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Your search keyword '"Michalowski, Pawel Piotr"' showing total 20 results
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20 results on '"Michalowski, Pawel Piotr"'

1. Ultrafast optical properties of stoichiometric and non-stoichiometric refractory metal nitrides TiNx, ZrNx, and HfNx

Author

Judek, Jaroslaw, Dhama, Rakesh, Pianelli, Alessandro, Wrobel, Piotr, Michalowski, Pawel Piotr, Dana, Jayanta, and Caglayan, Humeyra

Subjects
Physics - Optics
Abstract

Refractory metal nitrides have recently gained attention in various fields of modern photonics due to their cheap and robust production technology, silicon-technology compatibility, high thermal and mechanical resistance, and competitive optical characteristics in comparison to typical plasmonic materials like gold and silver. In this work, we demonstrate that by varying the stoichiometry of sputtered nitride films, both static and ultrafast optical responses of refractory metal nitrides can efficiently be controlled. We further prove that the spectral changes in ultrafast transient response are directly related to the position of the epsilon-near-zero region. At the same time, the analysis of the temporal dynamics allows us to identify three time components - the "fast" femtosecond one, the "moderate" picosecond one, and the "slow" at the nanosecond time scale. We also find out that the non-stoichiometry does not significantly decrease the recovery time of the reflectance value. Our results show the strong electron-phonon coupling and reveal the importance of both the electron and lattice temperature-induced changes in the permittivity near the ENZ region and the thermal origin of the long tail in the transient optical response of refractory nitrides.

Published
2023

7. Heavy-hole band splitting observed in mobility spectrum of p-type InAs grown on GaAs substrate

Author

Wrobel, Jaroslaw, Umana-Membreno, Gilberto, Boguski, Jacek, Sztenkiel, Dariusz, Michalowski, Pawel Piotr, Martyniuk, Piotr, Faraone, Lorenzo, Wrobel, Jerzy, and Rogalski, Antoni

Subjects
Condensed Matter - Materials Science
Abstract

High quality berylium doped InAs layer grown by MBE on GaAs substrate has been examined via magnetotransport measurements and high resolution quantitative mobility spectrum analysis in the range from 5 to 300 K and up to 15 T magnetic field. The layer homogenity and dopant concentration has been proofed via HR-SIMS. The results shew four channel conductivity and essential splitting of the most populated holelike channel below 55 K. The multilayer model concluded from the QMSA results has been compared with nextnano simulation., Comment: 13 pages, 7 figures

Published
2019

14. Two-dimensional electron gas at the AlGaN/GaN interface: Layer thickness dependence.

Author

Popok, Vladimir N., Caban, Piotr A., Michalowski, Pawel Piotr, Thorpe, Ryan, Feldman, Leonard C., and Pedersen, Kjeld

Subjects
TWO-dimensional electron gas, ELECTRON gas, KELVIN probe force microscopy, SURFACE potential, THIN films, ELECTRON density
Abstract

In the current paper, the structure and properties of AlGaN/GaN interfaces are studied, explaining the role of AlGaN layer thickness on the two-dimensional electron gas (2DEG) formation. It is found that the generation of a continuous electron gas requires AlGaN films with stable stoichiometry, which can be reached only above a certain critical thickness, ≈6–7 nm in our case (20 at. % Al content). Thinner films are significantly affected by oxidation, which causes composition variations and structural imperfections leading to an inhomogeneity of the polarization field and, as a consequence, of the electron density across the interface. Using Kelvin probe force microscopy, this inhomogeneity can be visualized as variations of the surface potential on the sub-micrometer scale. For heterostructures with layer thickness above the critical value, the surface potential maps become homogeneous, reflecting a weakening influence of the oxidation on the interface electronic properties. The 2DEG formation is confirmed by the Hall measurements for these heterostructures. [ABSTRACT FROM AUTHOR]

Published
2020
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17. Formation of an interface layer between Al1-xSixOy thin films and the Si substrate during rapid thermal annealing

