Abnormal color on the surface of silicon rods
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Previously, the surface of the normal silicon rods produced by our factory was a shiny gray color. However, the silicon rods produced recently often exhibit abnormal colors, mostly grayish-black or black; sometimes they even take on a dark green color. Often, only part of the entire furnace is affected; in most cases, most of it is affected, while in fewer cases only a small area becomes darker. Dear sea friends, what is the reason for this?
Did nitrogen get trapped in during growth, resulting in the formation of nitrides?
Reply to 2# youyuan_2008: It shouldn’t be that reason; this phenomenon didn’t occur either when using nitrogen for displacement during previous shutdowns.
I’m afraid it’s due to an increase in the carbon content in the hydrogen or chlorosilane you have recovered
Personally, I think carbon must have been mixed in to form silicon carbide; it’s likely that there is carbon present in your feed gas, with methane being the most probable candidate
This post was last edited and replied to by hmc54 on 2011-3-8 at 18:51. Reply 1#: yuanrs – One could consider the issue from the perspective of hydrogen; if using hydrogen as a bypass gas, trying to replace it with electrolyzed hydrogen or recycled hydrogen might help improve the situation. Also, during shutdowns, sufficient burn-time is necessary, and the amount of hydrogen used as a bypass gas should not be too low, to ensure an appropriate flow rate of gas.
The carbon content can be measured!
I hadn’t encountered it before; now I’m learning more about it*
Reply 1# yuanrs: It would be best to send a picture for a look!