A1 Journal article – refereed
Decreasing Interface Defect Densities via Silicon Oxide Passivation at Temperatures Below 450 degrees C
List of Authors: Jahanshah Rad Zahra, Lehtiö Juha-Pekka, Mack Iris, Rosta Kawa, Chen Kexun, Vähänissi Ville, Punkkinen Marko, Punkkinen Risto, Hedman Hannu-Pekka, Pavlov Andrei, Kuzmin Mikhail, Savin Hele, Laukkanen Pekka, Kokko Kalevi
Publisher: AMER CHEMICAL SOC
Publication year: 2020
Journal: ACS Applied Materials and Interfaces
Journal name in source: ACS APPLIED MATERIALS & INTERFACES
Journal acronym: ACS APPL MATER INTER
Volume number: 12
Issue number: 41
Number of pages: 9
ISSN: 1944-8244
eISSN: 1944-8252
DOI: http://dx.doi.org/10.1021/acsami.0c12636
Low-temperature (LT) passivation methods (<450 degrees C) for decreasing defect densities in the material combination of silica (SiOx) and silicon (Si) are relevant to develop diverse technologies (e.g., electronics, photonics, medicine), where defects of SiOx/Si cause losses and malfunctions. Many device structures contain the SiOx/Si interface(s), of which defect densities cannot be decreased by the traditional, beneficial high temperature treatment (>700 degrees C). Therefore, the LT passivation of SiOx/Si has long been a research topic to improve application performance. Here, we demonstrate that an LT (<450 degrees C) ultrahigh-vacuum (UHV) treatment is a potential method that can be combined with current state-of-the-art processes in a scalable way, to decrease the defect densities at the SiOx/Si interfaces. The studied LT-UHV approach includes a combination of wet chemistry followed by UHV-based heating and preoxidation of silicon surfaces. The controlled oxidation during the LT-UHV treatment is found to provide an until now unreported crystalline Si oxide phase. This crystalline SiOx phase can explain the observed decrease in the defect density by half. Furthermore, the LT-UHV treatment can be applied in a complementary, post-treatment way to ready components to decrease electrical losses. The LT-UHV treatment has been found to decrease the detector leakage current by a factor of 2.
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