| azonenberg | go for it | 00:08 |
|---|---|---|
| didja | why do people heat silicon up to really hot temperatures like in this paper? (page 2 http://dl.dropbox.com/u/68719865/prl-strain-in-nanoscale-germanium-hut-clusters.pdf ) | 00:15 |
| didja | they say specifically: "The substrates were polished Si(001) wafers, cleaned by prolonged outgassing at 875 K followed by flashing to 1425 K." | 00:15 |
| didja | does this mean that they are making the silicon oxide disintegrate too? | 00:15 |
| azonenberg | didja: i think they're trying to burn off any contamination on the surface | 00:18 |
| azonenberg | and no, lol | 00:18 |
| azonenberg | 1400K = around 1100C | 00:18 |
| azonenberg | heating in atmosphere at that temperature will actually *grow* oxide | 00:19 |
| didja | so the germanium grown on top of it is definitely on SiO2? | 00:20 |
| didja | i don't know why people are so hazy about what they mean in papers | 00:20 |
| didja | just come out and say it damn it | 00:20 |
| azonenberg | I havent read the paper yet | 00:22 |
| azonenberg | kinda tired, been working all day | 00:22 |
| azonenberg | will go back and look probably tomorrow | 00:22 |
| didja | well this was done in UHV | 00:31 |
| didja | and another paper seems to suggest temperatures as low as 600-800 C are enough for thermal decomposition of 1 nm thick native oxide | 00:31 |
| azonenberg | Hmm | 00:31 |
| azonenberg | So you're heating oxide in vacuum | 00:31 |
| azonenberg | and tryingto break it apart? | 00:31 |
| azonenberg | or they are, at least | 00:31 |
| azonenberg | the only two reasons i've seen for heating silicon are growing oxide | 00:32 |
| azonenberg | and diffusion | 00:32 |
| didja | http://dl.dropbox.com/u/68719865/nanoscale-in-situ-investigation-of-ultrathin-silicon-oxide-thermal-decomposition.pdf | 00:32 |
| didja | the dealy-grove model breaks down under 20 nm of thermal oxide i think | 00:33 |
| azonenberg | didja: interesting | 00:33 |
| didja | deal-grove i meant | 00:33 |
| azonenberg | yeah, i know what you mean | 00:33 |
| didja | shoot don't trust me on that. i just read that somewhere and now i can't find remember where | 00:34 |
| azonenberg | 20nm thoguh? | 00:34 |
| azonenberg | thats a lot | 00:34 |
| azonenberg | 20A maybe | 00:34 |
| azonenberg | i cant say i'm surprised that it breaks down under extremes | 00:34 |
| azonenberg | and its meant for air, not vacuum | 00:34 |
| didja | http://www-inst.eecs.berkeley.edu/~ee143/fa10/lectures/Lec_07.pdf | 00:35 |
| didja | < 20nm | 00:35 |
| didja | page 19 | 00:35 |
| berndj | didja, as far as i understand it the wavelengths you're using for x-ray diffraction are such that the fact that you have an insulating layer etc is completely invisible | 00:36 |
| didja | say that again? | 00:36 |
| didja | the Si underneath (mechanical substrate) is visible and it's i think n-type doped | 00:37 |
| didja | the SiO2 though... does SiO2 even show up as anything in XRD? | 00:37 |
| didja | it's amorphous so i imagine it just adds a lot of background noise? | 00:37 |
| berndj | visible in that you can see how its atoms are arranged wrt each other, but not visible in the sense that you can't see that it's "below" whatever else you're looking at | 00:38 |
| didja | sure | 00:39 |
| didja | so if Si is visible in the xray spectra? is Ge visible in the XRD spectra? SiO2 is amorphous so by definition you sould not see any distinct peaks in its XRD spectra | 00:40 |
| didja | why do people do experiments on Si (111) substrates? | 00:56 |
| didja | i still haven't really gotten a good grasp of crystallography | 00:56 |
| didja | just last week i was pouring over communication systems stuff, now that the final is over, i can get back to stuff i like a bit more | 00:57 |
| didja | well, comm. systems was fun, but no lab = no fun | 00:57 |
| didja | azonenberg: how do you do research by the way? i'm looking forward to being a graduate student, but i'm scared too of the daunting task of being responsible for coming up with new ideas that have to work (publishable stuff) | 03:13 |
| azonenberg | didja: your advisor is likely to be a good resource there | 13:47 |
| azonenberg | he'll know the field well and have a good idea of where the holes are | 13:47 |
| --- Sat Mar 24 2012 | 00:00 | |
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