Ivo Utke - Academia.edu (original) (raw)

Papers by Ivo Utke

The Journal of Physical Chemistry C, 2016

Analytical and Bioanalytical Chemistry, 2014

Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal ... more Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal values of elemental composition. Optimal composition can result in high performance in a sequence of material synthesis and characterization. Materials combinatorial libraries are typically encountered in the form of a thin film composition gradient which is produced by simultaneous material deposition on a substrate from two or more sources that are spatially separated and chemically different. Fast spatially resolved techniques are needed to characterize structure, composition, and relevant properties of these combinatorial screening samples. In this work, the capability of a glow discharge optical emission spectroscopy (GD-OES) elemental mapping system is extended to nitrogen-based combinatorial libraries with nonconductive components through the use of pulsed radiofrequency power. The effects of operating parameters of the glow discharge and detection system on the achievable spatial resolution were investigated as it is the first time that an rf source is coupled to a setup featuring a push-broom hyperspectral imaging system and a restrictive anode tube GD source. Spatial-resolution optimized conditions were then used to characterize an aluminum nitride/chromium nitride thin-film composition spread. Qualitative elemental maps could be obtained within 16.8 s, orders of magnitude faster than typical techniques. The use of certified reference materials allowed quantitative elemental analysis maps to be extracted from the emission intensity images. Moreover, the quantitative procedure allowed correcting for the inherent emission intensity inhomogeneity in GD-OES. The results are compared to quantitative depth profiles obtained with a commercial GD-OES instrument.

Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal ... more Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal values of elemental composition. Optimal composition can result in high performance in a sequence of material synthesis and characterization. Materials combinatorial libraries are typically encountered in the form of a thin film composition gradient which is produced by simultaneous material deposition on a substrate from two or more sources that are spatially separated and chemically different. Fast spatially resolved techniques are needed to characterize structure, composition, and relevant properties of these combinatorial screening samples. In this work, the capability of a glow discharge optical emission spectroscopy (GD-OES) elemental mapping system is extended to nitrogen-based combinatorial libraries with non-conductive components through the use of pulsed radiofre-quency power. The effects of operating parameters of the glow discharge and detection system on the achievable spatial resolution were investigated as it is the first time that an rf source is coupled to a setup featuring a push-broom hyperspectral imaging system and a restrictive anode tube GD source. Spatial-resolution optimized conditions were then used to characterize an aluminum nitride/chromium nitride thin-film composition spread. Qualitative elemental maps could be obtained within 16.8 s, orders of magnitude faster than typical techniques. The use of certified reference materials allowed quantitative elemental analysis maps to be extracted from the emission intensity images. Moreover, the quantitative procedure allowed correcting for the inherent emission intensity inhomogeneity in GD-OES. The results are compared to quantitative depth profiles obtained with a commercial GD-OES instrument.

Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the sa... more Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the same halogeno and trifluorophosphine ligands is presented. The deposit geometry of lines and freestanding bridges is discussed with respect to electron energy, beam shape, and backscattered electron distribution. Electron beam heating effects are estimated to be negligible in our deposition conditions. Using PF 3 AuCl, lines of percolating gold grains were deposited with electrical resistivities as low as 22µΩcm at room temperature (Au: 2.2µΩcm). Auger electron analysis shows about 60at% Rh in deposits obtained with [RhCl(PF 3 ) 2 ] 2 , however the resistivity of 1Ωcm is high compared to 4.5µΩcm of pure Rh.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005

Individual carbon nanotubes ͑CNTs͒ often occur in randomly dispersed two-dimensional as well as t... more Individual carbon nanotubes ͑CNTs͒ often occur in randomly dispersed two-dimensional as well as three-dimensional configurations that make device fabrication difficult. Making electrical contact to such CNTs is of practical interest. To this end, we make contact to individual metallic single-walled carbon nanotubes ͑SWNTs͒ using the focused electron-beam-induced deposition ͑FEBID͒ of pure gold. The SWNTs are grown by chemical vapor deposition on a flat substrate, and the gold leads are made through FEBID using inorganic metallic precursor gas, chloro͑trifluorophosphine͒gold͑I͒, or AuClPF 3 , in a high vacuum scanning electron microscope. The same scanning electron microscope is also used to image carbon nanotubes, allowing for simultaneous alignment. We find equivalent one-dimensional resistivities for the SWNTs of 10-15 k⍀ / m for both FEBID gold leads and leads deposited using conventional electron-beam lithography ͑EBL͒ and thermal evaporation of gold, suggesting similarly low contact resistances. We use electrostatic force microscopy to verify quantitatively similar contact resistances for one nanotube sample, 10 ͑±6͒ and 54 ͑±6͒ k⍀, for FEBID and EBL leads, respectively, with most voltage dropping across the long metallic SWNT.

