Document Type
Thesis
Date of Award
5-31-1988
Degree Name
Master of Science in Electrical Engineering - (M.S.)
Department
Electrical Engineering
First Advisor
Roy H. Cornely
Second Advisor
W. H. Warren Ball
Abstract
The objective of this research was the design and construction of an experimental apparatus to investigate the size distribution of gallium clusters that can be emitted from a heated crucible with a 1 mm nozzle. This research work involved the design and construction of a partially ionized cluster beam (PICB) deposition system which would provide low charged particle background for retarding field analysis and cluster size measurements. The apparatus also allowed control of critical parameters on which the cluster size may depend.
The promise of PICB is based on the formation of clusters of adatoms, their ionization and their acceleration at a substrate and the utilization of the ideal energies (1 to 10 eV) that the adatoms could have when clusters break up upon impact with the substrate. To control the energy of the adatoms, the cluster size must be known, which was the driving force for this thesis work.
Although good film results have been reported with conventional PICB equipment, the equipment was not designed for precise ion current beam measurements. A major accomplishment of this research work was the design and construction of an efficient electron beam heating system capable of providing both an empty nozzle temperature of 2000°C and a low charged particle background current of the order of 1 nA. The charge and mass measurements at a crucible temperature of 1450° C, corresponding to a gallium equilibrium vapor pressure of 5 torr, showed that clusters of more than a few atoms were not present under the specific crucible conditions used in the experiment. According to heterogeneous cluster formation theory, which considers nucleation on the colder upper crucible surface, variation of temperature along the inside crucible walls has a strong influence on the cluster formation and size distribution. The thesis work led to the conclusion that a two filament electron gun should be used to control the axial distribution of electrons bombarding the crucible walls and the axial temperature profile.
Recommended Citation
Shah, Nitin K., "Design of an experimental apparatus to measure the charge and mass of ionized species in a partially ionized cluster beam deposition system" (1988). Theses. 3207.
https://digitalcommons.njit.edu/theses/3207
