Plasma CVD Synthesis of graphene nanoribbon quantum dot devices with temperature-stable orbital-level spacing

We have demonstrated the scalable fabrication of graphene nanoribbon (GNR)-based quantum dot devices by advanced plasma CVD [1-4]. Systematic investigation revealed that fine structures are formed at the middle of the GNRs, resulting in the quantum-dot features of our GNRs. Detailed measurements at cryogenic temperatures revealed clear orbital-level spacings between the ground state and excited states in our GNR-based quantum-dot device. Furthermore, the orbital levels were found to be very stable even at high-temperature conditions (~20 K), which can be explained by the very fine structures formed in the middle of the GNR and relatively light effective mass of the GNR. More than 18% of devices fabricated within the same substrate showed orbital levels, indicating that integration of GNR-based quantum-dot devices is possible with our method.

[1] T. Kato and R. Hatakeyama, Nature Nanotechnology 7 (2012) 651. [2] H. Suzuki, T. Kaneko, Y. Shibuta, M. Ohno, Y. Maekawa, and T. Kato, Nature Communications 7 (2016) 11797. [3] H. Suzuki, N. Ogura, T. Kaneko, T. Kato, Scientific Reports 8 (2018) 11819. [4] Q.-Y. Li, T. Feng, W. Okita, Y. Komori, H. Suzuki, T. Kato, T. Kaneko, T. Ikuta, X. Ruan, K. Takahashi, ACS Nano 13 (2019) 9182.