See Thesis assignments

Tailoring HfO2 : unraveling the critical parameters for structure control

Tailoring HfO2 : unraveling the critical parameters for structure control

Contact: Cristiane Stilhano Vilas Boas (c.r.stilhanovilasboas@utwente.nl)

In this project, the student will be challenged into exploring and verifying the main synthesis parameters that influence the final structure of nm-thick HfO2 films.

There is tremendous interest in the science and applications of ultrathin oxide films. However, an overarching problem of central importance is the synthesis of these films with desired properties. One way to control and optimize the chemical and physical properties of oxide films is by tailoring the oxide microstructure. However, the technological potential for this control is still limited by a lack of fundamental and comprehensive knowledge of the kinetics and thermodynamics of oxide growth. This lack of knowledge comes from the complexity of the oxidation process, which depends on a series of parameters, such as: temperature (T), partial pressure of oxygen (pO2), roughness and crystallographic orientation of the substrate used for oxide growth.

To explore the mentioned challenge, the student will work in a state-of-the-art nanoscience lab, being in contact with ultra-high vacuum deposition techniques (e.g. magnetron sputtering) and high-resolution characterization methods (such as X-ray photoelectron spectroscopy, ellipsometry and X-ray diffractometry). Furthermore, the student will be part of a team of physics and nanotechnology experts, who engage in regular fruitful scientific discussions. 

We welcome a student with high interest in experimental physics and curiosity to explore the theory behind the observed many interesting aspects related to thin-film science.

The material Hafnium oxide (HfO2) is a wide bandgap (5.3–5.7 eV), chemically inert, and optically transparent dielectric. It has a high refractive index (n=2.04) and a high dielectric constant. Because of these merits, it has found applications in optical coatings, DRAM capacitors, and fabrication of sub 0.1 μm complementary metal oxide semiconductor devices. The chemical and physical properties of the oxide films needed for each of the mentioned applications will depend on their microstructure. Therefore, by understanding how to tailor its crystal structure, you will contribute to the knowledge needed for the fabrication of important technological systems.