Plasma-enhanced chemical vapor deposition synthesis of vertically oriented graphene nanosheets

Abstract

Vertically oriented graphene (VG) nanosheets have attracted growing interest for a wide range of applications, from energy storage, catalysis and field emission to gas sensing, due to their unique orientation, exposed sharp edges, non-stacking morphology, and huge surface-to-volume ratio. Plasma-enhanced chemical vapor deposition (PECVD) has emerged as a key method for VG synthesis; however, controllable growth of VG with desirable characteristics for specific applications remains a challenge. This paper attempts to summarize the state-of-the-art research on PECVD growth of VG nanosheets to provide guidelines on the design of plasma sources and operation parameters, and to offer a perspective on outstanding challenges that need to be overcome to enable commercial applications of VG. The review starts with an overview of various types of existing PECVD processes for VG growth, and then moves on to research on the influences of feedstock gas, temperature, and pressure on VG growth, substrate pretreatment, the growth of VG patterns on planar substrates, and VG growth on cylindrical and carbon nanotube (CNT) substrates. The review ends with a discussion on challenges and future directions for PECVD growth of VG.

Controllable Synthesis of Graphene by Plasma‐Enhanced Chemical Vapor Deposition and Its Related Applications

“…for several years. Since surface‐bound vertically oriented carbon nanosheets were initially discovered by direct current (dc) arc discharge evaporation of graphite,69 PECVD with different plasma sources such as MW plasma,70, 71 dc plasma,72, 73, 74 RF plasma,65, 75, 76, 77 their combinations with different reactor configurations78, 79, 80 have also been used for the growth of VG nanosheets. The morphology and structure of VG nanosheers produced by PECVD are strongly dependent on the types of plasma sources66, 67, 73, 79, 81, 82, 83 and a series of operating parameters, including the feedstock gas type84, 85, 86, 87 (CH x ( x = 1–3), CF 4 , CHF 3 , or C 2 F 6 ), gas composition and proportion,69, 86, 88, 89 the substrate species90 and temperature,75, 76, 80, 91 the operating pressure73, 76 and the growth time,75, 76 and the plasma power 67, 76, 92…”

“…The effective removal of a‐C has been widely recognized as a crucial and inevitable step to the formation of high‐quality nuclei, and then further vertically grown VG nanosheets 67, 79. Several atoms and radicals play a key role in VG nanosheet growth.…”

Synthesis of Vertical Graphene by Microwave Plasma Enhanced Chemical Vapor Deposition Technique

“…Graphene, an isolated planar carbon sheet composed of a sp 2 bonded honeycomb lattice is currently considered as one of the important materials due to its unique properties such as high electron mobility, high thermal conductivity and high mechanical strength [2]. Both horizontal and vertical oriented graphene have been reported in the literature [3,4]. The properties of graphene depend upon the number of layers presented and their stacking.…”

“…Recently, many researchers have shown interest in vertical oriented graphene due to their high surface-to-volume ratio compared to horizontal graphene. High surface-to-volume ratio is very much desirable for field emitters, gas sensors and biosensors applications [3].…”

Synthesis of Nanostructure Carbon Films Deposited by Microwave Plasma-Enhanced Chemical Vapor Deposition Technique at Room Temperature

“…Therefore, lowering the processing temperature of carbon-based nanostructure is currently the focus of research worldwide. Recently, carbon nanosheets are of significant interest as they may contain many graphene layers (4,5). Thomas and Rao (6) while synthesizing erected carbon sheets at very high temperature of about 800 C by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVD) found crumpled like semi-transparent sheets like structure on copper substrate.…”