Direct growth of graphene on Ge(100) and Ge(110) via thermal and plasma enhanced CVD

Abstract

The integration of graphene into CMOS compatible Ge technology is in particular attractive for optoelectronic devices in the infrared spectral range. Since graphene transfer from metal substrates has detrimental effects on the electrical properties of the graphene film and moreover, leads to severe contamination issues, direct growth of graphene on Ge is highly desirable. In this work, we present recipes for a direct growth of graphene on Ge via thermal chemical vapor deposition (TCVD) and plasma-enhanced chemical vapor deposition (PECVD). We demonstrate that the growth temperature can be reduced by about 200 °C in PECVD with respect to TCVD, where usually growth occurs close to the melting point of Ge. For both, TCVD and PECVD, hexagonal and elongated morphology is observed on Ge(100) and Ge(110), respectively, indicating the dominant role of substrate orientation on the shape of graphene grains. Interestingly, Raman data indicate a compressive strain of ca. − 0.4% of the graphene film fabricated by TCVD, whereas a tensile strain of up to + 1.2% is determined for graphene synthesized via PECVD, regardless the substrate orientation. Supported by Kelvin probe force measurements, we suggest a mechanism that is responsible for graphene formation on Ge and the resulting strain in TCVD and PECVD.

Graphene Synthesis: Method, Exfoliation Mechanism and Large-Scale Production

“…The construction methods are based on the vaporization, pyrolysis, and reaction of low-boiling organics under high-energy effects such as the laser [18], microwave [19], plasma [20], pulsed laser deposition (PLD) [21][22][23], used to deposit or precipitate carbon atoms on the surface of the substrate. After the induced nucleation, growth, crystallization, or rearrangement, large-size single-layer and few-layer graphenes are finally obtained.…”

Tracking Interfacial Changes of Graphene/Ge(110) During In-Vacuum Annealing

“…In this context, Germanium (Ge) has emerged as a promising alternative growth substrate for direct CVD growth of graphene [11][12][13][14]. The lack of stability of Ge carbides together with the low carbon solubility in Ge enables the controlled synthesis of graphene on the Ge(001), Ge(110) and Ge(111) surfaces [15][16][17][18][19][20]. However, on Ge(001), the growth of high-quality graphene is typically accompanied by the faceting of the Ge substrate along shallow crystal orientations vicinal to the (001) face [14,21], likely triggered by the well-known existence of several surface-energy minima around Ge(001) [22].…”

Freestanding Graphene Fabric Film for Flexible Infrared Camouflage

“…The as‐fabricated graphene film owns merits of high quality and high uniformity. [ 16 , 17 , 18 , 19 ] But the tight integration between graphene film and substrate limits further structure design, while the inevitable tedious transfer process could also cause defects and degrade the properties of graphene. [ 20 , 21 , 22 , 23 , 24 , 25 ]…”

“…The as-fabricated graphene film owns merits of high quality and high uniformity. [16][17][18][19] But the tight integration between graphene film and substrate limits further structure design, while the inevitable tedious transfer process could also cause defects and degrade the properties of graphene. [20][21][22][23][24][25] Herein, by virtue of our graphene growth experience on SiO 2 fiber by CVD method, [26][27][28] a flexible papyraceous freestanding graphene fabric film (FS-GFF) was designed.…”