S₃) as a replacement. Alternative energy should focus on being environmentally conscious, starting with the bill of materials for the solar cell.

最近Indium 公司第一次成功參展了SNEC 第四屆(2010)國際太陽能光伏大會（上海）。 同事回來分享他的大概感受：

1．  展會的規模比Nepcon還要大好幾倍！(Nepcon是中國SMT行業的盛會)

2．  整個中國太陽能生産組裝產業鏈各個環節都相對成熟並具有規模。

3．  太陽能產業中的核心技術（光電轉換率什麽的）做得強的，目前還不在中國。

Indium公司在展會中，主要推出了三款成熟的產品：

1．  前端的太陽能板子製造：CIGS Target 铜铟硒化镓濺射靶， 和Metallization Paste含銀導電漿料。這兩款產品都主要是針對薄膜太陽能光伏技術的板子的。(Thin-Film Solar Panel)  

2．  后端的太陽能板子組裝：Tabbing Ribbon 鍍錫銅帶。這是太陽能板組裝所用到的材料。

Cheers!  



Pic: Indium Corporation

Wandering through the references to indium metal on the internet, I sometimes see it referred to as, "that 'rare' metal."  But is it really so rare?  I recently talked to my colleague, Claire Miko, Director, Metals and Chemicals for Indium Corporation and asked if the reports of the rarity of the metal (like the death of Mark Twain) were greatly exaggerated.

Question:  The element indium is widely used today in many electronic (glass coating, low temperature solder, hermetic sealing and thermal interface material) and solar applications (CIG solar panels), but very little is known about it.  Can you tell us where indium metal comes from?

Claire:  Indium is a by-product of several base metals such as zinc, lead, copper, tin and other poly metallic ores. It is very abundant on the crust of the earth (much more than silver for example and the annual silver production is at least 40 times bigger than the annual indium production). Geographically indium is abundant in South America, Canada, Australia, China and the CIS, i.e. the reserves are widely spread.

 
Question:     Does indium have to be refined after it is mined?

Claire:    Indium is present in the base metal ores at ppm levels. It first needs to be separated from the base ore and concentrated. This is done at the base metal smelter (for example during the refining of zinc, lead, copper, tin etc). It is then further refined and purified at indium refineries.

Question:  Indium Tin Oxide (ITO) is the one of largest indium-containing products today.  How much of the indium mined goes to making ITO?

Claire:   About 50% of the indium refined is used for making ITO. A larger percentage is needed to start the ITO target productions but the sputtering process used (when putting the ITO layer onto the glass) is inefficient and generates a large quantity of indium which is reclaimed and is then recycled and put back into circulation.

Question:     Is there enough indium available to meet the current and future needs of the marketplace?

Claire:   The indium production has always expanded to meet growing demand. Indium production grew from 70MT (metric tonnes/year to over 500MT/year over the last 20 years. At the moment only one-third of the indium mined yearly is being refined in indium metal, another third accumulates in residues that are more expensive to treat but they remain available for future processing, and the last third is currently lost because it does not reach a base metal smelter which has the equipment to separate it from the base metal ore. Investments at these smelters would enable the extraction and refining of these quantities if the need arose.

Question:    Are there recycling programs in place to recover unused ITO from the targets used to deposit it onto the glass surfaces where it is used?  What is the rate of recovery?

Claire:   There is ample capacity to treat spent ITO targets (as per point 3) and the recovery process is now mature and very efficient. The cycle time of this process has also now become very short enabling a very quick return of the refined indium for new consumption.

Question:    Are there any viable alternatives to ITO?

Claire:   A far as we know ITO remains the best material for LCD and other flat panel displays applications. It offers the best performances in terms of optical transparency, electrical resistivity, uniformity of both transparency and resistivity, chemical and mechanical stability, resistance to corrosion, and, finally, uniformity of etching.

The cost of the ITO on 42” TV represents less than $2 and less than 1% of the display cost. It is a small cost to pay to ensure that the quality of the display is maintained. Alternative materials have shown significant process problems with resistivity, uniformity and chemical and mechanical stability.

In the surface mount technology (SMT) electronics and semiconductor packaging industries, Indium Corporation has a reputation for offering custom solutions.  In the world of solar cell manufacturing, I hope that same status is obvious.  I feel custom solutions are even MORE important in emerging technology fields like CIGS cell manufacturing.  Being the leading global supplier of indium (the metal), and a supplier of unique solder alloy shape/size/tolerance forms, we are well equipped to offer you evaporation sources that are tailored to your application.  Sure, we can supply round shot, teardrop shot, wire, ingot, preforms, and various other bulk forms of solder to keep your evaporation chamber filled.  Did you know we can also make custom solder castings to fit your particular crucible?  The process is easy, let us know if you are interested!

