Werner Wesch - Academia.edu (original) (raw)

Papers by Werner Wesch

Thin Solid Films, 2013

ABSTRACT The effect of 700 keV In implantation and subsequent annealing on GaN was studied by Rut... more ABSTRACT The effect of 700 keV In implantation and subsequent annealing on GaN was studied by Rutherford Backscattering spectroscopy, Raman spectroscopy and nanο-indentation as a function of the ion fluence (F) ranging from 5 × 1013 to 1 × 1016 cm− 2. Symmetry allowed and disorder activated Raman scattering peaks were analyzed using the spatial correlation model, allowing their assignment to phonon branches of crystalline GaN or defects and the estimation of the corresponding phonon coherence length (L). The L values decrease abruptly at a critical fluence of approximately 2 × 1014 cm− 2. After a slight increase in the nano-hardness (H) and reduced elastic modulus (Er) values at low implantation fluences, they exhibit a steep reduction. These variations are accompanied by changes in the shape of the load–displacement curves, which are indicative of elasto-plastic behavior up to a critical F, whereas they approach the ideal plastic behavior at higher fluences. Annealing at 1000 °C of the sample implanted with 1 × 1015 ions/cm2 results in efficient recovery of its structural and nano-mechanical properties. However, annealing of specimens implanted at higher fluences causes partial recovery that starts mainly from the transition region between the heavily damaged and the underlying undamaged GaN. The highly correlated behavior of L, H and Er on the implantation fluence implies a common origin of the studied effects.

Springer Series in Surface Sciences, 2016

In this chapter the structural modification of crystalline semiconductors due to swift heavy ion ... more In this chapter the structural modification of crystalline semiconductors due to swift heavy ion (SHI) irradiation induced high electronic excitation is discussed. After a short description of the energy deposition processes, experimental results on ion track and damage formation in various semiconductors are presented. The results highlight the different susceptibility of the materials to SHI induced damage formation and the existence of material specific threshold values of the electronic energy deposition for track formation. The results are discussed in the framework of existing models and it is shown that the experimental data can be well described using an extended inelastic thermal spike model.

Fracture of Nano and Engineering Materials and Structures

The investigation of radiation effects in III–V semiconductors is of current interest because of ... more The investigation of radiation effects in III–V semiconductors is of current interest because of the potential application of ion implantation in the production of electronic and photonic devices. Of the plethora of III–V semiconductors, gallium nitride (GaN) has attracted keen interest, during past decade, as wide gap semiconductor for numerous applications, including high-power or high frequency devices and high-power switches. Although there is considerable interest in determining the influence of ion implantation on the mechanical properties of GaN films, the matter has received only scant attention, see for example Kavouras et al. [1]. Indeed, studies of the processes controlling hardness, contact damage and cracking of epitaxially grown GaN films have significant technological importance.

physica status solidi (c), 2008

Ar+ ions were implanted into Ge samples with (100), (110), (111) and (112) orientations at 15 K w... more Ar+ ions were implanted into Ge samples with (100), (110), (111) and (112) orientations at 15 K with fluences ranging from 1 × 1011 to 1 × 1014 cm−2. The Rutherford backscattering (RBS) technique in the channelling orientation was used to study the damage build-up in situ. Implantation and RBS measurements were performed without changing the target temperature. The samples were mounted on a four axis goniometer cooled by a close cycle He cryostat. The implantations were performed with the surface being tilted 7° off the ion beam direction to prevent channelling effects. After each 300 keV Ar+ implantation, RBS analysis performed with 1.4 MeV He+ ions. The damage efficiency per ion was found to be Pa =4.5 × 10−14 cm−2. There is no significant difference in the values found for the four different orientations. This, together with the high value (5 times higher than that found in Si), gives rise to the assumption of amorphous pocket formation per incident ion, i.e. direct impact amorphisation, already at low implantation fluences. At higher fluences, when collision cascades overlap, there is a growth of the already amorphised regions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

