Partial Pressure Assisted Growth of Single-Layer Graphene Grown by Low-Pressure Chemical Vapor Deposition: Implications for High-Performance Graphene FET Devices

Abstract

An attempt has been made to understand the thermodynamic mechanism study of the low-pressure chemical vapor deposition (LPCVD) process during single-layer graphene (SLG) growth as it is the most debatable part of the CVD process. The intensive studies are being carried out worldwide to enhance the quality of LPCVD-grown graphene up to the level of mechanically exfoliated SLG. The mechanism and processes have been discussed earlier by several research groups during the variation in different parameters. However, the optimization and mechanism involvement due to individual partial pressure-based effects has not been elaborately discussed so far. Hence, we have addressed this issue in detail including thermodynamics of the growth process and tried to establish the effect of the partial pressures of individual gases during the growth of SLG. Also, optical microscopy, Raman spectroscopy, and atomic force microscopy (AFM) have been performed to determine the quality of SLG. Furthermore, nucleation density has also been estimated to understand a plausible mechanism of graphene growth based on partial pressure. Moreover, the field-effect transistor (FET) device has been fabricated to determine the electrical properties of SLG, and the estimated mobility has been found as ∼2595 cm 2 V –1 s –1 at n = −2 × 10 12 cm –2 . Hence, the obtained results trigger that the partial pressure is an important parameter for the growth of SLG and having various potential applications in high-performance graphene FET (GFET) devices.

Effect of Ni atomic fraction on active species of graphene growth on Cu–Ni alloy catalysts: a density functional theory study

“…35,36 In addition, pure Cu(111) catalyst has been widely used to grow graphene. 24,[50][51][52] The high density of surface atoms on Cu(111) induces a high carbon atom diffusion rate, promoting a high graphene growth rate. 50 The Cu(111) surface also has a lattice constant similar to graphene, resulting in a low lattice mismatch.…”

“…79 Experimental results have also shown that it is difficult to diffuse a carbon monomer into the Cu catalyst because of its low carbon solubility. 21,24 In addition, the Cu-Ni-1 catalyst behaves similarly to the Cu catalyst because the atomic fraction of Ni is low, but the adsorption energy difference between the surface and first subsurface is insignificant. The Cu-Ni-2 and Cu-Ni-3 catalysts behave differently from the Cu and Cu-Ni-1 catalysts: the adsorption on the subsurface is more stable than surface adsorption.…”

“…Generally, graphene growth using the CVD method is conducted in a temperature range of 600-1200 1C. 21,24,36 Therefore, we calculate the relative population of carbon source species over a temperature range of 600-1200 1C and an H 2 partial pressure of 10 À2 torr, as shown in Fig. 12.…”

“…[20][21][22] However, due to the low solubility of carbon atoms, the self-limiting growth mechanism prevents the growth of multilayer graphene on the Cu catalyst. 23,24 Another conventional catalyst used for graphene growth is nickel. 25,26 However, the high solubility of carbon atoms in Ni induces cooling-induction segregation growth, which tends to produce non-uniform multilayer graphene.…”

“…46,47 Besides metal-carbon interactions, growth conditions such as temperature and H 2 partial pressure also affect the stability of the carbon source species. 21,22,24,30 Experimentally, temperature increases the growth rate. 21 In addition, H 2 is included during CVD growth because it has two roles: first, it controls the size and morphology of the graphene domain because of its etching reagent ability, and second, it acts as an activator for carbon that is bonded to the catalyst.…”