Doctoral Dissertations

Abstract

"A study of the chemical vapor deposition (CVD) of boron from boron triiodide (BI3) on molybdenum has been done with field emission microscopy (FEM) and low energy electron diffraction (LEED).

A correlation of the efficiency by which BI3 is effectively dissociated to form adsorbed boron, and the temperature of the substrate has been shown through work function measurements on the boron covered molybdenum field emitter surfaces. The boron-induced work function change of molybdenum has been shown to be in agreement with a theoretical model which predicts positive, as well as negative work functions for adsorbate-substrate systems. It has previously been found that the theoretical model can be used to accurately determine the occurence of the adsorbate monolayer. By comparison of the experimental work function data with the theoretical model inferrence of the thermal accommodation coefficient, of the adsorbate source species (BI3), on the substrate is made.

The free energy of desorption of boron from molybdenum field emitter surfaces has been measured by isothermal desorption experiments and been found to be 46.9 kcal/mole at boron coverages of about 0.4 monolayer.

The time-dependent adsorption, leading to nucleation of boron on molybdenum field emitter surfaces has been observed to occur at about 0.5 monolayer coverages of boron.

LEED studies of a Mo(100) single crystal at substrate temperatures of 700°C to 900°C in BI3 partial pressures of 3 x 10-8 torr result in no structure change relative to the clean surface, even at prolonged exposures to BI3. However, under the same experimental conditions, the Mo(110) surface exhibits the formation of one-dimensional disordered structures with the original ordering maintained in an orthogonal direction to the disorder"--Abstract, pages ii-iii.

Advisor(s)

Ownby, P. D.

Committee Member(s)

Sorrell, Charles A.
Levenson, L. L., 1928-1998
Moore, Robert E., 1930-2003
Bell, Robert John, 1934-

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Ceramic Engineering

Publisher

University of Missouri--Rolla

Publication Date

1973

Pagination

x, 118 pages

Note about bibliography

Includes bibliographical references.

Rights

© 1973 Richard Eugene Moore, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Chemical vapor deposition
Chemical kinetics
Boron
Molybdenum

Thesis Number

T 2813

Print OCLC #

6024893

Electronic OCLC #

913834812

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