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Ulrich Kentsch

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u.kentschAthzdr.de
Phone: +49 351 260 3345

Publications - Ion implantation and modification of materials

Here you are finding current publications that have emerged from user experiments and collaborations with the "Ion implantation and modification of materials" group.

Publikations FWIZ-I

Year incl. Online First >= 2019
"Online First" included
OU: Implanter (FWIZ-I)

Energetic Au ion beam implantation of ZnO nanopillars for optical response modulation

Macková, A.; Malinský, P.; Jagerová, A.; Mikšová, R.; Lalik, O.; Nekvindová, P.; Mistrík, J.; Marvan, P.; Sofer, Z.; Holý, V.; Schutter, J. D.; Kentsch, U.; Azarov, A.; Galeckas, A.

Nanopillars of ZnO were implanted with Au-400 keV ions at various ion fluences from 1 × 10¹⁵ cm⁻² to 1 × 10¹⁶ cm⁻² and subsequently annealed at 750 °C for 15 min in order to reduce the implantation damage and to support Au nanoparticle (NP) aggregation. It was found that implantation-induced effects and thermal effects influence the Au NP coalescence as well as the quality of the ZnO nanopillars. Rutherford Back-Scattering spectrometry (RBS) showed the broader Au-depth profiles than it was theoretically predicted, but the Au-concentration maximum agrees well with prediction taking into account the effective ZnO layer density. The implantation at the higher fluences induced the morphology modification of the nanopillar layer evidenced by RBS and scanning electron microscopy (SEM). An indirect evidence of this effect was given by optical ellipsometry due to gradual refractive index changes in the ZnO nanopillars with the increased Au-ion fluence. Optical characterization of the Au-implanted and annealed nanopillars performed by means of photoluminescence (PL) and diffuse-reflectance spectroscopy (DRS) evidenced the surface plasmon resonance (SPR) activity of the embedded Au NPs. The SPR-enhanced scattering and PL emission observed in the spectral range 500–650 nm are ascribed to Au NPs or more complex Au-clusters. In addition, the ellipsometry measurements of extinction coefficient are found to corroborate well results from DRS, both indicating increase of SPR effect with the increase of Au-ion fluence and after the post-annealing.

Keywords: ZnO nanopillars; Au nanoparticles; ion implantation; SPR; doped ZnO nanostructures

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  • Secondary publication expected from 24.02.2023

Direct visualization of highly resistive areas in GaN by means of low-voltage scanning electron microscopy

Jóźwik, I.; Jagielski, J.; Caban, P.; Kamiński, M.; Kentsch, U.

The damage-induced voltage alteration (DIVA) contrast mechanism in scanning
electron microscope (SEM) at low electron energy has been presented as a fast and
convenient method of direct visualization of increased resistivity induced by energetic
ions irradiation in gallium nitride (GaN). Epitaxially grown GaN layers on sapphire
covered with a metallic masks with etched windows were subjected to He 2+
irradiations at 600 keV energy. The resulting two-dimensional damage profiles at the
samples cross-sections were imaged at SEM at different e-beam energies and scan
speeds. The gradual development of image contrast was observed with the increase of
cumulative charge deposited by electron beam irradiation, to finally reach the
saturation level of the contrast related to the local resistivity of the ion-irradiated part of
GaN.
The presented method allows one to directly visualize the ion-irradiated zone even for
the lowest resistivity changes resulting from ion damage, i.e. all levels of insulation
build-up in GaN upon irradiation with ions. Taking into account that it is not possible to
apply the etch-stop technique by wet chemistry to GaN, it makes the presented
technique the only available method of visualization of highly resistant and insulating
regions in GaN-based electronic devices.
Main aim of the presented work is to get a deeper insight into a DIVA contrast in GaN
with the special emphasize to discuss the role of rastering speed and electron beam
current, i.e. details of charge build-up ion the sample surface.

Keywords: GaN; Ion damage; Ion implantation; Low-kV SEM

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Resistivity contrast imaging in semiconductor structures using ultra-low energy scanning electron microscopy

Jozwik, I.; Jagielski, J.; Dumiszewska, E.; Kaminski, M.; Kentsch, U.

The damage-induced voltage alteration (DIVA) contrast mechanism in scanning electron microscope (SEM) has been studied in broad range of the primary electron beam energies, with a special emphasis on the ultra-low energy range. The SEM imaging contrast related to resistivity changes in the In(0.55)Al(0.45)P irradiated with He2+ ions of 600 keV was subjected to an analysis in a range of 10 keV down to 10 eV of primary electron energies. The problem of specimen charging in ultra-low energy range and its effect on the contrast in SEM images has been tackled for the first time. Contrary to expectations based on the classical total emission yield approach, the potentials formed at the highly resistive part of irradiated area led to dramatic increase in the intensity of registered signal for primary electron energies below E1, which can be explained as signal saturation due to potential on the specimen surface acting as repeller for primary electrons. Nevertheless, the experimental data presenting the influence of the beam energy on the potential formation on the surface of an insulating material under electron irradiation have been presented for the first time in ultra-low energy regime.

