Graphene Induced Diamond Nucleation on Tungsten

Chih-Chun Chang,Yonhua Tzeng

doi:10.1109/ojnano.2020.3038055

Chih-Chun Chang, Yonhua Tzeng

Open Access

https://doi.org/10.1109/ojnano.2020.3038055

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Abstract

Chemical vapor deposition (CVD) of a diamond film on a non-diamond substrate begins with the insertion of diamond seeds or the formation of diamond nuclei on the substrate. For the deposition of a smooth, large-area and pin-hole free diamond film that adheres well to the substrate, diamond seeds or nuclei need to be of high density, uniformly distributed and adhere well to the substrate. Diamond seeding is not a diamond nucleation process. Bias enhanced nucleation (BEN) is the most effective means of heterogeneous nucleation of diamond for CVD diamond. It is based on a negative biasing voltage between the substrate and the diamond CVD plasma to accelerate positive ions from the plasma to bombard the substrate. Both direct diamond seeding and BEN have technical barriers in practical applications. New diamond nucleation techniques are desired. This paper reports novel heterogenous diamond nucleation along edge line of graphene on tungsten leading to the deposition of continuous diamond films. Based on experimental observation, a diamond nucleation mechanism assisted by sp3 C-W bonds at graphene edge is proposed. It is wished that scientists will become interested in revealing the precise diamond nucleation mechanism. With that, further optimization of this invention may lead to a new, complementary diamond nucleation process for practical deposition of diamond films.

Highlights

Diamonds exhibit many desirable properties, making them very promising materials [1]–[10]
The monolayer graphene exhibits a G-band at 1586 cm−1 and a 2D-band at 2680 cm−1 with little D-band signal in the Raman spectrum excited by a 532-nm laser
The Raman spectrum and the well-studied self-limiting surface diffusion model for graphene synthesis on copper by thermal chemical vapor deposition (CVD) indicate that the graphene is monolayer and of high quality [55]

Summary

Introduction

Diamonds exhibit many desirable properties, making them very promising materials [1]–[10]. Sp bonded diamond is metastable while graphite is stable at atmospheric pressure and below. This makes the growth of diamond in laboratory chemical vapor deposition (CVD) reactors challenging [11]–[20]. 3-D graphite and 2-D graphene are sp bonded carbon materials [21]–[23], which are thermodynamically stable at atmospheric pressure and below, making them easier than diamond to grow by laboratory CVD reactors. In order to deposit uniform, smooth, pin-hole free and large-area diamond films on non-diamond substrates by CVD techniques, it is necessary to either insert firmly diamond nanoparticles into the substrates or form diamond nuclei on the substrates. Uniform and high-density diamond seeds or diamond nuclei are prerequisite. Diamond seeding is effective for depositing CVD diamond films for many applications.

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