Strong Fermi-Level Pinning in GeS-Metal Nanocontacts

Yuxuan Sun, Zhen Jiao*, Harold J.W. Zandvliet, Pantelis Bampoulis

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Germanium sulfide (GeS) is a layered monochalcogenide semiconductor with a band gap of about 1.6 eV. To verify the suitability of GeS for field-effect-based device applications, a detailed understanding of the electronic transport mechanisms of GeS-metal junctions is required. In this work, we have used conductive atomic force microscopy (c-AFM) to study charge carrier injection in metal-GeS nanocontacts. Using contact current-voltage spectroscopy, we identified three dominant charge carrier injection mechanisms: thermionic emission, direct tunneling, and Fowler-Nordheim tunneling. In the forward-bias regime, thermionic emission is the dominating current injection mechanism, whereas in the reverse-bias regime, the current injection mechanism is quantum mechanical tunneling. Using tips of different materials (platinum, n-type-doped silicon, and highly doped p-type diamond), we found that the Schottky barrier is almost independent of the work function of the metallic tip, which is indicative of a strong Fermi-level pinning. This strong Fermi-level pinning is caused by charged defects and impurities.

Original languageEnglish
Pages (from-to)11400-11406
Number of pages7
JournalThe Journal of physical chemistry C
Issue number27
Publication statusPublished - 14 Jul 2022


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