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TRI3DYN Application Examples

1. Shaping and Atomic Mixing of Nanostructures       
2. Doping of Nanostructures
3. Focused Ion Beam Erosion
4. Ion-Beam Based Metrology
5. Plasma-Wall Interaction in Fusion Devices
6. Surface Patterning
7. Magnetron Sputtering

Shaping and Atomic Mixing of Nanostructures            

Foto: Interlayer mixing by a focused ion beam ©Copyright: Prof. Dr. Wolfhard Möller

Source: W. Möller, work supported by the European Union under Grant Agreement No. 688072 - IONS4SET

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Interlayer mixing by a focused ion beam:

Si wafer with a SiO2 interlayer of 7 nm thickness under irradiation with 25 keV Ne+ ions in a He-Ne microscope at increasing number of ions. For the TRI3DYN simulation, a 2D Gaussian beam profile with an FWHM of 5 nm has been assumed, with a beam scan across an area of 3 x 3 nm2. The graphs demonstrate the role of the subsurface beam spread and the forward recoil displacement for the 3D mixing between the Si bulk and the interlayer, as well as the surface erosion by sputtering. The results have been averaged over a central slice of 1,33 nm.


Foto: Ion Mixing in a core/shell nanosphere ©Copyright: M. Mousley

Graphic: M. Mousley (loc. cit.)

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Ion Mixing in a core/shell nanosphere:

Au (15 nm diameter) / SiO2 (60 nm diameter) core/shell nanosphere on C initially (a,e) and after irradiation with 20 keV He ions at normal incidence and fluences of 1·1017 cm-2 (b,f), 2,5·1017 cm-2 (c,g) and 5·1017 cm-2 (d,h). The graphs show Au (a-d; note the logarithmic color code) and Si (e-h) atomic fractions in an azimuthally averaged axial/radial representation. (M. Mousley et al., Scientific Reports 10(2020)12058)


Foto: Ion Mixing and shaping of a stacked nanopillar ©Copyright: Prof. Dr. Wolfhard Möller

Graphic: W. Möller, work supported by the European Union under Grant Agreement No. 688072 - IONS4SET

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Ion Mixing and shaping of a stacked nanopillar:

Stacked conical Si nanopillar with top/bottom diameters of 16/30 nm and a SiO2 interlayer of 6 nm thickness on a Si pedestal, as prepared (top) and after irradiation with 50 keV Si+ ions from top at a fluence of 3·1016 cm-2 (bottom). The simulation result demonstrates a substantial interface mixing of the interlayer, and indicates that ion bombardment may be used to thin the pillar down to a diameter of ~10 nm.


Doping of Nanostructures

Foto: Hyperdoping of a ZnO nanowire ©Copyright: Prof. Dr. Wolfhard Möller

Graphic: W. Möller (loc. cit.)

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Hyperdoping of a ZnO nanowire:

Shaping and Mn atomic density (1024 cm-3) in a ZnO nanowire of initially 150 nm diameter and 1 mm length and on a Si substrate, under irradiation with 175 keV Mn+ ions at an angle of incidence of 45° with respect to the nanowire axis at the fluences indicated. The sample is rotated during irradiation. During the simulation, the system is shifted upwards to retain the full computational volume. The shape and the composition result from a complicated interaction of ion implantation, surface sputtering, atomic mixing and redeposition of sputtered material. (W. Möller et al., Nanotechnology 27(2016)175301)

       


Foto: Se hyperdoping of a Si/SiO2 core-shell nanowire on an oxidized Si substrate ©Copyright: Dr. Yonder Berencen

Source: Y. Berencen (loc. cit.)

