Oerlikon is a Swiss company that makes thin-film solar production equipment.ÃÂ Oerlikon is the worldwide exclusive licensee of “micromorph” tandem cell technology, which it acquired in 2003 from the University of Neuchatel in Switzerland.ÃÂ
Micromorph tandemÃÂ cells have two different silicon materials – amorph and microcrystalline – in a top and a bottom cell.ÃÂ This setup increases efficiency because the amorphous top cell converts the visible light from the sun while the microcrystalline bottom cell absorbs sunlight in the infrared part of the spectrum.
The technology is covered by a family of patents, including European patent EP 0 871 979 (EP patent) and U.S. Patent No. 6,309,906ÃÂ (U.S. patent), and generally provides a process forÃÂ making thin-film solar cells usingÃÂ microcrystalline or nanocrystalline silicon.ÃÂ As discussed inÃÂ Oerlikon’s U.S. patent,ÃÂ this patent family addresses some of the problems of thin film solar cell production andÃÂ facilitates large scale production.ÃÂ
Last month Oerlikon sued German thin-film solar cell maker Sunfilm AG (Sunfilm) in the German District Court of Dusseldorf (pictured above), alleging infringement of the EP patent.*ÃÂ
One common method of laying microcrystalline silicon on a substrateàto make solar cells is called Chemical Vapor Deposition (CVD) and involves usingàone or more volatile gases, which react or decompose to deposit the desired material.àCVD often results in defects in the silicon layer, including weak photocurrent and negative “doping.”à(doping means intentionally adding impurities to a semiconductor to increase the number of free charge carriers; the level of doping needs to beàcontrolled to achieve efficient solar cells).àAccording to the U.S. patent, oxygen is one culprit that can cause flaws in the microcrystalline silicon layer.ààOerlikon’s patented technologyàovercomes these problems by purifying one of the gases before the silicon deposition step to reduce the oxygen content of the deposition gas.ÃÂ
One interesting point here is that Oerlikon, a production equipment manufacturer, has not sued a direct competitor in Sunfilm, but has instead sued a competitor’s customer (Sunfilm is a thin film solar cell manufacturer, not a production equipment maker)ÃÂ .
Therefore, this lawsuit has raised the question whether Oerlikon also plans to sue Sunfilm’s supplier, California production equipment makerÃÂ Applied Materials, Inc.ÃÂ (AMAT) (Sunfilm recently awarded AMAT a contract to supply a second line of manufacturing equipment).ÃÂ Although Oerlikon denies that it intends to sue AMAT for infringement, AMAT knows it may be in the line of fire and has taken a preemptive step in the court of public opinion.ÃÂ It has issued aÃÂ statement defending its manufacturing process and asserting that it does not infringe Oerlikon’s patent.
* Unfortunately, I can’t get a copy of the complaint filed by Oerlikon – a German patent attorney informed me that German court papers are only available upon written request and only if one can demonstrate a special interest in the case.ÃÂ I also can’t get an English translation of the European patent.ÃÂ Thus, I will limit my discussion to the U.S. patent (which is a sister application of theÃÂ EP patent and therefore contains a similar or identical description of the technology).