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Theodosia Gougousi

Theodosia Gougousi
Contact Information

gougousi@umbc.edu 
410-455-6874
Physics, Rm 317

Research Pages

Title

Professor

Education

Ph.D. Physics – University of Pittsburgh, 1996
M.Sc. Physics – University of Pittsburgh, 1993
B.S. Physics – Aristotle University of Thessaloniki, GREECE, 1990

Previous Experience

Dr. Gougousi joined UMBC after postdoctoral appointments at North Carolina State University and the University of Maryland College Park.

Professional Interests

My research interests lie in the area of nanostructures materials, thin films and interfaces. As the critical dimension of nanodevices reaches the atomic scale, interface phenomena become critical because they define the operation of nanodevices. As a result, understanding the atomic level mechanisms that define the formation of heterogeneous interfaces is a critical challenge in advanced materials systems. One of the research areas we are focusing in my lab is studies of the interface properties of metal oxide films on semiconductors. These materials systems have important technological applications and are under extensive investigation.  For this work we use atomic layer deposition that permits atomic level of the film thickness and morphology and achieves very smooth, uniform, conformal films even on very high aspect ratio structures. Although ALD is usually thought of as a modified version of Chemical Vapor Deposition (CVD), it exhibits some unique features:  film formation is achieved by alternating exposure of a surface to the vapor of two chemical reagents that react in a complementary, self-limiting manner. Complementary means that each of the two reagents must prepare the surface for reaction with the other chemical so the process is cyclical. The dependence of the deposition on favorable surface chemistry can be exploited to achieve selective deposition that is the basis of the so-called “bottom-up” approaches for the formation of nanostructures.

Another are of interest for our group is the use of solvation energy instead of thermal energy to provide a viable alternative for the deposition of thin films in cases where low temperature processing is required.  A special category of solvents is supercritical fluids, which are substances that have been heated and compressed beyond their critical point. In that state they exhibit very intriguing properties  such as liquid-like density that is a tunable function of temperature and pressure,  gas-like diffusivity, low viscosity, and zero surface tension that allows diffusion in high aspect ratio trenches and microporous structures. Of all supercritical fluids, supercritical carbon dioxide (sc CO2) has attracted the most interest because it has an easily accessible critical point of 1070 psi and 31.0 °C. We have demonstrated so far the deposition of several binary metal oxide films in supercritical carbon dioxide at temperatures around 100°C. This low process temperature permits deposition on flexible templates that can be used to form nanostructured materials such as nanotubes and nanowires.

Our research has attracted support from NSF and the ACS Petroleum Research Fund.

Selected Publications

Alex J. Henegar, and Theodosia Gougousi; Native oxide transport and removal during the atomic layer deposition of Ta2O5 on InAs (100) surfaces J. Vac. Sci. Technol. A 34 (3), 031101 (2016).

Alex J. Henegar, Andrew J. Cook, Phillip Dang, and Theodosia Gougousi; Native Oxide Transport and Removal During the Atomic Layer Deposition of TiO2 Films on GaAs (100) Surfaces ACS applied materials & interfaces 8 (3), 1667–1675 (2016).

Liwang Ye and Theodosia Gougousi; Diffusion and interface evolution during the atomic layer deposition of TiO2 on GaAs(100) and InAs(100) surfaces J. Vac. Sci. Technol. A34, 01A105 (2016).

Pietro Strobbia, Alex Henegar, Theodosia Gougousi, and Brian M. Cullum; Layered Gold and Titanium Dioxide Substrates for Improved Surface Enhanced Raman Spectroscopic Sensing Applied Spectroscopy, 0003702816647964 (2016).

Alex J. Henegar and Theodosia Gougousi; Stability and Surface Reactivity of Anatase TiO2 Films  ECS Journal of Solid State Science and Technology, 4 (8) P298-P304 (2015).

Liwang Ye and Theodosia Gougousi In situ infrared spectroscopy study of the interface self-cleaning during the atomic layer deposition of HfO2 on GaAs(100) surfaces Applied Physics Letters 105, 121604 (2014).

Liwang Ye and Theodosia Gougousi Indium Diffusion and Native Oxide Removal during the Atomic Layer Deposition (ALD) of TiO2 Films on InAs(100) Surface ACS Appl. Mater. Interfaces 5(16), 8081–8087, (2013)

Theodosia Gougousi and Liwang Ye; Interface Between Atomic Layer Deposition Ta2O5 Films and GaAs(100) Surfaces J. Phys. Chem. C, 116 (16), 8924–8931 (2012)

Images showing the dissolution of metal organic precursors in supercritical carbon dioxide.Gougousi 1 Gougousi 2 Gougousi 3 Gougousi 4

Gougousi 5

Notice that in the first picture the cell is white and a heap of solid is seen and in the final image it has a yellowish color. The transition to the supercritical state is marked by the cloudiness in the middle image.