Document Type

Thesis

Date of Award

6-30-1962

Degree Name

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

Department

Chemical Engineering

First Advisor

C. L. Mantell

Second Advisor

Joseph Joffe

Third Advisor

Saul I. Kreps

Abstract

Oxide films of lead, tellurium, and their alloys were deposited by reactive sputtering onto substrates and analyzed by X-ray emission spectrography. The sputtering process involved the bombardment of a metallic cathode with positive ions in an atmosphere containing oxygen. The preparation and analysis of these films are described. The unstrained, homogeneous films have good adherence to the substrate and may be prepared to arbitrary thicknesses. Over a range of lead-tellurium oxide compositions these films are transparent and are glassy, rather than crystalline or amorphous solids.

From the analyses of the films by X-ray emission spectrography and known cathode compositions, it was established that the ratio of lead to tellurium in the deposited material is essentially the same as that in the alloy cathode. The sputtering yields and deposition rates were evaluated as functions of ion energy and observed to be independent of cathode composition. The deposition rates achieved maximum values at about 1500 ev and then decreased with further increases in ion energy, even though the sputtering yields continued to increase. The rates determined for sputtering representative cathodes in oxygen plus argon mixtures and pure argon are compared with the values measured for processes conducted in pure oxygen. Data obtained from preliminary investigations of the amounts of heat removed from the electrodes by cooling water are presented and evaluated as a function of the power input to the system. Measurements were made of heat generated at the cathode and anode during sputtering in atmospheres of oxygen, argon, and mixtures of oxygen plus argon. Results of these measurements indicate that oxidation occurs almost entirely at surfaces where the film is deposited instead of at the cathode.

The feasibility of preparation and nondestructive analysts of thin glass films in the system of lead and tellurium oxides has been shown by these studies. It is conceivable that the films may be useful as insulators, dielectrics, and protective coatings.

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