UV/ozone induced oxidation of silicon(1-x) germanium(x) alloys and thermal desorption of the oxide film

This research project examines the fundamental issues associated with UV/ozone induced oxidation of Si$\sb{\rm 1-x}$Ge$\sb{\rm x}$ alloys and thermal desorption of the oxide film. A low temperature technique has been demonstrated for cleaning Ge wafer surfaces for the growth of high quality epitaxial films. Using x-ray photoelectron spectroscopy (XPS) and other techniques, it is shown that 30 min exposures of a degreased and deionized-water-rinsed Ge wafer to ultraviolet (UV) emission from a Hg lamp in laboratory air is sufficient to remove C contamination and form a non-permeable passive amorphous GeO$\sb2$ layer with a thickness of $\sim$3 nm. Subsequent annealing in ultrahigh vacuum (UHV) at $>$400$\sp\circ$C resulted in desorption of the oxide layer leaving behind a clean well-ordered Ge surface with no C or O impurities. Si$\sb{\rm 1-x}$Ge$\sb{\rm x}$ alloy films with different Ge fractions, grown epitaxially by molecular beam epitaxy (MBE) on Si (111) substrates, were oxidized by exposure to UV-ozone for different times. This resulted in the growth of a uniform oxide film containing both Si and Ge in the +4 state. The oxide thickness initially increased rapidly but reached a saturation value. This varied from 1.3 to 3 nm for Ge fractions of 0 to 100% in the semiconductor alloy. This behavior is consistent with the existence of a space charge region resulting from photo-excitation of electrons from the SiGe valence band into the oxide. The photoelectrons assist in ionizing surface oxygen, a critical step in the oxidation reaction.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Materials Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Agarwal, Avinash Kumar

Contributors dc:contributor

• Rockett, Angus A.

• Engineering, Materials Science

Statement dc:rights

• Copyright 1994 Agarwal, Avinash Kumar

Language dc:language

eng

Identifier

AAI9512278
(UMI)AAI9512278

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21757