(Just click here to get started)

The SNEC 4th International Photovoltaic Power Generation Conference & Exhibit in Shanghai is known as one of the BIG solar shows of the year. Indium Corporation’s Bill Jackson (Director of Solar Products) commented that the 2010 SNEC was: "A busy, well attended show exuding with confidence about the beginning of a worldwide economic recovery and good solar-related growth for the foreseeable future".  That’s good to hear! Luckily, we had a strong team there to handle technical inquiries. Attendees from Indium Corporation included:

• Bill Jackson
• Thomas Tong
• William Aw
• Tommy Fan
• Michael Qiu
• David Hu

Even Indium Corporation President Greg Evans stopped by to visit the booth, to network, and to take the pulse of the industry.

This year, the SNEC was especially important for us. We had a chance to show off some of our new technology and sputtering target capability. The visitor interest seemed to mirror this thought with “…high interest in rotary CIG (Copper Indium Gallium) and Cu-Ga targets, also high interest in target bonding with NanoFoil®".

I also wanted to take a second to thank the people behind the scenes that help to make shows like this possible. Special thanks to Bill Wilson for helping to make sure our display targets looked their best, Gene Loparco and his team for dealing with the logistics of transporting our materials to/from the show, and Anita Brown for helping out with the details of coordinating the show.  These Indium Corporation employees help us all shine at solar trade shows!

~Jim

This blog has been in existence for a little over two years now, and we would like to thank our readers for the feedback and inquiries you have provided. I welcome your comments on what you would like from us. Leave a comment below, or email me at jhisert@indium.com.

And now a look back on past topics of interest:
 

Grid Ink, Silver Ink, Conductive Ink

Bismuth/Tin Tabbing Ribbon, A Low Temperature Pb-Free Alternative

Plated Metallization for C-Si Solar Cells

Increase Packing Density for Evaporation Crucibles

Photon’s 5th PV Tech Show 2010 USA

IPC Solar Standards Update

Solder Shelf Life as Explained by Eric Bastow

Tips to Speed Your Solder and Flux Selection

What's Happening in the Technical Service Department 

A Day in the Life of a Tech Guy

A Clean Laboratory

CIGS for Beginners

3rd Renewable Energy Expo 2009 in New Delhi, India

Solar Products and Representatives

Kleenex®, Google™, FedX®, CIGs?

Indium Solar Products Reunited

Trade Show Visitors Love the Ground Floor

Solar Product Data Sheets

Intersolar 2009 – What Barrier to CIGS Technology?

Concentrator Photovoltaic Systems - Will they reach 50% Efficiency?

Standards for Solar Panel Manufacturing

Solar Panel Certification: “Barrier and Benefit” Reviewed by Eric Bastow

Low Temperature Metallization Paste

What Will Your Interest Be At InterSolar? Meet the Bloggers And Let Us Know.

Share Your Solar Images

SAC vs. Sn/Ag for Solar Soldering

Solder Thickness for PV Interconnect

What is Bus Ribbon?

Standard PV Interconnect Ribbon Sizes

No-Clean Flux

Photovoltaics in EMS Sector

PV Interconnect Products

Eric Bastow - East Coast Technical Support

Mario Scalzo - West Coast Technical Support

Au/Sn Sputtering Targets

SMT Goes Solar

A Trip Down Memory Lane 

More Information About Metallization Paste

A year in the Life of a Solar Blog

CIG Target

23rd European Photovoltaic Solar Energy Conference and Exhibition

TCO choices for CIGS manufacturing 

CIGS Absorber Layer Electroplating

No Slump Metallization Paste

Meet the Bloggers

CIGS - Can sputtering make a breakthrough?

Fluxes for Soldering Tabbing Ribbon

Computer Brain vs. Solar Photovoltaic

Beam it down from space

Selection of the Optimum Lead-Free Solder for Solar Tabbing Ribbon

Record Makes Thin-Film Solar Cell Competitive with Silicon Efficiency

Why Thin-Film Solar Cells are Here to Stay

Hot Rooftops to Flashy Digital Cameras

Synchronize Your Solar Cell

Solar Conversion Efficiencies  

Government Support is the Key

It's Just a Beginning ...

In an evaporative deposition process, source material is evaporated and then condensed onto a substrate which is being coated. One of the common uses that our solar team encounters is the deposition of indium (provided as shot) for CIG thin film technology.

It’s an easy concept: if you can fit more indium shot in a given crucible, the evaporation process can run for a longer period of time before material needs to be added. The traditional form of solder shot is a teardrop shape, which is easy to produce as a bulk form of solder. 

A newer version of shot is now available without the tail, we call this ‘round’ or ‘tailless’ shot. This material is similar to solder spheres, but not as precisely spherical. Compared to traditional shot, round shot offers a packing density increase of 15% - 20%. This means you can fit more source material in a given crucible, which can keep your evaporation process running longer, more efficiently, and more profitably.