The synthesis of materials combining ferromagnetism and semiconducting properties is of great int... more The synthesis of materials combining ferromagnetism and semiconducting properties is of great interest for the development of devices for future electronics. In order to form magnetic clusters embedded in crystalline Si, sequential ion implantation of As + and Mn + was performed with ion fluences in the order of 10 16 at/cm 2 per ion species and ion energies of 270 keV (As) and 200 keV (Mn), respectively. Based on investigations with Rutherford backscattering spectrometry (RBS) and ferromagnetic resonance (FMR) measurements, we report on our observations regarding the influence of rapid thermal annealing (RTA) on the structural properties of As and Mn co-implanted Si, the redistribution of the implanted elements and the potential relevance to the appearance of ferromagnetism. On the annealed sample with the best magnetic characteristics, nano-sized Mn-and As-rich clusters have been directly identified by transmission electron microscopy (TEM).

Nanotechnology, 2014

Silver nanoparticles (NPs) embedded in lithium niobate were fabricated via ion beam synthesis and... more Silver nanoparticles (NPs) embedded in lithium niobate were fabricated via ion beam synthesis and are suitable for various plasmonic applications, e.g. enhancement of optical nonlinear effects. After room temperature silver implantation, annealing in the temperature range of 400-600 °C was performed in order to recrystallize the damaged lithium niobate surface layer. The shape of the silver NPs, their optical properties as well as the structural properties of their surrounding matrix have been analyzed for various annealing steps. TEM investigations show that annealing at 400 °C does not lead to recrystallization of the damaged lithium niobate. A recrystallization occurs upon increasing the annealing temperature to 500 or 600 °C, but simultaneously a second phase consisting of lithium triniobate forms. This is additionally supported by XRD measurements. By utilizing dynamic annealing, i.e. implanting silver at elevated temperatures of 400 °C, it is shown that the LiNbO3 matrix stays single crystalline during ion implantation and no LiNb3O8 is formed. This is additionally verified by comparing the positions of the surface plasmon resonances with calculations based on Mie's scattering theory.

Journal of Physics D: Applied Physics, 2008

In order to investigate the formation of Mn/Sb clusters embedded in crystalline silicon, sequenti... more In order to investigate the formation of Mn/Sb clusters embedded in crystalline silicon, sequential ion implantation with fluences of 1 × 1016 at cm-2 and 2 × 1016 at cm-2, respectively, was used to incorporate Mn and Sb ions at high concentrations into Si(0 0 1). Based on investigations with Rutherford backscattering spectroscopy (RBS) and corresponding channelling measurements (RBS/c), we

Journal of Physics: Conference Series, 2008

In this work we report firstly on the behaviour of Schottky barrier diodes (SBD's... more In this work we report firstly on the behaviour of Schottky barrier diodes (SBD's) when subjected to thermal treatment after metallization. To better understand this, a systematic study of the interaction between thin gold films and crystalline germanium substrates was undertaken. Gold metal films having thicknesses of 30 and 100 nm have been prepared by means of thermal evaporation on

Journal of Nuclear Materials, 2009

Diffusion of silver in 6H-SiC and polycrystalline CVD-SiC was investigated using a-particle chann... more Diffusion of silver in 6H-SiC and polycrystalline CVD-SiC was investigated using a-particle channeling spectroscopy and electron microscopy. Fluences of 2 Â 10 16 cm À2 of 109 Ag + were implanted with an energy of 360 keV at room temperature, at 350°C and 600°C, producing an atomic density of approximately 2% at the projected range of about 110 nm. The broadening of the implantation profile and the loss of silver through the front surface during vacuum annealing at temperatures up to 1600°C was determined. Fairly strong silver diffusion was observed after an initial 10 h annealing period at 1300°C in both polycrystalline and single crystalline SiC, which is mainly due to implant induced radiation damage. After further annealing at this temperature no additional diffusion took place in the 6H-SiC samples, while it was considerably reduced in the CVD-SiC. The latter was obviously due to grain boundary diffusion and could be described by the Fick diffusion equation. Isochronal annealing of CVD-SiC up to 1400°C exhibited an Arrhenius type temperature dependence, from which a frequency factor D o $ 4 Â 10 À12 m 2 s À1 and an activation energy E a $ 4 Â 10 À19 J could be extracted. Annealing of 6H-SiC above 1400°C shifted the silver profile without any broadening towards the surface, where most of the silver was released at 1600°C. Electron microscopy revealed that this process was accompanied by significant restructuring of the surface region. An upper limit of D < 10 À21 m 2 s À1 was estimated for 6H-SiC at 1300°C.

