Hexagonal boron nitride (h-BN) thin films are deposited by plasma enhanced
chemical vapor deposition (PECVD). Effects of heat treatment and source gases on
the structure and physical properties are investigated. Chemical bonding is analyzed
in comparison with the better understood isoelectronic carbon compound, graphite. It
seems that the basic difference between h-BN and graphite arises from the different
electronegativities of boron and nitrogen atoms. Optical absorptions in UV-visible
range for crystalline and amorphous structures are outlined. The expressions used for
the evaluation of mechanical stress induced in thin films are derived. The deposited
films are considered to be turbostratic as they do not exhibit the characteristic optical
absorption spectra of a crystal. A new system, stylus profilometer, is implemented
and installed for thin film thickness and mechanical stress measurements. Hydrogen
atom density within the films, estimated from FTIR spectroscopy, is found to be a
major factor affecting the order and mechanical stress of the films. Heat treatment of
the films reduces the hydrogen content, does not affect the optical gap and slightly
increases the Urbach energy probably due to an increased disorder. Increasing the
nitrogen gas flow rate in the source gas results in more ordered films. The virtual
crystal of these films is detected to be unique. Relative bond concentrations of the constituent elements indicate a ternary boron-oxygen-nitrogen structure. The
physical properties of h-BN such as high resistivity and wide band gap seem suitable
for optoelectronic applications such as gate dielectrics in thin film transistors and
light emitting devices in the blue region.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12608611/index.pdf |
| Date | 01 August 2007 |
| Creators | Anutgan, Mustafa |
| Contributors | Katircioglu, Bayram |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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