Preparation of Chemical Vapor-deposited Materials for Use in Field-enhanced Electron Emission Studies

Preparation of Chemical Vapor-deposited Materials for Use in Field-enhanced Electron Emission Studies
Author: David G. MCMaster
Publisher:
Total Pages: 44
Release: 1966
Genre:
ISBN:

The general principles of chemical vapor deposition (CVD) are described and specific experimental results on the deposition of pyrolytic graphite, of CVD boron nitride, and of CVD tungsten on tungsten substrates are discussed. In order to obtain uniform anisotropic, thin films of pyrolytic graphite and CVD boron nitride, the deposition parameters such as deposition temperature, concentration of the gaseous reactants, and gas flow pattern were varied, and their influence on the deposits was studied. It was found that the uniformity of pyrolytic graphite can be increased by using high total gas flow rates and low methane concentrations. The most uniform CVD-boron nitride deposits were obtained under the following conditions: Temperature: 1600C; Gas flow rate (cc/min): ammonia 10, boron trichloride 6, nitrogen 4. The deposits of pyrolytic graphite and CVD boron nitride exhibited a high degree of anisotropy. Thin-film sandwich structures of pyrolytic graphite and CVD boron nitride were successfully produced. Preliminary tests have been performed with CVD tungsten. (Author).

Chemical Vapor Deposition Growth and Characterization of Two-Dimensional Hexagonal Boron Nitride

Chemical Vapor Deposition Growth and Characterization of Two-Dimensional Hexagonal Boron Nitride
Author: Roland Yingjie Tay
Publisher: Springer
Total Pages: 152
Release: 2018-06-20
Genre: Technology & Engineering
ISBN: 9811088098

This thesis focuses on the growth of a new type of two-dimensional (2D) material known as hexagonal boron nitride (h-BN) using chemical vapor deposition (CVD). It also presents several significant breakthroughs in the authors’ understanding of the growth mechanism and development of new growth techniques, which are now well known in the field. Of particular importance is the pioneering work showing experimental proof that 2D crystals of h-BN can indeed be hexagonal in shape. This came as a major surprise to many working in the 2D field, as it had been generally assumed that hexagonal-shaped h-BN was impossible due to energy dynamics. Beyond growth, the thesis also reports on synthesis techniques that are geared toward commercial applications. Large-area aligned growth and up to an eightfold reduction in the cost of h-BN production are demonstrated. At present, all other 2D materials generally use h-BN as their dielectric layer and for encapsulation. As such, this thesis lays the cornerstone for using CVD 2D h-BN for this purpose.