Journal of Applied Physics, 2000

ABSTRACT The semiconductor materials Si, SiC, GaP, InP, GaAs, and InAs were irradiated at normal ... more ABSTRACT The semiconductor materials Si, SiC, GaP, InP, GaAs, and InAs were irradiated at normal incidence and room temperature with a focused Ga+ ion beam in order to investigate the damage production at high current densities on the order of some A cm−2. The samples were irradiated with ion fluences between 2×1013 and 2×1015 Ga+ cm−2 at an ion energy of 50 keV. The critical ion fluences for amorphization were determined by Rutherford backscattering spectrometry and by Raman spectroscopy. It was found that for SiC, GaP, and InP the number of displacements per atom necessary for amorphization is about the same one as that required for irradiation at low current densities, but in the cases of Si, GaAs, and InAs the high and low current density results differ remarkably. The reason for the different behavior of these materials is discussed. © 2000 American Institute of Physics.

Applied Physics Letters, 2005

N, Ar, and Er ions were implanted into ZnO at 15 K within a large fluence range. The Rutherford b... more N, Ar, and Er ions were implanted into ZnO at 15 K within a large fluence range. The Rutherford backscattering technique in the channeling mode was used to study in situ the damage built-up in the Zn sublattice at 15 K. Several stages in the damage formation were observed. From the linear increase of the damage for low implantation fluences, an upper limit of the Zn displacement energy of 65 eV could be estimated for ͓0001͔ oriented ZnO. Annealing measurements below room temperature show a significant recovery of the lattice starting at temperatures between 80 and 130 K for a sample implanted with low Er fluence. Samples with higher damage levels do not reveal any damage recovery up to room temperature, pointing to the formation of stable defect complexes.

Applied Physics A, 2013

An attempt has been made to achieve the crystallization of silicon thin film on metallic foils by... more An attempt has been made to achieve the crystallization of silicon thin film on metallic foils by long pulse duration excimer laser processing. Amorphous silicon thin films (100 nm) were deposited by radiofrequency magnetron sputtering on a commercial metallic alloy (N42-FeNi made of 41 % of Ni) coated by a tantalum nitride (TaN) layer. The TaN coating acts as a barrier layer, preventing the diffusion of metallic impurities in the silicon thin film during the laser annealing. An energy density threshold of 0.3 J cm −2 , necessary for surface melting and crystallization of the amorphous silicon, was predicted by a numerical simulation of laserinduced phase transitions and witnessed by Raman analysis. Beyond this fluence, the melt depth increases with the intensification of energy density. A complete crystallization of the layer is achieved for an energy density of 0.9 J cm −2 .

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

Epitaxial silicon nanowires were grown on gold (Au) implanted silicon substrates by chemical vapo... more Epitaxial silicon nanowires were grown on gold (Au) implanted silicon substrates by chemical vapour deposition (CVD). We studied the gold droplet formation upon annealing of the Au implanted silicon and discuss the gold droplets capability to catalyze the vapourliquid-solid (VLS) growth of silicon nanowires. Furthermore, we investigated the annealing behaviour of implanted gallium, indium, and aluminum in silicon and discuss why and how they differ from gold. It was found that they do not easily serve as a template for VLS nanowire growth.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Because of their specific physical properties A ,Bv compound semiconductors are widely used for t... more Because of their specific physical properties A ,Bv compound semiconductors are widely used for the fabrication of special electronic and optoelectronic devices. For a planar technology ion implantation seems to be the most promising doping method for these materials because the conventional diffusion technology is complicated due to the thermal instability of the materials, and the fabrication of epitaxial layers with parameters required for these purposes is connected with high costs. Besides that ion implantation offers the advantages already known from the silicon technology. However, in the compound semiconductors the variety of possible native defects is higher than in the elementary semiconductors, and the influence of the implantation parameters on the kind and concentration of defects produced during ion implantation is much more pronounced in these materials compared to silicon. As a consequence the annealing of damage as well as the electrical activation of the dopants are more complex processes than in silicon, and the choice of the annealing parameters requires information about kind and concentration of defects produced in the materials. The present paper gives a brief review about damage production connected with ion implantation in GaAs, GaP, InP and InAs. The influence of ion mass, ion fluence, dose rate and implantation temperature on the remaining damage is discussed. Additionally, an overview of the use of different annealing methods (conventional, laser and rapid thermal annealing) for the electrical activation of dopants, especially in ion implanted GaAs layers, is given .

