Effects of post oxidation of SiO2/Si interfaces in ultrahigh vacuum below 450 °C
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Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2022-08
Major/Subject
Mcode
Degree programme
Language
en
Pages
8
Series
Vacuum, Volume 202
Abstract
Growing SiO2 layer by wet-chemical oxidation of Si surfaces before growth of another insulating film(s) is a used method to passivate Si interfaces in applications (e.g., solar cell, photodiode) at low temperatures (LT) below 450 oC. We report on potential of LT ultrahigh-vacuum (UHV) treatments combined with the wet-chemical oxidation, by investigating effects of LT-UHV oxidation after the wet-chemical growth of SiO2 and before growing Al2O3 film on top of SiO2/Si. This method modifies the SiO2/Si and is found to (i) decrease defect- level density, (ii) increase negative fixed charge density, and (iii) increase carrier lifetime for Al2O3/SiO2/p-Si, as compared to state-of-the-art SiO2/p-Si reference interfaces without LT-UHV. X-ray photoelectron spectroscopy shows that the LT-UHV treatment decreases amount of Si+3 oxidized atoms in chemically grown SiO2 and also amount of carbon contamination. In order to pave the way for further tests of LT-UHV in silicon technology, we present a design of simple UHV instrument. The above-described benefits are reproduced for 4-inch silicon wafers by means of the instrument, which is further utilized to make LT-UHV treatments for complementary SiO2/Si interfaces of the native oxide at silicon diode sidewalls to decrease the reverse bias leakage current of the diodes.Description
Keywords
silicon passivation, wet-chemical oxidation, defect level, surface science
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Citation
Rad, Z J, Lehtiö, J P, Chen, K, Mack, I, Vähänissi, V, Miettinen, M, Punkkinen, M, Punkkinen, R, Suomalainen, P, Hedman, H P, Kuzmin, M, Kozlova, J, Rähn, M, tart, U, Savin, H, Laukkanen, P & Kokko, K 2022, ' Effects of post oxidation of SiO2/Si interfaces in ultrahigh vacuum below 450 °C ', Vacuum, vol. 202, 111134 . https://doi.org/10.1016/j.vacuum.2022.111134
