Document Type

Thesis

Date of Award

8-31-1986

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical Engineering

First Advisor

Roy H. Cornely

Second Advisor

Marek Sosnowski

Abstract

Gallium thin films were deposited by Ion Cluster Beam (ICB) from pure gallium. This research had two objectives: to develop a practical method of crucible heating to generate gallium clusters; and to investigate the influence of ICB system parameters on the formation of clusters and film properties. An electron-bombardment crucible heater with a novel construction was designed. The top section of the carbon crucible was kept at a higher temperature than the middle section to prevent clogging of the nozzle and " spitting " phenomena which were found to occur with the conventional design. Crucible temperatures up to about 1360°C were thus obtained.

It was found that the growth of gallium films was under the strong influence of the ionization current; the higher the degree of ionization, the higher the degree of film crystallinity. It also was found that less efficient ionization, due to a decrease in the effective cluster ionization cross section with electron velocity, occurred for ionization stage voltages above 100 volts. From the cluster charge and mass deposition measurements, it appeared that clusters were not generated at crucible temperatures less than 1100°C. This suggested that for gallium clusters to be generated, with the nozzle source used in these experiments, the gallium vapor pressure in the crucible must be greater than 0.2 Torr.

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