Radiat Eff Defect Solid, 1980

Thin Solid Films, 2011

Polycrystalline cadmium telluride layers were implanted with phosphorus (P) in order to obtain an... more Polycrystalline cadmium telluride layers were implanted with phosphorus (P) in order to obtain an enhanced p-type doping close to the back contact of CdTe solar cells. The implantation parameters were adjusted based on computer simulations using SRIM. While the implantation profile was kept constant, different CdTe layer thicknesses were investigated. Furthermore, different annealing and activation processes and their influence on the P distribution in the device as well as ion beam induced damage were investigated. The P level was identified by photoluminescence measurements, the effective doping was investigated by means of capacitance–voltage measurements, and the effect on the solar cell properties was analyzed by current voltage characteristics. The results show the P distribution in the CdTe layer to depend strongly on the thermal and chemical post-implantation treatment. The effect of the P-doping on the solar cell properties becomes obvious by an increase of the open-circuit voltage due to the implantation.

2009 IEEE/LEOS Winter Topicals Meeting Series, 2009

ABSTRACT A photonic crystal defect waveguide fabricated in a freestanding LiNbO3 membrane is pres... more ABSTRACT A photonic crystal defect waveguide fabricated in a freestanding LiNbO3 membrane is presented. The three dimensional patterning was done by means of ion-beam enhanced etching.

Thin Solid Films, 2013

ABSTRACT The effect of 700 keV In implantation and subsequent annealing on GaN was studied by Rut... more ABSTRACT The effect of 700 keV In implantation and subsequent annealing on GaN was studied by Rutherford Backscattering spectroscopy, Raman spectroscopy and nanο-indentation as a function of the ion fluence (F) ranging from 5 × 1013 to 1 × 1016 cm− 2. Symmetry allowed and disorder activated Raman scattering peaks were analyzed using the spatial correlation model, allowing their assignment to phonon branches of crystalline GaN or defects and the estimation of the corresponding phonon coherence length (L). The L values decrease abruptly at a critical fluence of approximately 2 × 1014 cm− 2. After a slight increase in the nano-hardness (H) and reduced elastic modulus (Er) values at low implantation fluences, they exhibit a steep reduction. These variations are accompanied by changes in the shape of the load–displacement curves, which are indicative of elasto-plastic behavior up to a critical F, whereas they approach the ideal plastic behavior at higher fluences. Annealing at 1000 °C of the sample implanted with 1 × 1015 ions/cm2 results in efficient recovery of its structural and nano-mechanical properties. However, annealing of specimens implanted at higher fluences causes partial recovery that starts mainly from the transition region between the heavily damaged and the underlying undamaged GaN. The highly correlated behavior of L, H and Er on the implantation fluence implies a common origin of the studied effects.

Springer Series in Surface Sciences, 2016

In this chapter the structural modification of crystalline semiconductors due to swift heavy ion ... more In this chapter the structural modification of crystalline semiconductors due to swift heavy ion (SHI) irradiation induced high electronic excitation is discussed. After a short description of the energy deposition processes, experimental results on ion track and damage formation in various semiconductors are presented. The results highlight the different susceptibility of the materials to SHI induced damage formation and the existence of material specific threshold values of the electronic energy deposition for track formation. The results are discussed in the framework of existing models and it is shown that the experimental data can be well described using an extended inelastic thermal spike model.