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Se hyperdoping of a Si/SiO2 core-shell nanowire on an oxidized Si substrate:

TRI3DYN simulation of high-fluence Se implantation of a Si/SiO2 core/shell NW at 60 keV, an angle of incidence with respect to the surface normal of 7°, and a fluence of 1016 cm-2. (a) Atomic fractions of O (brown), Si (green) and Se (blue; scaled x20); (b) Se atomic density; (c) point defect damage in terms of displacements per atom, with a saturation at 0,5 dpa. The dark contour indicates the transition zone between the amorphized region and the still crystalline region based on the critical point-defect-density model. The grey line contours indicate the original shape of the system. (Y. Berencen et al., Adv. Mater. Interf. (2018)1800101)


Foto: Eu doping of GaN nanowires on a Si substrate ©Copyright: D.N. Faye

Graphic: D.N. Faye (lo. cit)

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Eu doping of GaN nanowires on a Si substrate:

Atomic fractions of Ga, N (color scales: 0 = red to 0,6 = blue) and Eu (color scale: 0 = blue to 0,02 = red), and point defect damage (color scale: 0 = red to 60 displacements per atom = blue) in GaN nanowires on Si after 300 keV Eu+ implantation at an angle of incidence of 20° and a fluence of 3·1015 cm-2. In the TRI3DYN simulation, the lateral extension of the computational volume has been adjusted in such a way that periodic boundary conditions mimic a dense array of nanowires of 100 nm diameter with an areal density of 7·109 cm-2. (D.N. Faye et al., J. Phys. Chem C 123(2019)11874)


Focused Ion Beam Erosion

Foto: Erosion of Pt by Ga focused ion beam (FIB) Irradiation ©Copyright: Prof. Dr. Wolfhard Möller

Graphic: W. Möller

Erosion of Pt by Ga focused ion beam (FIB) Irradiation:

A 30 keV Ga+ FIB is scanned at normal incidence across an area of 23,4x31,7 nm2 with a meander-like sequence of 50x50 beam spots of 1 nm diameter, each containing 10 ions. The evolution of the surface voxels (left, seen from bottom) shows the pit formation after incidence of 2,55·105, 5,10·105, 1,27·106 and 2,55·106 ions (from top to bottom).

Foto: Erosion of Pt by Ga focused ion beam (FIB) Irradiation 2 ©Copyright: Prof. Dr. Wolfhard Möller

Source: W. Möller

 The eroded depth (in the center of the pits) versus the nr. of incident ions demonstrates the convergence towards a final depth due to redeposition of the sputtered atoms at the walls.

Foto: Erosion of Pt by Ga focused ion beam (FIB) Irradiation 3 ©Copyright: Prof. Dr. Wolfhard Möller

Source: W. Möller

The central cross section through the final structure (at 2,55·106 ions; averaged over a slice of 4 nm thickness) demonstrates a sizeable in-depth contamination with Ga due to redeposition and recoil implantation. It should, however, be noted that the simulation neglects any diffusion  of Ga to the surface, which will reduce the Ga contamination and may also influence the sputtering and thereby the erosion speed as well as the final depth of the pit.


Ion-Beam Based Metrology

Foto: Sample preparation by focused ion beam irradiation ©Copyright: Prof. Dr. Wolfhard Möller

Source: W. Möller

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Sample preparation by focused ion beam irradiation:

TRI3DYN model simulation of sputter erosion (top), Ga incorporation (middle) and damage generation (bottom) during 5 keV Ga+ irradiation of Si at a glancing angle of 85° with respect to the surface normal. The beam with a uniform circular profile of 5 nm diameter is scanned over an area of 45 nm (the sample width) x 6,5 nm2, as indicated by the grey rectangles. The Ga and damage data have been averaged over a central slice of 9 nm thickness.  A damage saturation at 1 displacement per atom has been assumed. Despite of the low energy and glancing incidence, a sizeable Ga incorporation and significant damage down to a few nm is predicted.


Foto: Sputter depth profiling of a fin/multilayer quantum well structure ©Copyright: W. Hourani

Graphic: W. Möller

Sputter depth profiling of a fin/multilayer quantum well structure:

Foto: Sputter depth profiling of a fin/multilayer quantum well structure 2 ©Copyright: W. Hourani

Graphic: W. Möller

Periodically arranged SiO2 fins in an 8 nm GaAs / 10 nm AlAs / 16 nm GaAs / 10 nm AlAs / 140 nm GaAs multilayer on Si (see W. Hourani et al.,  J. Electr. Spectrosc. Rel. Phenom. 213(2016)1), as prepared (a) and after irradiation with 500 eV Ar+ ions incident at 62° with respect to the surface normal and perpendicular to the fins (from the right in the graphs), at fluences of 5·1016 cm-2 (b) and 2,5·1017 cm-2 (c). Any Ar incorporation has been neglected. In the simulation with periodic lateral boundary conditions, the eroded structure is dynamically adjusted to the top in order to fill the entire computational volume. The dynamic development of the elemental sputtering yields and the average surface composition is shown in (d) and (e), respectively. The simulation can thus help to understand dynamic SIMS and AES results, respectively.    


