Silicon heterojunctions

Author: Pettersson, Per-Olov

Year: 1996

Degree: Dissertation (Ph.D.)

Advisor: McGill, Thomas C.

Committee Member: Unknown, Unknown

Option: Applied Physics

DOI: 10.7907/pvjr-8w50

Abstract

The three topics presented in this thesis all concern silicon heterojunction growth and device applications. We developed growth techniques for two relatively immature material systems, silicon/calciumfluoride (Si/CaF2) and silicon/silicon-carbon (Si/Si1-yCy), and fabricated devices which take the mature silicon/silicon dioxides (Si/SiO2) material system to new limits in terms of oxide thickness.

We applied novel growth techniques in the undeveloped material systems with the ultimate goal of producing device quality material suitable for quantum device fabrication. In the Si/CaF2 material system, we used a new technique known as Electron Beam Assisted Molecular Beam Epitaxy to improve the morphology of silicon grown on calciumfluoride. The result was a decrease in roughness of the silicon overlayer. In the silicon/silicon-carbon material system, we employed Surfactant Assisted Molecular Beam Epitaxy to grow smooth high carbon content silicon-carbon on silicon. Here, the result was a greatly improved surface morhology and the technique looks promising for applications requiring high carbon concentrations.

In the mature and extremely important (from a technological and commercial point of view) Si/SiO2 material system, we fabricated Metal Insulator Semiconductor Switches devices in a study of the dependence of the I/V curve on the insulator thickness. While the primary objective of this study was to optimize the I/V curve, we learned that this material system is not very well understood, neither from a theoretical nor experimental standpoint, when the oxide is extremely thin.

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