Синтез та оцінка композитного матеріалу з наночастинками

Об’єкт дослідження – мінералізовані тканини. Предмет досліджень – зміни метаболізму мінералізованих тканин при використанні остеопластичних матеріалів з структурно-інтегрованими наночасточками срібла та міді. Мета роботи – визначити особливості метаболізму мінералізованих тканин при використанні остеопластичних матеріалів з наночасточками міді та срібла

Computer graphics technologies in temperature space research of industrial building interiors

Taking into account the multi parameter character of the investigated process, the means of multidimensional applied geometry for constructing a graphic model of the temperature space of an industrial building interior wasproposed. Constructed with the help of computer technologies, the models allow, on thebasis of the physical analysis of a particular regime, the performance of the proposedtechnical means for increasing the efficiency of the system of infra-red heating and ventilation in industrial premises of various uses to be evaluated. The aim of the study is to offer universal geometric shaped models of processes of thermal and ventilation modes for studying the temperature space of an industrial building interior

Internal Photoemission Metrology of Inhomogeneous Interface Barriers

Interfaces of heterogeneous solids, ranging from polycrystalline materials to composites, are frequently encountered in nanotechnology. Electron transport in these materials and across their interfaces critically depends on the energy barriers electrons encounter on their way. Because of electrode structural heterogeneity, the barriers may exhibit significant spatial variations resulting in a broad distribution of barrier heights and built-in potentials. Quantification of the distributed interface barriers represents a formidable experimental challenge since direct association of interface properties with those of an outer free surface is generally inaccurate. Here we present a methodology enabling quantification of electron barriers at interfaces of semiconductors and metals with insulators using the electric field-dependent internal photoemission (IPE) of electrons. It is shown that practically relevant interfaces may contain “patches” with differences in barrier height (or the effective work function) of up to 1 eV, which makes the electrode heterogeneity a crucial factor in designing electron devices suitable for low-voltage operation.This work was supported by the Fonds Wetenschappelijk Onderzoek Vlaanderen (Project G.OCO5.13) and by the Internal University Fund project C14/16/061.status: publishe

Metal- and oxide-related hydrogen-induced dipoles at the Pt/HfO2 interface

Such technologically abundant agent as hydrogen has a strong effect on the metal/oxide interface energy barrier. Internal photoemission analysis of electron barrier height variations at Pt/HfO2 interfaces caused by annealing in hydrogen reveals the formation of a significant (≥0.4 eV) electrostatic dipole layer. The orientation of the H-induced dipole appears to be sensitive to the growth conditions and treatments, e.g., Hf precursor used in the atomic layer deposition (ALD) process: In the case of the HfCl4 precursor, annealing in H2 leads to barrier lowering, whereas the barrier becomes higher in samples grown by using tetrakis(dimethylamido)hafnium. These findings indicate that hydrogen may form dipoles of opposite orientation through two different mechanisms: The positive dipole is caused by H interaction with the metal surface, which can also be found at interfaces of Pt with other oxides such as SiO2 and Al2O3. By contrast, the sensitivity of the negative dipole formation to the HfO2 ALD chemistry suggests it to be related to a negatively charged bonded state of hydrogen in the near-interface oxide.Moreover, the formation of positive dipole is also observed after high temperature anneal in nitrogen suggesting the contribution of additional mechanisms of dipole formation.The work at KU Leuven was supported by Fonds Wetenschappelijk Onderzoek – Vlaanderen (Project G.0C05.13) and by the Internal Fund project C14/16/061.status: publishe

Hydrogen induced dipole at the Pt/oxide interface in MOS devices

Thanks to its good thermal stability, including resistance to oxidation, platinum (Pt) is widely used in prototyping a wide spectrum of electron devices ranging from metaloxide- semiconductor (MOS) transistors to resistive switching memory cells. In this work, the energy barriers for electrons between the Fermi level of Pt and the conduction band of several oxide insulators (SiO2, Al2 O3, HfO2, Hf0.8Al0.2Ox, Sr0.53Ti0.47O3) were determined by using internal photoemission of electrons. By combining this barrier value with the electron affinity of the particular oxide, the effective work function (EWF) of Pt was determined for different interfaces. As studied over the reference Pt/oxide/Si stacks de-gassed in high vacuum at 400 8C, the EWF of Pt is found to differ significantly from the accepted vacuum WF value of 5.6 eV. The EWF is equal to 5.2 eV at the Pt/Al2O3 interface, 5.1 eV at Pt/HfO2, 5.3 eV at Pt/Hf0.8Al0.2Ox, 4.8 eV at Pt/SiO2, and 5.8 eV at the Pt/Sr0.53Ti0.47O3 interface indicating the presence of a polarization layer of which the contribution to the EWF depends on the oxide composition. Furthermore, annealing in H2 at 400 8C reduces the Pt EWF by 0.5 eV at all interfaces except for the Pt/Sr0.53Ti0.47O3 one. This observation indicates the formation of an additional H-related dipole at the Pt/oxide interfaces and suggests that the vacuum WF of Pt cannot be used as the value relevant for the MOS properties.status: publishe

Analysis of Oxygen and Nitrogen Redistribution at Interfaces of HfO2 with Laminate TiN/TiAl/TiN Electrodes

status: publishe

Ultra-thin ZrO2/SrO/ZrO2 insulating stacks for future dynamic random access memory capacitor applications

Aiming for improvement of the ZrO2-based insulator properties as compared to the state-of-the-art ZrO2/Al2O3/ZrO2 stacks beyond 20 nm dynamic random access memory (DRAM) technology applications, ultra-thin (5 nm) ZrO2/SrO/ZrO2 stacks with TiN electrodes deposited by physical vapor deposition are addressed. By replacing the Al2O3 interlayer with SrO, the effective dielectric permittivity of the stack can be increased as indicated by electrical analysis. At the same time, no degradation of the insulating properties of the SrO-containing stacks and minor changes in the reliability, compared to an Al2O3 interlayer, are found. These results are indicating the possibility of further reducing the effective oxide thickness of the ZrO2-based stacks to come close to 0.5 nm for future DRAM capacitors.status: publishe

Mechanisms of TiN Effective Workfunction Tuning at Interfaces with HfO2 and SiO2

status: publishe

Low leakage ZrO2 based capacitors for sub 20 nm DRAM technology nodes

During DRAM capacitor scaling a lot of effort was spent searching for new material stacks to overcome the scaling limitations of the current material stack, such as leakage and sufficient capacitance. In this study, very promising results for a SrTiO3 based capacitor with a record low capacitance equivalent thickness value of 0.2 nm at target leakage current are presented. Due to the material properties of SrTiO3 films (high vacancy concentration and low band gap), which are leading to an increased leakage current, a physical thickness of at least 8 nm is required at target leakage specifications. However, this physical thickness would not fit into an 18 nm DRAM structure. Therefore, two different new approaches to develop a new ZrO2 based DRAM capacitor stack by changing the inter-layer material from Al2O3 to SrO, and the exchange of the top electrode material from TiN to Pt are presented. A combination of these two approaches leads to a capacitance equivalent thickness value of 0.47 nm. Most importantly, the physical thickness of < 5 nm for the dielectric stack is in accordance with the target specifications. Detailed evaluations of the leakage current characteristics lead to a capacitor model which allows the prediction of the electrical behavior with thickness scaling.status: publishe