Foto: Ion transmission microscopy in an He ion microscope ©Copyright: Prof. Dr. Wolfhard Möller

Source: W. Möller, work supported by the FIT4NANO COST action

Ion transmission microscopy in an He ion microscope:

Ion transmission image (top) and sample degradation at a fluence of 2·1016 cm-2 (bottom) from 20 keV He+ irradiation of a Au (20 nm diam.) / SiO2 (50 nm diam.) core/shell nanosphere on a Si3N4 membrane of 20 nm thickness. The detector is mounted 2,5 cm behind the sample with an annular sensitive area of an inner and outer diameter of 0,6 cm and 5 cm, respectively, for dark-field imaging. A special evaluation software correlates the detection of the forward scattered ions with the actual x-y scan position of the beam on the sample, which is registered in 30 x 30 pixels (top). The color scale in the transmission image denotes the number of scattered ions per pixel relative to the total number of incident ions. The TRI3DYN simulation helps to the define the detector conditions for optimum image contrast. It also indicates that an image of reasonable quality can be obtained without any serious degradation of the sample by sputtering or atomic mixing (bottom, with the data averaged over a central slice of 2 nm thickness). 

Foto: Ion transmission microscopy in an He ion microscope2 ©Copyright: Prof. Dr. Wolfhard Möller

Source: W. Möller, work supported by the FIT4NANO COST action


Plasma-Wall Interaction in Fusion Devices

Foto: Sputter erosion of nanostructured W 2 ©Copyright: R. Stadlmayr

Graphic: R. Stadlmayr (loc. cit.)

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Sputter erosion of nanostructured W:

Randomly generated model structure of a nanostructured W surface (“W-fuzz”), as initially randomly generated (left), and from TRI3DYN simulation after irradiation with 2 keV Ar ions at an incidence angle of 60° with respect to the average surface normal, at a fluence of 1,7·1018 cm-2  (bottom). 3D images (a) as well as top views (b) and views along the x-z plane with 60° inclination (c) are shown. At increasing fluence, the surface gets flattened and develops a cone-like structure along the incident beam. (R. Stadlmayr et al., J. Nucl. Mater. 532(2020)152019)

Foto: Sputter erosion of nanostructured W ©Copyright: R. Stadlmayr

Graphic: R. Stadlmayr (loc. cit.)

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Surface Patterning

Foto: Surface patterning under noble gas irradiation ©Copyright: Prof. Dr. Wolfhard Möller

Graphic: W. Möller (loc. cit.)

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Surface patterning under noble gas irradiation:

Eroded depth (a), surface roughness (b) and surface contours (c) for 200 eV Xe+ irradiation of C at an angle of incidence of 60° with respect to the surface normal and increasing fluence, from a TRI3DYN simulation with a lateral field of 40x40 nm2 at periodic boundary conditions. A pronounced ripple pattern is developed with a wave vector parallel to the direction of incidence. The incorporation of Xe is neglected. (W. Möller, Nucl. Instrum. Meth. B 322(2014)23)


Magnetron Sputtering

Foto: Erosion of a circular magnetron target ©Copyright: W. Möller

Bild: W. Möller

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Erosion of a circular magnetron target:

Sputter erosion of a Cu target of 5 cm thickness and 10 cm diameter by 500 eV Ar+ bombardment from the plasma, for which a circular toroidal Gaussian beam profile of 3 cm radius and an FWHM of 1 cm is assumed. The ion fluences are 2·1023 cm-2 (top) and 4·1023 cm-2 (bottom). The images show only the surface voxels of the half-target. The color code indicates the local height.


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