Title

Studies of the initial stage of silicon carbide growth on silicon

Semester

Spring

Date of Graduation

2001

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

Charter D. Stinespring.

Abstract

The lack of understanding concerning the initial stage of silicon carbide (SiC) growth on silicon (Si) substrates gives rise to heated debates on the growth mechanisms, the characteristics of the "optimal" initial layers, and the processing parameters necessary to produce high-quality cubic or beta silicon carbide (beta-SiC) on these initial layers. If the potential of beta-SiC as a semiconductor for electronic devices is to be realized, the growth of the initial layers (i.e. the initial stage of growth) must be understood and then controlled.;This dissertation presents results from the comparison of the initial stages of beta-SiC growth by gas source molecular beam epitaxy (GSMBE) on Si(100) substrates after 3 different substrate preparation procedures: argon ion etch and anneal, Fenner etch, and Fenner etch and anneal. GSMBE film growth conditions included 3 gas phase growth precursors (ethylene, methyl radicals, and trimethylsilane) at high and low-flux conditions and substrates temperatures of 700°C and 800°C. Films grown in these studies were characterized with Auger electron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy.;It is reported that the hydrogen terminated Si(100) 1 x 1 (unreconstructed or bulk-like) surface, produced by the Fenner etch procedure, enables the formation of a more-effective silicon diffusion barrier in the earlier stages of growth than the other two surface treatments. The effect of the silicon surface treatment overshadows the influence of growth species identity and flux as well as substrate temperature under many conditions. Because the reduction of silicon surface activity is a key to controlling SiC film growth on Si substrates, the Fenner Etch surface is a promising starting point for the growth of high-quality films. The film characteristics observed for the different substrate surfaces and controlled experimental parameters allowed a study of initial surface reactions from which growth mechanisms could be postulated.

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