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Freie Universität Berlin

1. Mauch, Irene. Ballistic Electron Emission Microscopy (BEEM) of Au/Pr2O3/Si structures.

Degree: 2007, Freie Universität Berlin

This thesis describes Ballistic Electron Emission Microscopy (BEEM) measurements of Au/Si(111) and Au/Pr2O3 /Si(111) structures. This technique is based on Scanning Tunnelling Microscopy (STM). It measures the ballistic transport of hot electrons through parts of the sample and across an interface, which provides a potential barrier. One part of this work was to modify the BEEM apparatus and to implement a lock in method, which modulates the tunnel current with a small frequency. In this way it is possible to study samples with very low resistance (as low as 30 kΩ), which widely enlarges the number of samples which are appropriate for BEEM measurement at room temperature. Both types of samples studied in this thesis had low resistance and were therefore studied using the lock in method. For the classical BEEM system Au/Si(111), we observed a pronounced dependence of the sample resistance of Au/Si(111)-7x7 on the preparation temperature. We developed a model for the resistance of thermal prepared Au/Si(111)-7x7 samples. The model identifies that the low resistance is due to the surface conductivity of the reconstructed silicon surface. If the surface is prepared at a lower temperature (but still high enough that the surface is cleaned and the silicon dioxide desorbed) rough areas remain on the surface, which reduce the surface conductivity. For BEEM measurements flat areas of the sample surface are selected. The low temperature prepared samples we were able to obtain BEEM spectra as well as images at room temperature using the lock in method. The sesquioxide of praseodymium (Pr2O3) is currently discussed as a possible candidate for a gate oxide in semiconductor devices, since it has some of the required material properties such as a high dielectric constant, low leakage current and epitaxial growth on Si(100). We have for the first time performed BEEM measurement of praseodymium oxide. Despite a low resistance of the structures we were able to obtain BEEM-spectra and BEEM-images of Au/Pr2O3/Si(111) structures using a submonolayer thick Pr2O3 film at the Au/Si interface. In the BEEM images the interface is directly visualized. The structure of the submonolayer Pr2O3 film, i.e. the size and form of the islands, can be studied. From the measured BEEM spectra, we determined the conduction band offset between silicon and praseodymium oxide. Advisors/Committee Members: n (gender), Prof. Dr. Dr. h.c. Günter Kaindl (firstReferee), Prof. Dr. Paul Fumagalli (furtherReferee).

Subjects/Keywords: ballistic electron emission microscopy; praseodymium oxide; metal oxide semiconductor structures; hot electron transport; conduction band offset; 68.37.-d; 73.40.-c; 73h.40.Qv; 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik

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APA (6th Edition):

Mauch, I. (2007). Ballistic Electron Emission Microscopy (BEEM) of Au/Pr2O3/Si structures. (Thesis). Freie Universität Berlin. Retrieved from http://dx.doi.org/10.17169/refubium-4262

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Mauch, Irene. “Ballistic Electron Emission Microscopy (BEEM) of Au/Pr2O3/Si structures.” 2007. Thesis, Freie Universität Berlin. Accessed August 05, 2020. http://dx.doi.org/10.17169/refubium-4262.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Mauch, Irene. “Ballistic Electron Emission Microscopy (BEEM) of Au/Pr2O3/Si structures.” 2007. Web. 05 Aug 2020.

Vancouver:

Mauch I. Ballistic Electron Emission Microscopy (BEEM) of Au/Pr2O3/Si structures. [Internet] [Thesis]. Freie Universität Berlin; 2007. [cited 2020 Aug 05]. Available from: http://dx.doi.org/10.17169/refubium-4262.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mauch I. Ballistic Electron Emission Microscopy (BEEM) of Au/Pr2O3/Si structures. [Thesis]. Freie Universität Berlin; 2007. Available from: http://dx.doi.org/10.17169/refubium-4262

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


North Carolina State University

2. Jur, Jesse Stephen. Lanthanide-based Oxides and Silicates for High-K Gate Dielectric Applications.

Degree: PhD, Materials Science and Engineering, 2007, North Carolina State University