Fracture of Nano and Engineering Materials and Structures

The investigation of radiation effects in III–V semiconductors is of current interest because of ... more The investigation of radiation effects in III–V semiconductors is of current interest because of the potential application of ion implantation in the production of electronic and photonic devices. Of the plethora of III–V semiconductors, gallium nitride (GaN) has attracted keen interest, during past decade, as wide gap semiconductor for numerous applications, including high-power or high frequency devices and high-power switches. Although there is considerable interest in determining the influence of ion implantation on the mechanical properties of GaN films, the matter has received only scant attention, see for example Kavouras et al. [1]. Indeed, studies of the processes controlling hardness, contact damage and cracking of epitaxially grown GaN films have significant technological importance.

physica status solidi (c), 2008

Ar+ ions were implanted into Ge samples with (100), (110), (111) and (112) orientations at 15 K w... more Ar+ ions were implanted into Ge samples with (100), (110), (111) and (112) orientations at 15 K with fluences ranging from 1 × 1011 to 1 × 1014 cm−2. The Rutherford backscattering (RBS) technique in the channelling orientation was used to study the damage build-up in situ. Implantation and RBS measurements were performed without changing the target temperature. The samples were mounted on a four axis goniometer cooled by a close cycle He cryostat. The implantations were performed with the surface being tilted 7° off the ion beam direction to prevent channelling effects. After each 300 keV Ar+ implantation, RBS analysis performed with 1.4 MeV He+ ions. The damage efficiency per ion was found to be Pa =4.5 × 10−14 cm−2. There is no significant difference in the values found for the four different orientations. This, together with the high value (5 times higher than that found in Si), gives rise to the assumption of amorphous pocket formation per incident ion, i.e. direct impact amorphisation, already at low implantation fluences. At higher fluences, when collision cascades overlap, there is a growth of the already amorphised regions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

The synthesis of materials combining ferromagnetism and semiconducting properties is of great int... more The synthesis of materials combining ferromagnetism and semiconducting properties is of great interest for the development of devices for future electronics. In order to form magnetic clusters embedded in crystalline Si, sequential ion implantation of As + and Mn + was performed with ion fluences in the order of 10 16 at/cm 2 per ion species and ion energies of 270 keV (As) and 200 keV (Mn), respectively. Based on investigations with Rutherford backscattering spectrometry (RBS) and ferromagnetic resonance (FMR) measurements, we report on our observations regarding the influence of rapid thermal annealing (RTA) on the structural properties of As and Mn co-implanted Si, the redistribution of the implanted elements and the potential relevance to the appearance of ferromagnetism. On the annealed sample with the best magnetic characteristics, nano-sized Mn-and As-rich clusters have been directly identified by transmission electron microscopy (TEM).

Nanotechnology, 2014

Silver nanoparticles (NPs) embedded in lithium niobate were fabricated via ion beam synthesis and... more Silver nanoparticles (NPs) embedded in lithium niobate were fabricated via ion beam synthesis and are suitable for various plasmonic applications, e.g. enhancement of optical nonlinear effects. After room temperature silver implantation, annealing in the temperature range of 400-600 °C was performed in order to recrystallize the damaged lithium niobate surface layer. The shape of the silver NPs, their optical properties as well as the structural properties of their surrounding matrix have been analyzed for various annealing steps. TEM investigations show that annealing at 400 °C does not lead to recrystallization of the damaged lithium niobate. A recrystallization occurs upon increasing the annealing temperature to 500 or 600 °C, but simultaneously a second phase consisting of lithium triniobate forms. This is additionally supported by XRD measurements. By utilizing dynamic annealing, i.e. implanting silver at elevated temperatures of 400 °C, it is shown that the LiNbO3 matrix stays single crystalline during ion implantation and no LiNb3O8 is formed. This is additionally verified by comparing the positions of the surface plasmon resonances with calculations based on Mie&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s scattering theory.

