Graphene nanoribbons initiated from molecularly derived seeds

Abstract

Semiconducting graphene nanoribbons are promising materials for nanoelectronics but are held back by synthesis challenges. Here we report that molecular-scale carbon seeds can be exploited to initiate the chemical vapor deposition (CVD) synthesis of graphene to generate one-dimensional graphene nanoribbons narrower than 5 nm when coupled with growth phenomena that selectively extend seeds along a single direction. This concept is demonstrated by subliming graphene-like polycyclic aromatic hydrocarbon molecules onto a Ge(001) catalyst surface and then anisotropically evolving size-controlled nanoribbons from the seeds along $$\left\langle 110\right\rangle$$ 110 of Ge(001) via CH4 CVD. Armchair nanoribbons with mean normalized standard deviation as small as 11% (3 times smaller than nanoribbons nucleated without seeds), aspect ratio as large as 30, and width as narrow as 2.6 nm (tunable via CH4 exposure time) are realized. Two populations of nanoribbons are compared in field-effect transistors (FETs), with off-current differing by 150 times because of the nanoribbons’ different widths.

Full analytical solution of finite-length armchair/zigzag nanoribbons

“…Experimentally, bottom-up techniques have enabled the fabrication of long armchair GNRs of different widths and finite length from molecular precursors with atomic precision. [5][6][7][8][9][10] The existence of edge states at the zigzag ends of some of these ribbons has been confirmed by scanning tunneling microscopy, 7 while transport measurements have demonstrated their magnetic character. 11 From the theoretical point of view, the existence of edge states localized at the zigzag edges of GNRs [12][13][14][15][16][17][18] and graphene islands of different shapes 19 was predicted long time ago.…”

Full analytical solution of finite-length armchair/zigzag nanoribbons

“…In particular, graphene nanoribbons (GNRs) keep attracting attention due to their characteristic electronic and magnetic properties, usually related to the presence of topologically protected edge states around their zigzag terminations. Experimentally, bottom-up techniques have enabled the fabrication of long armchair GNRs of different widths and finite length from molecular precursors with atomic precision [5][6][7][8][9][10]. The existence of edge states at the zigzag ends of some of these ribbons has been confirmed by scanning tunneling microscopy [7], while transport measurements have demonstrated their magnetic character [11].…”

Ultralong, High Aspect Ratio Graphene Nanoribbon Arrays Fabricated by Laser Interference Lithography: Implications for Integrated Nanocircuits

“…In contrast, methods like CVD and chemical assembling from small molecules can achieve mass production of GNRs with high uniformity, but the length of obtained GNRs is usually limited within 1 μm. 13 Nanowire mask lithography or chemical etching can achieve the designed GNRs. However, since the mask/nanomaterial base is normally needed, it can also be very limited for the fabrication of diversified structures.…”

“…Subtractive manufacturing methods like EBL, FIB, and electro-erosion have been reported for high-precision individual GNR fabrication in designated shape with controlled length and width, while the low productivity impedes their further application. In contrast, methods like CVD and chemical assembling from small molecules can achieve mass production of GNRs with high uniformity, but the length of obtained GNRs is usually limited within 1 μm . Nanowire mask lithography or chemical etching can achieve the designed GNRs.…”

“…Much effort has been made for GNR fabrication, such as chemical vapor deposition (CVD), 13 electron beam lithography (EBL), 14 focused ion beam (FIB) milling, 15 electroerosion, 16 nanowire mask lithography, 17 and chemical etching. 18 Subtractive manufacturing methods like EBL, FIB, and electro-erosion have been reported for high-precision individual GNR fabrication in designated shape with controlled length and width, while the low productivity impedes their further application.…”