Direct Growth Properties of Graphene Layers on Sapphire Substrate by Alcohol-Chemical Vapor Deposition

Abstract

Few nanometers thick graphene layers were directly grown on a-plane (112̄0) sapphire substrates by alcohol-chemical vapor deposition (alcohol-CVD) using ethanol as a carbon source and without any catalytic metal on the substrate surface. The growth relationship between the graphene layer and substrate was analyzed using a transmission electron microscope (TEM). The growth rate of graphene layers with different growth temperatures revealed that the Al atom act as a catalyst for synthesizing a graphitic material during the decomposition of ethanol. An optical transmittance and a sheet resistance of the graphene sheet directly grown on sapphire substrate were observed. SiO2/Si and n-6H-SiC substrates were also examined for graphene direct growth to discuss the catalytic behavior of Si atoms compared with Al atoms.

Effect of Growth Pressure on Graphene Direct Growth on an A-Plane Sapphire Substrate: Implications for Graphene-Based Electronic Devices

“…The grain size of graphene was estimated from the D/G ratio as ∼48 nm for the sample grown at 15 kPa and ∼96 nm for the sample grown at 5 kPa, but the real grain size observed by AFM was larger than the estimated ones as described later. The grain size of graphene grown at 5 kPa was larger than the previously reported one of CVD graphene on a-plane sapphire. , Furthermore, the grain size was almost comparable to that of the single-layer graphene grown directly on the c-plane sapphire at ∼1500 °C by Fanton et al…”

“…The grain size of graphene grown at 5 kPa was larger than the previously reported one of CVD graphene on a-plane sapphire. 33,34 Furthermore, the grain size was almost comparable to that of the single-layer graphene grown directly on the c-plane sapphire at ∼1500 °C by Fanton et al 20 The growth time was changed to further investigate the influence of growth pressure on the graphene CVD on a-plane sapphire. Figure 3a shows the growth time changes of the AFM phase images of the samples grown at 5 and 15 kPa for from 15 to 180 min.…”

“…Therefore, the direct graphene growth on a-plane sapphire is very attractive not only for remote epitaxy but also for fabrication of low-cost graphene-based electronic devices. However, the direct growth of graphene on a-plane sapphire is scarcely reported, and no growth mechanism has been sufficiently discussed. , Moreover, the quality of graphene directly grown on sapphire is not yet sufficient because of its small growth grains. Therefore, new approaches to the direct growth of high-quality graphene are strongly desired to improve its qualities.…”

Electrical Characterization of Nanometer Structures with Graphene Directly Grown on SiO₂ by Alcohol Chemical Vapor Deposition

“…Graphene film was directly deposited on SiO 2 /Si substrate by alcohol CVD [2]. The growth conditions are summarized in Table 1.…”

“…Graphene has attracted much attention owing to its unique band structure and excellent transport characteristics [1]. Among various preparation methods of graphene, direct growth on insulator without transfer process [2] is of practical importance, but electrical characterization in nanometer regime has lagged behind since higher priority is set in improving the basic property such as carrier mobility. In this report, characteristics of graphene directly grown on SiO 2 by alcohol chemical vapor deposition (CVD) are evaluated in nanometer structures.…”