Journal of Physics D: Applied Physics, 2008

In order to investigate the formation of Mn/Sb clusters embedded in crystalline silicon, sequenti... more In order to investigate the formation of Mn/Sb clusters embedded in crystalline silicon, sequential ion implantation with fluences of 1 × 1016 at cm-2 and 2 × 1016 at cm-2, respectively, was used to incorporate Mn and Sb ions at high concentrations into Si(0 0 1). Based on investigations with Rutherford backscattering spectroscopy (RBS) and corresponding channelling measurements (RBS/c), we

Journal of Physics: Conference Series, 2008

In this work we report firstly on the behaviour of Schottky barrier diodes (SBD&amp;amp;#39;s... more In this work we report firstly on the behaviour of Schottky barrier diodes (SBD&amp;amp;#39;s) when subjected to thermal treatment after metallization. To better understand this, a systematic study of the interaction between thin gold films and crystalline germanium substrates was undertaken. Gold metal films having thicknesses of 30 and 100 nm have been prepared by means of thermal evaporation on

Journal of Nuclear Materials, 2009

Diffusion of silver in 6H-SiC and polycrystalline CVD-SiC was investigated using a-particle chann... more Diffusion of silver in 6H-SiC and polycrystalline CVD-SiC was investigated using a-particle channeling spectroscopy and electron microscopy. Fluences of 2 Â 10 16 cm À2 of 109 Ag + were implanted with an energy of 360 keV at room temperature, at 350°C and 600°C, producing an atomic density of approximately 2% at the projected range of about 110 nm. The broadening of the implantation profile and the loss of silver through the front surface during vacuum annealing at temperatures up to 1600°C was determined. Fairly strong silver diffusion was observed after an initial 10 h annealing period at 1300°C in both polycrystalline and single crystalline SiC, which is mainly due to implant induced radiation damage. After further annealing at this temperature no additional diffusion took place in the 6H-SiC samples, while it was considerably reduced in the CVD-SiC. The latter was obviously due to grain boundary diffusion and could be described by the Fick diffusion equation. Isochronal annealing of CVD-SiC up to 1400°C exhibited an Arrhenius type temperature dependence, from which a frequency factor D o $ 4 Â 10 À12 m 2 s À1 and an activation energy E a $ 4 Â 10 À19 J could be extracted. Annealing of 6H-SiC above 1400°C shifted the silver profile without any broadening towards the surface, where most of the silver was released at 1600°C. Electron microscopy revealed that this process was accompanied by significant restructuring of the surface region. An upper limit of D < 10 À21 m 2 s À1 was estimated for 6H-SiC at 1300°C.

Journal of Applied Physics, 2000

ABSTRACT The semiconductor materials Si, SiC, GaP, InP, GaAs, and InAs were irradiated at normal ... more ABSTRACT The semiconductor materials Si, SiC, GaP, InP, GaAs, and InAs were irradiated at normal incidence and room temperature with a focused Ga+ ion beam in order to investigate the damage production at high current densities on the order of some A cm−2. The samples were irradiated with ion fluences between 2×1013 and 2×1015 Ga+ cm−2 at an ion energy of 50 keV. The critical ion fluences for amorphization were determined by Rutherford backscattering spectrometry and by Raman spectroscopy. It was found that for SiC, GaP, and InP the number of displacements per atom necessary for amorphization is about the same one as that required for irradiation at low current densities, but in the cases of Si, GaAs, and InAs the high and low current density results differ remarkably. The reason for the different behavior of these materials is discussed. © 2000 American Institute of Physics.

Applied Physics Letters, 2005

N, Ar, and Er ions were implanted into ZnO at 15 K within a large fluence range. The Rutherford b... more N, Ar, and Er ions were implanted into ZnO at 15 K within a large fluence range. The Rutherford backscattering technique in the channeling mode was used to study in situ the damage built-up in the Zn sublattice at 15 K. Several stages in the damage formation were observed. From the linear increase of the damage for low implantation fluences, an upper limit of the Zn displacement energy of 65 eV could be estimated for ͓0001͔ oriented ZnO. Annealing measurements below room temperature show a significant recovery of the lattice starting at temperatures between 80 and 130 K for a sample implanted with low Er fluence. Samples with higher damage levels do not reveal any damage recovery up to room temperature, pointing to the formation of stable defect complexes.

