Refereed journal article or data article (A1)

Effects of post oxidation of SiO2/Si interfaces in ultrahigh vacuum below 450 °C




List of AuthorsJahanshah Rad Zahra, Lehtiö Juha-Pekka, Chen Kexun, Mack Iris, Vähänissi Ville, Miettinen Mikko, Punkkinen Marko, Punkkinen Risto, Suomalainen Petri, Hedman Hannu-Pekka, Kuzmin Mikhail, Kozlova Jekaterina, Rähn Mihkel, Tamm Aile, Savin Hele, Laukkanen Pekka, Kokko Kalevi

PublisherElsevier Ltd

Publication year2022

JournalVacuum

Journal name in sourceVacuum

Article number111134

Volume number202

ISSN0042-207X

eISSN1879-2715

DOIhttp://dx.doi.org/10.1016/j.vacuum.2022.111134

URLhttps://doi.org/10.1016/j.vacuum.2022.111134

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/175546227


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 °C. 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.

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Last updated on 2023-15-06 at 16:07