Date of Award

12-2006

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Physics

Advisor

Sosolik, Chad

Abstract

A hyperthermal and low energy ion beamline to measure electron-hole pair production due to ion bombardment of Schottky diodes has been modified and assembled.
A brief overview of the instrument is given and the reason for operating the ion beamline in the hyperthermal and low energy regime is discussed. The capabilities of the ion beamline are unique and provide the means to measure quantities that offer insight into various energy exchange mechanisms that occur at surfaces. Combined with the ability to accept Schottky diode samples, the beamline is capable of measuring both charge transfer and electron-hole pair production caused by ion bombardment of the sample.
Details of assembly and modification of the ion beamline as well as theory of operation are discussed. Data verifying the precision of the beamline mass and charge selection processes is provided along with a profile of the ion beam. The beamline has been upgraded to enhance reliability by replacing diffusion pumps with turbomolecular vacuum pumps. Also, the scattering chamber has been outfitted with a load lock system to drastically reduce sample turnaround time, an important feature for the Schottky diode experiments.
The theory of Schottky barriers and Schottky diodes is also discussed. Current and voltage measurements were taken on the Schottky diode device and were used to calculate the Schottky barrier height. Using an Ar high flux ion beam and Na low flux ion beam, preliminary electron hole pair measurements on a Schottky diode are presented. A possible explanation of results is provided by considering an analogue to Schottky diodes, metal-insulator-metal tunnel junctions [1].

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