Understanding the growth mechanism of graphene on Ge/Si(001) surfaces

Abstract

The practical difficulties to use graphene in microelectronics and optoelectronics is that the available methods to grow graphene are not easily integrated in the mainstream technologies. A growth method that could overcome at least some of these problems is chemical vapour deposition (CVD) of graphene directly on semiconducting (Si or Ge) substrates. Here we report on the comparison of the CVD and molecular beam epitaxy (MBE) growth of graphene on the technologically relevant Ge(001)/Si(001) substrate from ethene (C2H4) precursor and describe the physical properties of the films as well as we discuss the surface reaction and diffusion processes that may be responsible for the observed behavior. Using nano angle resolved photoemission (nanoARPES) complemented by transport studies and Raman spectroscopy as well as density functional theory (DFT) calculations, we report the direct observation of massless Dirac particles in monolayer graphene, providing a comprehensive mapping of their low-hole doped Dirac electron bands. The micrometric graphene flakes are oriented along two predominant directions rotated by 30° with respect to each other. The growth mode is attributed to the mechanism when small graphene “molecules” nucleate on the Ge(001) surface and it is found that hydrogen plays a significant role in this process.

Direct CVD Growth of Graphene on Technologically Important Dielectric and Semiconducting Substrates

“…Dabrowski et al presented a detailed understanding of direct CVD growth mechanism of graphene on Ge (001)/Si (001) substrates 132. Prior to the graphene growth, 2 µm thick Ge (001) layers were grown on 200 mm Si (001) wafers by CVD 130, 133.…”

“…The typical heights of the facets and R a values were found to be 2–5 nm and 0.7–1.1 nm, respectively [from AFM image (Figure 17g)]. Generally, the majority of crystallites are oriented either parallel or perpendicular to the (110) axis in the CVD graphene on Ge (001), where the carbon hexagons have sides either parallel or perpendicular to the surface dimer rows (Figure 17h) 121, 123, 131, 132. It could be possible that the small graphene grains with the same orientation could coalesce into larger strained grains, however their sizes will be limited by the distance between surface steps, as the growth direction rotates by 90° from terrace to terrace.…”

Electrochemical Sensors and Biosensors Based on Graphene Functionalized with Metal Oxide Nanostructures for Healthcare Applications

“…The researchers likewise established that the manufactured graphene flakes might be transported to additional substrates. To satisfy the unusual requirements, non‐metal constituents such as Si,, SiO 2, , and BN, were also used as substrates. However, non‐metal substrates exhibited disadvantageous restrictions together with deliberate evolution proportion and intermittent dimensions.…”

Graphene-Paper Based Electrochemical Sensors

“…The graphene films obtained by CVD methods displayed high flexibility, transparency and electrical conductivity [12,13], which is attractive for various electronic devices. Commonly, transition metals, such as Ge [14,15], Ni [16,17], Cu [18,19], Rh [20][21][22] and Co [23,24], are used as the substrates for the CVD growth of graphene films. Due to very low carbon solubility in Cu, ease of etching and feasibility of high-quality graphene transfer, Cu has emerged as a favoured substrate chosen mostly for the growth of large-area graphene films [25], which was first introduced by Ruoff's research group in 2009 [13].…”

“…They also demonstrated that as-synthesized graphene films could be transferred to other substrates (Figure 1b and c). To meet some special requirements, non-metal materials, such as Si [14,15], SiO 2 [26][27][28], BN [29,30] and Si 3 N 4 [31,32], were also used as substrates. However, the non-metal substrates showed the drawback limitations including slow growth rate and discontinuous size.…”