Sulfurizing and selenizing metal films in ultra-high vacuum by hydride gas kinetic control

Abstract

Molecular beam epitaxy (MBE) is an important, well-established method for creation of thin films. The addition of gaseous sources of hydrogen sulfide and hydrogen selenide is not currently a well-documented or common modification to such systems. While the thermodynamics of using such sources for the production of various chalcogenide thin films are favorable, the actual results thus far do not demonstrate the desired outcome. This indicates that the kinetics of the desired reactions are inhibiting the process. Compared to oxygen, reactions involving sulfur and selenium are slow. In order to ensure that the hydride gases have the opportunity to react as desired, it is necessary to keep the system free of oxygen and to maximize the collisions of gas molecules with the substrate. The first requirement should be achieved simply by using MBE for the process. The second requirement is not provided for in a typical MBE system. Thus, modifications are necessary to increase the reaction rate of the gases, namely by extending the source lines to be closer to the substrate. This thesis addresses the design process for tubing inserts in an existing MBE system.