We are making GeMn QDs on Si(001). After finishing making QDs we deposit a 2 nm thick Si layer on top in order to protect the materials from oxidation. Of course, the capping layer will be oxidized afterwards. Do you have any idea about the thickness of the silicon oxide on top of the capping layer? I need the information for XMCD measurements.
The native silicon oxide layer is about a few nanometers for bulk silicon.
Good question. No answer but note that the oxidation will "of course" reduce your 2nm Si thick and this is usually a continuous process (it does NOT stop). So your storage condition is also very important (avoid water).
Some years ago, we measured "pure Silicon" samples with Elastic Recoil Detection. If the samples have been exposed to air, there is always some oxygen (and carbon) on the surface. Typically about 5 to 6e15 atoms/cm2. Assuming all this is SiO2 with bulk density, this corresponds to a layer thickness of roughly 1 nm.
Thank you all for your answers!
@Artur Braun:
We deposit Si from a Si source in MBE chamber at RT with the pressure of 2.10-9 Torr, which means the amount of O2 inside is insignificant. After finishing experiment, samples will be taken out and, of course, be exposed to air and then be oxidized.
From TEM measurements we usually get about 1.5nm SiO2 thickness for Si oxidised in dry air at room temperature; higher temperature and moisture will give values above 2nm and more.
A thin layer of oxide will form, while depleting the mass of the Si. Further mechanistic details regarding the self-limiting oxidation process, which results in a particular temperature and geometry governed oxide layer thickness are presented in a study attached here for your consideration
Article Two-dimensional modeling of the self-limiting oxidation in s...
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