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Topic: Germanium absorption cross section data in visible and IR?  (Read 6151 times)

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Offline red2erni

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Hi guys and gals,

Does anyone have data or a reference to definitive absorption cross section for Ge in the visible and IR. I'm interested if there is a change in these valuse vis energy for crystalline vs amorphous phases. If you have any such useful data (in any units) for GeSi (or SiGe ! ) alloy, crystalline or amorphous you would also get my top prise (a working solar cell). Phase diagrams for SiGe with transport properties are also useful.

Thanks,

red

red2erni@yahoo.com

Offline Arkcon

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Re: Germanium absorption cross section data in visible and IR?
« Reply #1 on: March 15, 2008, 03:11:45 PM »
The graphic below shows the transmission profile of an optics-grade germanium window.  I got it from the Edmund Scientific optics website: http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2685
It's worth having their print catalog on hand, even if you can find a cheaper supplier for your optical needs, because they have good info printed.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline red2erni

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Re: Germanium absorption cross section data in visible and IR?
« Reply #2 on: March 16, 2008, 02:33:29 AM »
Good catch in the Edmund Scientific Catalog! I know Ge can be used at 1.5u as a detector in the "C" band, and of course the farther IR transmission is good data. I'll go see if there was thickness data from which I can calculate the extinction coefficient and get a photon capture cross section. - But not quite up to a solar cell reward.

So, of course, I'm still looking for data in the visible. To build a solar cell containing Ge with a silicon or micro-crystalline silicon layer, it will be important to have the detailed data for the threshold region around the band gap. Data for the crystalline germanium band gap is readily available, but not for amorphous germanium. it is very likely that, like amorphous silicon, it will have a higher band gap than the crystalline material. it would also be quite important if there were data or reports for micro-crystalline germanium, since it wouldn't have grain boundaries and would no doubt also have a band gap that lies between the crystalline material and the amorphous material, all of which is quite easy to see would be important for thin film solar cells.

red

red2erni@yahoo.com

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