A1 Refereed original research article in a scientific journal
Passivation of Germanium Surfaces by HF:H2O2 Aqueous Solution
Authors: Terletskaia, Mariia; Isometsä, Joonas; Miettinen, Mikko; Laukkanen, Pekka; Vähänissi, Ville; Savin, Hele
Publisher: WILEY-V C H VERLAG GMBH
Publishing place: WEINHEIM
Publication year: 2025
Journal: physica status solidi (RRL) - Rapid Research Letters
Journal name in source: PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
Journal acronym: PHYS STATUS SOLIDI-R
Article number: 2400297
Volume: 19
Issue: 3
Number of pages: 6
ISSN: 1862-6254
eISSN: 1862-6270
DOI: https://doi.org/10.1002/pssr.202400297
Web address : https://doi.org/10.1002/pssr.202400297
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/485056778
Promising intrinsic electronic properties, such as narrow bandgap and high charge carrier mobilities, make germanium (Ge) a good replacement for silicon in optoelectronic applications (e.g., photodetectors). However, successful fabrication of efficient Ge devices requires minimization of both reflectance and surface recombination losses. This work begins with an observation that metal-assisted chemical etching (MACE) of Ge surfaces, used for optics improvement, reduces surface recombination without application of any intentional passivation. We proceed with investigation of the effect of MACE solution components and their mixtures on Ge surface passivation. The results demonstrate that HF:H2O2 aqueous solution leads to efficient and stable passivation. The film formed in this solution secures surface recombination velocity (Seff) of 14 cm s-1. Morphological and chemical characterization of the structure reveals porous germanium (PGe) layer with some GeOx included. Finally, we propose several hypotheses on a mechanism behind this passivation, among which are the presence of GeO2 at the film-bulk Ge interface and appearance of a potential barrier due to the heterojunction formation. The presented Ge passivation with PGe layer provides a simple and cost-efficient alternative to existing state-of-the-art passivation schemes.
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Funding information in the publication:
The authors thank the Research Council of Finland (project nos. 331313 and 338974) for financial support. The authors also thank the Finnish Ministry of Education and Culture for financial support within the pilot project MIcroELectronics doctoral school pilot (MIELi) for doctoral program (project no. VN/3137/2024-OKM-6). The work was also related to the Flagship on Photonics Research and Innovation “PREIN” funded by the Research Council of Finland, decision number 346529. The authors acknowledge the provision of facilities and technical support by the Micronova Nanofabrication Centre in Espoo, Finland, within the OtaNano research infrastructure at Aalto University.
