PhD Defense: Nimarta Chowdhary
Location
Physics : 401
PhD Defense: Nimarta Chowdhary – Online Event
Date & Time
November 21, 2024, 1:00 pm – 3:00 pm
Description
ADVISOR: Dr. Theodosia Gougousi
TITLE: Investigating the Properties of Transition Metal-Based Thin Films
ABSTRACT: Transition metal-based thin films, including oxides and nitrides, are widely studied due to their diverse properties. Among these materials, transition metal oxides are notable for their wide band gaps, high refractive indices, and transparency in the visible spectrum. Due to their low cost, low toxicity, and natural abundance, efforts are underway to modify these materials for broader applications, such as visible light absorption. However, the production and characterization of these transition metal-based films remains challenging.
This research investigates the growth and properties of transition metal-based films using complementary deposition techniques: atomic layer deposition (ALD) and a physical vapor deposition (PVD) method. ALD thin films of TiO2 and HfO2 were similarly grown with varied deposition parameters, such as temperature and purge times. For each film, the composition, crystal structure, and optical and electrical properties were studied, offering a comprehensive understanding of the temperature and purge effects on the resulting properties. PVD-grown TiOxNy and TiO2 films served as benchmarks for the ALD TiO2 films, providing insights into impurity incorporation. The properties of ALD-grown TiO2 films are shown to be highly dependent on deposition conditions, particularly in the temperature range within the 'ALD window, while the ALD-grown HfO2 films showed stable properties for similar growth conditions. These results highlight that the underlying ALD chemistry and reaction pathways are significantly more complex than is currently understood - growth conditions cannot be generalized for similar materials. By systematically studying thin film properties using this approach, this research establishes pathways for applications in precursor design, photovoltaics, transparent conductive oxides and optoelectronics.
TITLE: Investigating the Properties of Transition Metal-Based Thin Films
ABSTRACT: Transition metal-based thin films, including oxides and nitrides, are widely studied due to their diverse properties. Among these materials, transition metal oxides are notable for their wide band gaps, high refractive indices, and transparency in the visible spectrum. Due to their low cost, low toxicity, and natural abundance, efforts are underway to modify these materials for broader applications, such as visible light absorption. However, the production and characterization of these transition metal-based films remains challenging.
This research investigates the growth and properties of transition metal-based films using complementary deposition techniques: atomic layer deposition (ALD) and a physical vapor deposition (PVD) method. ALD thin films of TiO2 and HfO2 were similarly grown with varied deposition parameters, such as temperature and purge times. For each film, the composition, crystal structure, and optical and electrical properties were studied, offering a comprehensive understanding of the temperature and purge effects on the resulting properties. PVD-grown TiOxNy and TiO2 films served as benchmarks for the ALD TiO2 films, providing insights into impurity incorporation. The properties of ALD-grown TiO2 films are shown to be highly dependent on deposition conditions, particularly in the temperature range within the 'ALD window, while the ALD-grown HfO2 films showed stable properties for similar growth conditions. These results highlight that the underlying ALD chemistry and reaction pathways are significantly more complex than is currently understood - growth conditions cannot be generalized for similar materials. By systematically studying thin film properties using this approach, this research establishes pathways for applications in precursor design, photovoltaics, transparent conductive oxides and optoelectronics.
