The growth of oxygen vacancy controlled HfxTi1-xO2 layers deposited by gas injection magnetron sputtering techniqueShow others and affiliations
2025 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 700, article id 163210Article in journal (Refereed) Published
Abstract [en]
HfxTi1-xO2 layers (0.3 <= x <= 0.86) were grown by the Gas Injection Magnetron Sputtering (GIMS) technique. Binary Hf-Ti targets with the Hf/Ti atomic ratios of 1/4, 2/3, 3/2, and 4/1, fabricated using plasma surface sintering, were used for reactive sputtering in the fixed Ar/O-2 gas mixture. The initial growth of the GIMS-deposited HfxTi1-xO2 layers was characterized by an amorphous structure, which crystallized along the oxide layer growth direction when the Hf content was sufficient (x > 0.74). The lattice structure of oxide layers with x <= 0.86 exhibited monoclinic crystallization, which is characteristic of HfO2. However, when x = 0.74, a highly non-equilibrium mixture of monoclinic and rhombohedral HfO2 phases was formed. The XPS study showed that these layers' Hf-O-x and Ti-O-x bonds were locally O-deficient, indicating that oxygen vacancies control the formation of HfxTi1-xO2. The optical properties of the fabricated layers also changed markedly when the chemical composition was modified. For example, an increase in the Hf fraction reduced the extinction coefficient from 1 to 0.2 at 250 nm and the refractive index from 2.45 to 2.3 in the visible range. We indicated that oxygen vacancies create the mid-band states, shifting the absorption towards lower energies. As the x value was increased from 0.30 to 0.86, the corresponding absorption shifted from 3.20 to 2.55 eV. In addition, Hf-rich layers revealed a significant increase in hardness and reduced Young's modulus by 73 % and 30 %, respectively. All layers were also hydrophobic.
Place, publisher, year, edition, pages
ELSEVIER , 2025. Vol. 700, article id 163210
Keywords [en]
Magnetron sputtering; Gas Injection Magnetron Sputtering; TiO2 layers; HfO(2 )layers; XPS; Optical properties
National Category
Other Chemistry Topics
Identifiers
URN: urn:nbn:se:liu:diva-213268DOI: 10.1016/j.apsusc.2025.163210ISI: 001470586600001Scopus ID: 2-s2.0-105002281278OAI: oai:DiVA.org:liu-213268DiVA, id: diva2:1954831
Note
Funding Agencies|Warsaw University of Technology's Scientific Disciplines Councils [504/04931/1090/43.082401]; National Agency for Academic Exchange [BPN/BEK/2021/1/00366/U/00001]; Warsaw University of Technology in Excellence Initiative: Research University, Mobility program [CPR-IDUB/21/Z09/2024]
2025-04-282025-04-282025-04-28