Applied Physics A, 2013

An attempt has been made to achieve the crystallization of silicon thin film on metallic foils by... more An attempt has been made to achieve the crystallization of silicon thin film on metallic foils by long pulse duration excimer laser processing. Amorphous silicon thin films (100 nm) were deposited by radiofrequency magnetron sputtering on a commercial metallic alloy (N42-FeNi made of 41 % of Ni) coated by a tantalum nitride (TaN) layer. The TaN coating acts as a barrier layer, preventing the diffusion of metallic impurities in the silicon thin film during the laser annealing. An energy density threshold of 0.3 J cm −2 , necessary for surface melting and crystallization of the amorphous silicon, was predicted by a numerical simulation of laserinduced phase transitions and witnessed by Raman analysis. Beyond this fluence, the melt depth increases with the intensification of energy density. A complete crystallization of the layer is achieved for an energy density of 0.9 J cm −2 .

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

Epitaxial silicon nanowires were grown on gold (Au) implanted silicon substrates by chemical vapo... more Epitaxial silicon nanowires were grown on gold (Au) implanted silicon substrates by chemical vapour deposition (CVD). We studied the gold droplet formation upon annealing of the Au implanted silicon and discuss the gold droplets capability to catalyze the vapourliquid-solid (VLS) growth of silicon nanowires. Furthermore, we investigated the annealing behaviour of implanted gallium, indium, and aluminum in silicon and discuss why and how they differ from gold. It was found that they do not easily serve as a template for VLS nanowire growth.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Because of their specific physical properties A ,Bv compound semiconductors are widely used for t... more Because of their specific physical properties A ,Bv compound semiconductors are widely used for the fabrication of special electronic and optoelectronic devices. For a planar technology ion implantation seems to be the most promising doping method for these materials because the conventional diffusion technology is complicated due to the thermal instability of the materials, and the fabrication of epitaxial layers with parameters required for these purposes is connected with high costs. Besides that ion implantation offers the advantages already known from the silicon technology. However, in the compound semiconductors the variety of possible native defects is higher than in the elementary semiconductors, and the influence of the implantation parameters on the kind and concentration of defects produced during ion implantation is much more pronounced in these materials compared to silicon. As a consequence the annealing of damage as well as the electrical activation of the dopants are more complex processes than in silicon, and the choice of the annealing parameters requires information about kind and concentration of defects produced in the materials. The present paper gives a brief review about damage production connected with ion implantation in GaAs, GaP, InP and InAs. The influence of ion mass, ion fluence, dose rate and implantation temperature on the remaining damage is discussed. Additionally, an overview of the use of different annealing methods (conventional, laser and rapid thermal annealing) for the electrical activation of dopants, especially in ion implanted GaAs layers, is given .

Radiat Eff Defect Solid, 1980

Thin Solid Films, 2011

Polycrystalline cadmium telluride layers were implanted with phosphorus (P) in order to obtain an... more Polycrystalline cadmium telluride layers were implanted with phosphorus (P) in order to obtain an enhanced p-type doping close to the back contact of CdTe solar cells. The implantation parameters were adjusted based on computer simulations using SRIM. While the implantation profile was kept constant, different CdTe layer thicknesses were investigated. Furthermore, different annealing and activation processes and their influence on the P distribution in the device as well as ion beam induced damage were investigated. The P level was identified by photoluminescence measurements, the effective doping was investigated by means of capacitance–voltage measurements, and the effect on the solar cell properties was analyzed by current voltage characteristics. The results show the P distribution in the CdTe layer to depend strongly on the thermal and chemical post-implantation treatment. The effect of the P-doping on the solar cell properties becomes obvious by an increase of the open-circuit voltage due to the implantation.

2009 IEEE/LEOS Winter Topicals Meeting Series, 2009

ABSTRACT A photonic crystal defect waveguide fabricated in a freestanding LiNbO3 membrane is pres... more ABSTRACT A photonic crystal defect waveguide fabricated in a freestanding LiNbO3 membrane is presented. The three dimensional patterning was done by means of ion-beam enhanced etching.