Author

Michalowski, Pawel Piotr, Beyer, Volkhard, Czernohorsky, Malte, Kücher, P., Teichert, Steffen, Jaschke, Gert, Möller, Wolfhard, and Publica

Abstract

Silicon diffusion from the substrate through Al1-xSixOy thin films was investigated by ToF-SIMS depth profiling. Two types of substrate stacks were analyzed: Si wafer with either native oxide or with addnl. silicon nitride layer. The amt. of diffused silicon depends strongly on the type of the substrate. The activation energy for pure alumina was found to be 2.27 ± 0.02 eV and 3.73 ± 0.02 eV for SiO2/Si and Si3N4/SiO2/Si samples, resp. Furthermore it was proved that the activation energy increases with higher concn. of Si for SiO2/Si samples whereas it decreases for Si3N4/SiO2/Si. Detailed anal. of SIMS depth profiles provide satisfactory explanation of this phenomenon: SiO2 has much stronger tendency to react with Al1-xSixOy material forming an interface layer that restrain further diffusion of Si from the substrate. [on SciFinder(R)]

Published
2010

18. Characterization of the diffusium process in Al2O3 thin films based on ToF-SIMS measurements

Author

Michalowski, Pawel Piotr, Czernohorsky, Malte, Beyer, Volkhard, Jaschke, Gert, Teichert, Steffen, and Publica

Abstract

In next generation charge trapping non-volatile memory devices the blocking oxide material (currently SiO2) has to be replaced by a highk dielectric thin film. The appropriate selection of a suitable material from a large variety of potential candidates requires precise analytical characterization techniques. This work focuses on Secondary Ion Mass Spectroscopy (SIMS) of Al2O3 thin films which were fabricated by atomic layer deposition on Si(001) wafers. These samples were treated by rapid thermal annealing in wide range of temperatures (750?1100\'0eC) and gas ambiences (N2, O2, H2). SIMS depth profiles indicate that Si diffuses from the substrate through the alumina during annealing which leads to a segregation of Si on the Al2O3 layer surface. Grain boundary diffusion was identified to have the most significant impact in the diffusion process. Furthermore the activation energy of the diffusion was found to be 0.6 eV/atom and 2.3 eV/atom for amorphous and crystalline samples, respectively. The influence of different Al2O3 sublayers (e.g. SiO2, Si3N4) and annealing conditions on the diffusion process will be discussed.

Published
2009

19. Conductivity and Charge Trapping After Electrical Stress in Amorphous and Polycrystalline $\hbox{Al}_{2}\hbox{O}_{3}\hbox{-Based}$ Devices Studied With AFM-Related Techniques

Author

Lanza, Mario, primary, Porti, Marc, additional, Nafría, Montserrat, additional, Aymerich, Xavier, additional, Benstetter, Günther, additional, Lodermeier, Edgar, additional, Ranzinger, Heiko, additional, Jaschke, Gert, additional, Teichert, Steffen, additional, Wilde, Lutz, additional, and Michalowski, Pawel Piotr, additional

Published
2011
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20. Conductivity and Charge Trapping After Electrical Stress in Amorphous and Polycrystalline \Al2\O3\-Based Devices Studied With AFM-Related Techniques.

Author

Lanza, Mario, Porti, Marc, Nafría, Montserrat, Aymerich, Xavier, Benstetter, Günther, Lodermeier, Edgar, Ranzinger, Heiko, Jaschke, Gert, Teichert, Steffen, Wilde, Lutz, and Michalowski, Pawel Piotr

Abstract

In this paper, atomic force microscopy-based techniques have been used to study, at nanoscale, the dependence of the electrical properties of \Al2\O3 stacks for flash memories on the annealing temperature (TA). The electrical characterization has been combined with other techniques (for example, transmission electron microscopy) that have allowed to investigate the dependence of the stack crystallization and the Si diffusion from the substrate to the gate oxide on TA. The combination of both the analyses has allowed to explore if there is a relation between the percentage of diffused silicon and material crystallization with the conductivity and charge trapping of \Al2\O3 stacks. [ABSTRACT FROM PUBLISHER]

Published
2011
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