I need to form a SiO2 layer over a silicon wafer, I have a CVD setup and oxygen gas.
I don't know at what temperature and how long for deposition to take place?
Since you have only O2 gas, I suppose you want to convert Si to SiO2 by oxidation but not a deposition. What's your purpose to form SiO2?
Tuan Hoang yes, as you say I want make an oxide layer .
for solar cell, and graphene analysis
According to your purpose, an oxidation process using O2 is a good approach to get uniform SiO2. I suggest using 1000 oC and with a pump for better uniform. It is noted that O2 diffusion will be slow down when the thickness of SiO2 increases and therefore, the oxidation rate is decreased over time. I suggest using ellipsometry to confirm the thickness.
By the way, I'm curious why don't you buy SiO2/Si instead of making by yourself, if you want to analyze graphene. According to a previous report (ACS Nano 2013, 7, 11, 10344–10353), you need at least 90 nm to get a good characterization (other good thickness of SiO2 is 300 nm).
Tuan Hoang It is very expensive for me.
thank you so much for your help.
It depends on how thick of layer you are looking for. Exposure to ambient environment will form roughly a nm of oxide layer.
But, if you're looking to use it for solar cells, you will probably want to either grow it or purchase it. It may be worth reaching out to a company and explain you are a graduate student looking for SiO2/Si wafers. They may be willing to provide a sample or cut a discount. It doesn't hurt to try.
For growing it, there are a variety of methods and needing a dry procedure along with your specific equipment requirements will narrow them down quite a bit.
Anthony Trofe I agree with you, in the end I will buy it, I tried the wet way and got a layer but it's not good.
It seems you got SiO2. There is a few point defect I guess because of contamination, if you already clean substrate before oxidation then it might come from your CVD. In addition, I saw the difference at the edge, and I suppose you already use a pump so it might come from a temperature gradient.
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