Keywords: Ion damage; Ion irradiation; Low-kV SEM; Semiconductors

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Impact of low energy ion beams on the properties of rr-P3HT films

Kislyuk, V.; Kotrechko, S.; Trachevskij, V.; Melnyk, A.; Pud, A.; Ogurtsov, N.; Noskov, Y.; Osiponok, M.; Lytvyn, P.; Dzyazko, Y.; Nierobisch, F.; Schneider, A.; Ludewig, F.; Akhmadaliev, S.; Aniol, R.; Kentsch, U.; Krause, M.; Facsko, S.

Two types of ions (fluorine and titanium) are implanted into films of regio-regular poly(3-hexylthiophene-2,5-diyl) (rr-P3HT) spin-coated on glass substrates with subsequent annealing in argon atmosphere to modify their electrical properties and structure. The ion energy and fluence were within 0.2–40 keV and 10¹³–10¹⁵ cm⁻² respectively. The dc resistance enhances after the intensive ion beam treatment while the ac impedance decreases. Ti ion implantation with 40 keV energy and 10¹⁴ cm⁻² fluence induces decrease of the ac impedance by almost two orders of magnitude and appearance of the molecular hydrogen features in ¹H NMR spectrum. The UV–VIS spectra of the films are blue shifted after their exposal to the ion beams, which correlates with the presence of oxygen. The ratio of the oxygen to carbon peak intensities (O1s/C1s) in the XPS spectra is proposed as a measure for the local partial disturbance of the film. EPR spectra demonstrate formation of the paramagnetic states with g factor <2, which is accompanied with the down-field shift of the NMR spectrum. The ion beams are found to have no significant etching effect as per results of the film thickness measurements and AFM images.

Keywords: Ion implantation; rr-P3HT; Doping; Resistance; Ac impedance; Organic electronics

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Erbium-ion implantation of single- and nano-crystalline ZnO

Cajzl, J.; Nekvindova, P.; Jeníčková, K.; Jagerová, A.; Malinský, P.; Remeš, Z.; Neykova, N.; Chang, Y.-Y.; Oswald, J.; Kentsch, U.; Macková, A.

This paper reports on the results of Er+ ion implantation into various ZnO structures - standard single crystal c-plane (0001) ZnO, nanostructured thin films and nanorods. Er+ ions were implanted using an ion implantation energy of 400 keV and implantation fluences in the range of 5×1014 to 5×1015 ions/cm2. Er concentration depth profiles and the degree of crystal damage were measured using Rutherford backscattering spectrometry (RBS) and RBS/channelling (RBS/C). Additionally, Raman spectroscopy was used to analyse structural modifications of the prepared samples. The main focus was placed on the luminescence properties of various ZnO structures. The results showed that the characteristic bands of ZnO, i.e. near-band-edge (NBE) luminescence and deep-level emission (DLE) - that can be influenced by the excitation wavelength - appeared in the spectra of single crystals and nanorods. The characteristic luminescence bands of erbium ions in the NIR region appeared in ZnO single-crystal samples and nano-crystalline films.

Keywords: ZnO; nanocrystalline thin films; nanorods; erbium; ion implantation; luminescence

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Multi-direction channelling study of the Ag:YSZ nanocomposites prepared by ion implantation

Mikšová, R.; Jagerová, A.; Malinský, P.; Harcuba, P.; Veselý, J.; Holý, V.; Kentsch, U.; Macková, A.

The paper reports on implantation damage accumulation, Ag distribution and the interior morphology in different crystallographic orientations of implanted samples of cubic yttria-stabilised zirconia (YSZ). (100)-, (110)- and (111)-oriented YSZ was implanted with 400-keV Ag⁺ ions at ion fluences from 5 × 10¹⁴ to 5 × 10¹⁶ cm⁻². Rutherford backscattering spectrometry (RBS) in the channelling mode (RBS-C), as well as X-ray diffraction (XRD), were used for the quantitative measurement of the lattice disorder and Ag distribution. The defect propagation and Ag accumulation were observed using transmission electron microscopy (TEM) with the energy-dispersive X-ray spectroscopy (EDX). Although similar damage evolution trends were observed along with all channelling directions, the disorder accumulation is lower along the <110> direction than along the <100> and <111> direction. The damage extends much deeper than the theoretically predicted depths. It is attributed to long-range defect migration effects, confirmed by TEM. At the ion fluence of 5 × 10¹⁶ cm⁻², nanometre-sized Ag precipitates were identified in the depth of 30–130 nm based on the Ag concentration–depth profiles determined by RBS.

Keywords: Ag ion-implantation; Yttria-stabilized zirconia; Damage accumulation; Strain relaxation; Nanoparticles

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Contact

Ulrich Kentsch

Head Implanter
u.kentschAthzdr.de
Phone: +49 351 260 3345