Spectroscopic Study of Hafnium Silicate Alloys prepared by RPECVD: Comparisons between Conduction/Valence Band Offset Energies and Optical Band Gaps

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dc.contributor.advisor Gerald Lucovsky, Committee Chair en_US
dc.contributor.advisor Carlton Osburn, Committee Member en_US
dc.contributor.advisor Gerd Duscher, Committee Member en_US
dc.contributor.advisor Klaus Bachmann, Committee Member en_US
dc.contributor.author Hong, Joon Goo en_US
dc.date.accessioned 2010-04-02T18:25:21Z
dc.date.available 2010-04-02T18:25:21Z
dc.date.issued 2003-12-31 en_US
dc.identifier.other etd-12302003-225708 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/2978
dc.description.abstract Aggressive scaling of devices has continued to improve MOSFET transistor performance. As lateral device dimensions continue to decrease, gate oxide thickness must be scaled down. As one of the promising high k gate oxide material, HfO₂ and its silicates were investigated to understand their direct tunneling behavior by studying conduction and valence band offset energies with spectroscopy and electrical characterization. Local bonding change of remote plasma deposited (HfO₂)[subscript x](SiO[subscript 8322;)[subscript 1-x] alloys were characterized by Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) as a function of alloy composition, x. Two different precursors with Hf Nitrato and Hf-tert=butoxide were tested to have amorphous deposition. Film composition was determined off-line by Rutherford backscattering spectroscopy (RBS) and these results were calibrated with on-line AES. As deposited Hf-silicate alloys were characterized by off-line XPS and AES for their chemical shifts interpreting with a partial charge transfer model as well as coordination changes.Sigmoidal dependence of valence band offse energies was observed. Hf 5d state is fixed at the bottom of the conduction band and located at 1.3 ± 0.2 eV above the top of the Si conduction band as a conduction band offset by x-ray absorption spectroscopy (XAS). Optical band gap energy changes were observed with vacuum ultra violet spectroscopic ellipsometry (VUVSE) to verify compositional dependence of conduction and valence band offset energy changes. 1 nm EOT normalized tunneling current with Wentzel-Kramer-Brillouin (WKB) simulation based on the band offset study and Franz two band model showed the minimum at the intermediate composition matching with the experimental data. Non-linear trend in tunneling current was observed because the increases in physical thickness were mitigated by reduction in band offset energies and effective mass for tunneling. C-V curves were compared to each other, and more hysteresis was observed with increasing x. Localized Hf 5d state as a trap site was the reason for hysteresis and its reverse direction with temperature-dependent C-V curves. Temperature-dependent I-V study located Hf 5d state. For the integration issue, nitridation study was performed at the interface, surface and both. Interfacial nitridation gave more effective reduction in EOT. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject RPE-CVD. MOCVD en_US
dc.subject local bond en_US
dc.subject FTIR en_US
dc.subject Poole-Frenkel en_US
dc.subject nitridation en_US
dc.subject temperature dependent CV en_US
dc.subject IV en_US
dc.subject CV en_US
dc.subject electrical property en_US
dc.subject transition metal oxide en_US
dc.subject Optical Band Gap en_US
dc.subject Valence band en_US
dc.subject Conduction band en_US
dc.subject Hafnium Silicate en_US
dc.subject Spectroscopy en_US
dc.subject High k gate oxide en_US
dc.title Spectroscopic Study of Hafnium Silicate Alloys prepared by RPECVD: Comparisons between Conduction/Valence Band Offset Energies and Optical Band Gaps en_US
dc.degree.name PhD en_US
dc.degree.level dissertation en_US
dc.degree.discipline Materials Science and Engineering en_US

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