arXiv subjects

Zsolt Tokei

Publications and source records attributed to Zsolt Tokei.

5 recordsLinked to original sources

arXiv2024

Sub-40mV Sigma-VTH IGZO nFETs in 300mm Fab

Back and double gate IGZO nFETs have been demonstrated down to 120nm and 70nm respectively leveraging 300mm fab processing. While the passivation of oxygen vacancies in IGZO is challenging with an integration of front side gate, a scaled back gated flow has been optimized by multiplying design of experiments around contacts and material engineering. We then successfully demonstrated sub-40mV $σ$(VTH_ON) in scaled IGZO nFETs. Regarding the performance and the VTH_ON control, a new IGZO phase is also reported. A model of dopants location is proposed to better explain the experimental results reported in literature.

cond-mat.mtrl-sci↗

arXiv2020

Temperature-Dependent Resistivity of Alternative Metal Thin Films

The temperature coefficients of the resistivity (TCR) of Cu, Ru, Co, Ir, and W thin films have been investigated as a function of film thickness below 10 nm. Ru, Co, and Ir show bulk-like TCR values that are rather independent of the thickness whereas the TCR of Cu increases strongly with decreasing thickness. Thin W films show negative TCR values, which can be linked to high disorder. The results are qualitatively consistent with a temperature-dependent semiclassical thin film resistivity model that takes into account phonon, surface, and grain boundary scattering.

cond-mat.mtrl-sci↗

arXiv2017

Comprehensive Modeling of Graphene Resistivity

Since the first graphene layer was fabricated in the early 2000's, graphene properties have been studied extensively both experimentally and theoretically. However, when comparing the many resistivity models reported in literature, several discrepancies can be found, as well as a number of inconsistencies between formulas. In this paper, we revise the main scattering mechanisms in graphene, based on theory and goodness of fit to in-house experimental data. In particular, a step-by-step evaluation of the interaction between electrons and optical phonons is carried out, where we demonstrate that the process of optical phonon emission scattering is completely suppressed for all low-field applications and all temperatures in the range of interest, as opposed to what is often reported in literature. Finally, we identify the best scattering models based on the goodness of fit to experimental data.

physics.app-ph↗

arXiv2017

Thickness dependence of the resistivity of Platinum group metal thin films

We report on the thin film resistivity of several platinum-group metals (Ru, Pd, Ir, Pt). Platinum-group thin films show comparable or lower resistivities than Cu for film thicknesses below about 5\,nm due to a weaker thickness dependence of the resistivity. Based on experimentally determined mean linear distances between grain boundaries as well as ab initio calculations of the electron mean free path, the data for Ru, Ir, and Cu were modeled within the semiclassical Mayadas--Shatzkes model [Phys. Rev. B 1, 1382 (1970)] to assess the combined contributions of surface and grain boundary scattering to the resistivity. For Ru, the modeling results indicated that surface scattering was strongly dependent on the surrounding material with nearly specular scattering at interfaces with SiO2 or air but with diffuse scattering at interfaces with TaN. The dependence of the thin film resistivity on the mean free path is also discussed within the Mayadas--Shatzkes model in consideration of the experimental findings.

cond-mat.mtrl-sci↗

arXiv2015

Electron relaxation times and resistivity in metallic nanowires due to tilted grain boundary planes

We calculate the resistivity contribution of tilted grain boundaries with varying parameters in sub-10nm diameter metallic nanowires. The results have been obtained with the Boltzmann transport equation and Fermi's golden rule, retrieving correct state-dependent relaxation times. The standard approximation schemes for the relaxation times are shown to fail when grain boundary tilt is considered. Grain boundaries tilted under the same angle or randomly tilted induce a resistivity decrease.

cond-mat.mes-hall↗