Width-dependent band gap of arm-chair graphene nanoribbons formed on vicinal SiC substrates by MBE

Takushi Iimori; Toshio Miyamachi; Takashi Kajiwara; Kazuhiko Mase; Satoru Tanaka; Fumio Komori; Kan Nakatsuji

doi:10.1088/1361-648X/aced30

Width-dependent band gap of arm-chair graphene nanoribbons formed on vicinal SiC substrates by MBE

J Phys Condens Matter. 2023 Aug 15;35(45). doi: 10.1088/1361-648X/aced30.

Authors

Takushi Iimori¹, Toshio Miyamachi¹, Takashi Kajiwara², Kazuhiko Mase^{3

4}, Satoru Tanaka², Fumio Komori^{1

5}, Kan Nakatsuji⁵

Affiliations

¹ Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
² Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395, Japan.
³ Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan.
⁴ Department of Materials Structure Science, SOKENDAI (The Graduate University for Advanced Studies), Tsukuba, Ibaraki 305-0801, Japan.
⁵ School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8502, Japan.

PMID: 37536324
DOI: 10.1088/1361-648X/aced30

Abstract

Formation and electronic states of graphene nanoribbons with arm-chair edges (AGNR) are studied on the SiC(0001) vicinal surfaces toward the [11-00] direction. The surface step and terrace structures of both 4H and 6H-SiC substrates are used as the growth templates of one-dimensional arrays of AGNRs, which are prepared using the carbon molecular beam epitaxy followed by hydrogen intercalation. A band gap is observed above theπ-band maximum by angle-resolved photoelectron spectroscopy (ARPES) for the both samples. The average widths of the AGNRs are 6 and 10 nm, and the estimated average band gaps are 0.40 and 0.28 eV for the 4H- and 6H- substrates, respectively. A simple and phenomenological inverse relation between the energy gap and AGNR width works in the analyses of the ARPES data.

Keywords: angle-resolved photoelectron spectroscopy; graphene; molecular beam epitaxy; nano ribbon.