The ability to improve performance of the high-end metal oxide semiconductor field effect transistor (MOSFET) is highly reliant on the dimensional scaling of such a device. In scaling, a decrease in dielectric thickness results in high leakage current between the electrode and the substrate by way of direct tunneling through the gate dielectric. Observation of a high leakage current when the standard gate dielectric, SiO2, is decreased below a thickness of 1.5 nm requires engineering of a replacement dielectric that is much more scalable. This high- dielectric allows for a physically thicker oxide, reducing leakage current. Integration of select lanthanide-based oxides and silicates, in particular lanthanum oxide and silicate, into MOS gate stack devices is examined. The quality of the high-K dielectrics is monitored electrically to determine properties such as equivalent oxide thickness, leakage current density and defect densities. In addition, analytical characterization of the dielectric and the gate stack is provided to examine the materialistic significance to the change of the electrical properties of the devices. It is shown that optimization of low-temperature processing can result in MOS devices with an equivalent oxide thickness (EOT) as low 5 Å and a leakage current density of 5.0 A⁄cm2. High-temperature processing, consistent with a MOSFET source-drain activation anneal, yields MOS devices with an EOT as low as 1.1 nm after optimization of the TaN/W electrode properties. The decrease in the device effective work function (phi_M,eff) observed in these samples is examined in detail. First, as a La2O3 capping layer on HfSiO(N), the shift yields ideal-phi_M,eff values for nMOSFET deices (4.0 eV) that were previously inaccessible. Other lanthanide oxides (Dy, Ho and Yb) used as capping layers show similar effects. It is also shown that tuning of phi_M,eff can be realized by controlling the extent of lanthanide-silicate formation. This research, conducted in conjunction with SEMATECH and the SRC, represents a significant technological advancement in realizing 45 and sub-45 nm MOSFET device nodes. Advisors/Committee Members: Angus Kingon, Committee Chair (advisor), Gregory Parsons, Committee Member (advisor), Jon-Paul Maria, Committee Member (advisor), Mark Johnson, Committee Member (advisor).

Subjects/Keywords: dc magnetron sputtering; physical vapor deposition; tungsten oxide; tungsten; W; tantalum nitride; TaN; lanthanum; lanthanum oxide; La; La2O3; La2SiO5; lanthanum silicate; La2Si2O7; Ho; holmium; holmium oxide; cation diffusion; back-side SIMS; secondary ion mass spectroscopy; SIMS; XRD; x-ray diffraction; molecular beam deposition; PMA; XPS; x-ray photoemission spectroscopy; post metallization anneal; RCA; chemical oxide; metal oxide semiconductor field effect transistor; MBE; silica; SiO2; interfacial layer; gate dielectric; dielectric; silicate; oxide; high-kappa; EOT; equivalent oxide thickness; high-k; band diagram; valance band offset; conduction band offset; band gap energy; effective work function; work function; voltage shift; threshold voltage; flat band voltage; leakage current; capacitance; mobility; electronic materials; scaling; Moore?s Law; MIS; MOS; MOSFET; high resolution transmission electron microscopy; HRTEM; RTA; rapid thermal anneal; PVD; tantalum; Ta; gate electrode; metal electrode; hafnium silicate; hafnium oxide; hafnium; ytterbium; ytterbium oxide; Yb; dysprosium oxide; dysprosium; Dy; E-beam evaporation; thermal evaporation; forming gas anneal; ozone; ammonia anneal; FGA

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Jur, J. S. (2007). Lanthanide-based Oxides and Silicates for High-K Gate Dielectric Applications. (Doctoral Dissertation). North Carolina State University. Retrieved from http://www.lib.ncsu.edu/resolver/1840.16/5447

Chicago Manual of Style (16th Edition):

Jur, Jesse Stephen. “Lanthanide-based Oxides and Silicates for High-K Gate Dielectric Applications.” 2007. Doctoral Dissertation, North Carolina State University. Accessed August 05, 2020. http://www.lib.ncsu.edu/resolver/1840.16/5447.

MLA Handbook (7th Edition):

Jur, Jesse Stephen. “Lanthanide-based Oxides and Silicates for High-K Gate Dielectric Applications.” 2007. Web. 05 Aug 2020.

Vancouver:

Jur JS. Lanthanide-based Oxides and Silicates for High-K Gate Dielectric Applications. [Internet] [Doctoral dissertation]. North Carolina State University; 2007. [cited 2020 Aug 05]. Available from: http://www.lib.ncsu.edu/resolver/1840.16/5447.

Council of Science Editors:

Jur JS. Lanthanide-based Oxides and Silicates for High-K Gate Dielectric Applications. [Doctoral Dissertation]. North Carolina State University; 2007. Available from: http://www.lib.ncsu.edu/resolver/1840.16/5447

.