Living in NY (or anywhere on the East Coast of the United States) and working with the solar industry usually means traveling to California. We don’t have as much sun, and we certainly don’t have as many solar customers, conferences, or venues to learn about solar technology.  Luckily, the College of Nanoscale Science and Engineering, SUNY at Albany (NY) is hosting a 2 day photovoltaic technology course April 20th and 21^st. Ernest Levine is teaching this course, you may know him from his IC Fab training that he provides a few times a year. I haven’t been to his solar training yet, but I know that he covers IC fab in a way that everyone can understand – plus he has the background to answer those tough questions that veterans throw at him. (You know, that one guy in the back that is just dying to stump the professor…)

According to Ernest: “This PhotoVoltaic Technology course covers this subject starting at the atomic level and building up to an atomic understanding of the inner workings of a photovoltaic cell.  Using a comprehensive in part animated slide presentation we will see how the charged particles move as well as cover details of the governing equation and how it came about and important controlling factors in efficiency and manufacturing of both thin films and crystalline Si. This includes amorphous Si, CdTe and CIGS as well as GaAs and concentrated and tandem cells. All you need to bring to class is a desire to learn and I will teach you.”

For more detailed information send him an email at elevine@uamail.albany.edu  or call him at (518) 437-8623.

Environmental initiatives coupled with the recent run-up when oil achieved $150 per barrell has put alternative energy back on the table. Solar energy was readily considered given its very "clean" and available nature. However, how can the average person, in their day to day life, take advantage of solar energy. Visions of roofs covered with (expensive and perhaps unattractive) solar panels and apparatus come to mind.
Well, an article in Photonics Media called "Painting the roof with solar ink" by Anne Fischer puts an interesting twist on capturing the suns rays for the sake of generating electricity. A company in the San Francisco Bay area, Innovalight, manufactures a solar ink comprised of silicon nanoparticles that can be suspended in a liquid. The "ink" can then be applied to flexible or rigid surfaces by means of "spray painting". Therefore, rendering virtually any surface that is exposed to the sun, a solar collector. Efficiency is said to be on the order of 18% currently. A company in China, JA Solar, has plans to commercialize this technology.
One of the founders of Innovalight, Brian Korgel, is trying to apply this approach to CIGS. Work done at the University of Texas has achieved 1% efficiency. The goal is 10% before going commercial and is anticpated to take 3 to 5 years

For a interesting and very technical introduction to CIGS (copper indium gallium selenium) technology, check out the 3^rd quarter 2009 edition of Photovoltaics International Magazine – page 112.  This article by ZSW is a good primer to get you up to speed with this thin-film technology.  (This blows the Wikipedia "CIGS solar" description out of the water!)

The article is a good read for those of you looking into CIGS technology because it goes well beyond the overview of what CIGS is with discussion of chemical and structural analysis of thin-film cells. 

I don't know about you, but I 'FedX' packages, I 'Google' terms I want to know more about, and I blow my nose with 'Kleenex'.  Those terms have become more than a standard, they have actually become an action in themselves.  Maybe one day the major classification of solar technologies will be "Crystalline cells" and "CIGS cells".  I bring this up only because one technology will surely find its way to the top in the race to be the most popular thin film technology.  Will we 'CIGS' a rooftop or 'CIGS' a solar farm?  Interesting…

This year at InterSolar I learned how misleading old (mis)information can be.  In a business as rapidly developing as the solar industry, you just can't cling to information from 2 or 3 years ago. 

Of course there was a good deal of discussion about which thin film technology would prevail in the future.  The argument against CIGS is usually based on the faults of CIG deposition, but this is an argument that is no longer valid.  High quality CIG targets are currently available and are being used by some of the top solar fabs.

It's good to know where we came from, but the solar industry is evolving way too fast for old information to be used in decision making.  As a way to help, let me know if you see any out-dated information if you are looking through old Solar Materials blog posts.  I will make sure those posts have the correct information showing the current status of the industry.

Thin Film PV Cell

最近小忙，只能凑凑杂文，不好意思。

1． 先请教大家一个问题，在太阳能光伏薄膜技术(PV Thin Film Technology)中, 哪种技术在中国领先？爲什麽呢？ 太阳能光伏薄膜技术，主要有这几种：

• Amorphous Silicon (a-Si): 非晶硅
• CIGS: 铜铟镓硒(Copper Indium Gallium Selenium)
• CdTe: 碲化镉   

2. 关于公司裏的开会。 前天中午看牙医，他又准备给我嘴巴里面打麻醉针了。"怎么这次又打？我还以为这次的小治疗不需要了。怎么每次下午我要开会发言，都会遇上你的麻醉针？叫我等会怎么说话呀？"牙医问"会议很重要吗？"我郑重其事的回答"当然！无论和谁开会，每一个会议都是重要的。因为除了自己能给会议带来value之外，也是展现自己的机会，别人也会在心中评价你的…"牙医笑道"Such a corporate girl! Please be quiet for now."然后他毫不手軟一针下来，我这个talking-box (话匣子)也慢慢地少话了…Anyway, 在公司里面，对于每一个会议都认真对待，做好准备，應該沒錯的。下次我看牙医前要问清楚是否要打麻醉针了，不然很有可能会一边说话一边不自觉地流口水的。

3.  无卤化 (Halogen-Free): 明天开始会去美国西部休假10天。我知道自己会被那里的更纯净的自然景色给shock的，也更加会想起祖国（或是第三世界国家）在电子垃圾废墟中的人们(e-waste)…还是老话，今天，你无卤化了吗？