Carbonization increases pnc-Si stability
Dave gave me some carbonized samples several weeks ago to test stability/discoloration. I measured the contact angles right after I got the samples (posted here) and then started the discoloration. These are SC141 chips. Controls were untreated (1st column) and RTP’ed only (2nd column) chips. Two carbonization conditions were tested – 5 minutes of 1 L/min acetylene @ 700C (3rd column) and 750C (4th column). I had duplicates of each sample. Discoloration was performed in DMEM + 10% FBS + high NaHCO3 in the incubator:
The films deposited in the AJA are much more reflective than the older material, so it’s harder to get good pictures and to see subtle changes in color. Sorry about that. The carbonization procedure certainly delays discoloration/increases stability. Untreated samples discolored after 1 day and RTP’ed samples were completely discolored after 1 week. A couple of days later, the low temperature, 700C, carbonized samples discolored. After 3 weeks (as of May 4), the high temperature, 750C, carbonized samples are still not discolored. This is interesting because it correlates with the carbon thickness, as posted here. At higher temperatures, more carbon is deposited on the sample, and this seems to protect the underlying Si films from chemical attack.