Microelectronic Engineering, 2000

Microelectronic Engineering, 2006

We present evidence that the penetration of electrons in solids, typically a few micrometers at t... more We present evidence that the penetration of electrons in solids, typically a few micrometers at the usual acceleration voltages used in electron microscopes, influences the shape of sub-microstructures created by focused electron beam induced deposition. We demonstrate how monitoring the sample current during deposition gives information on the electron scattering. A physical model is proposed and checked on a series

Journal of The Electrochemical Society, 2004

͑hfac͒Cu͑DMB͒ are compared with respect to deposition rates and metal content obtained by focused... more ͑hfac͒Cu͑DMB͒ are compared with respect to deposition rates and metal content obtained by focused electron beam induced deposition. Exposure was performed with 25 keV electrons in a Cambridge S100 scanning electron microscope equipped with a lithography system. Tip deposition rates increase with increasing precursor vapor pressure and range between 47 nm/s for ͑hfac͒Cu͑DMB͒ to about 4 nm/s for Cu͑hfac) 2 . A decay of deposition rates with time, i.e., tip length, is observed. Electric 4-point measurements indicate an insulating behavior of deposited lines for all precursors. In contrast, Cu contents of up to 45-60 atom % were found by Auger electron spectroscopy in thin rectangular deposits using ͑hfac͒Cu͑DMB͒ and ͑hfac͒Cu͑VTMS͒ as precursors. A discussion in terms of monolayer coverage, completeness of precursor molecule dissociation, and precursor stability is presented.

Microelectronic Engineering, 2004

In this paper we describe the fabrication of a two-dimensional photonic band gap structure by foc... more In this paper we describe the fabrication of a two-dimensional photonic band gap structure by focused electron beam induced deposition. Structure geometry is computed in order to create a light-trapping effect at 632 nm wavelength. Deposits produced using tetraethyl orthosilicate (SiO4C8H20) as precursor were studied to determine their chemical composition and geometrical dimensions. The deposited material has a refractive index

Nanotechnology, 2009

Bending and vibration tests performed inside a scanning electron microscope were used to mechanic... more Bending and vibration tests performed inside a scanning electron microscope were used to mechanically characterize high aspect pillars grown by focused electron-beam- (FEB) induced deposition from the precursor Cu(C5HF6O2)2. Supported by finite element (FE) analysis the Young's modulus was determined from load-deflection measurements using cantilever-based force sensing and the material density from additional resonance vibration analysis. The pillar material consisted

Nano Letters, 2006

The fracture strength of silicon nanowires grown on a (111) silicon substrate by the vapor-liquid... more The fracture strength of silicon nanowires grown on a (111) silicon substrate by the vapor-liquid-solid process was measured. The nanowires, with diameters between 100 and 200 nm and a typical length of 2 Ìm, were subjected to bending tests using an atomic force microscopy setup inside a scanning electron microscope. The average strength calculated from the maximum nanowire deflection before

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the sa... more Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the same halogeno and trifluorophosphine ligands is presented. The deposit geometry of lines and freestanding bridges is discussed with respect to electron energy, beam shape, and backscattered electron distribution. Electron beam heating effects are estimated to be negligible in our deposition conditions. Using PF 3 AuCl, lines of percolating gold grains were deposited with electrical resistivities as low as 22µΩcm at room temperature (Au: 2.2µΩcm). Auger electron analysis shows about 60at% Rh in deposits obtained with [RhCl(PF 3 ) 2 ] 2 , however the resistivity of 1Ωcm is high compared to 4.5µΩcm of pure Rh.

Nano Science and Technolgy, 2008

In this chapter the synergies upon the integration of atomic force microscope sensors in scanning... more In this chapter the synergies upon the integration of atomic force microscope sensors in scanning electron and ion microscopes are outlined and applications are presented. Combining the capabilities of the standalone techniques opens the world to nanoscale measurements and process control. The high-resolution microscopy imaging provides direct visual feedback for the analysis of specific sample features and of individual nanostructures. Fundamental static and dynamic mechanics of cantilever beams are reviewed with an emphasis on the usage of the beams as force and mass sensors in a vacuum. Static force sensing is applied to probe the mechanical properties of nanowires in tensile, bending and compression experiments and dynamic force sensing is used for AFM in SEM applications. Cantilever-based dynamic sensing is discussed to measure the mass of material deposited or etched using the electron or ion beam inherent to the microscope.

Optical Measurement Systems for Industrial Inspection III, 2003

Monitoring biological relevant reactions on the single molecule level by the use of fluorescent p... more Monitoring biological relevant reactions on the single molecule level by the use of fluorescent probes has become one of the most promising approaches for understanding a variety of phenomena in living organisms. By applying techniques of fluorescence spectroscopy to labelled molecules a manifold of different parameters becomes accessible i.e. molecular dynamics, energy transfer, DNA fingerprinting, etc... can be monitored at

Signal Processing, 2004

Rare-earth-ion doped KY(WO 4 ) 2 (hereafter KYW) is a promising material for novel solidstate las... more Rare-earth-ion doped KY(WO 4 ) 2 (hereafter KYW) is a promising material for novel solidstate lasers . Low laser threshold, high efficiency, high output powers, and third-order nonlinear effects have stimulated research towards miniaturized thin-film waveguide lasers and amplifiers for future photonic devices. Active films can be fabricated by liquid-phase epitaxy (LPE), pulsed laser deposition, ion implantation, and diffusion bonding .

Microelectronic Engineering, 2006

The distribution of metal-precursors supplied via a gas injection system to the substrate inside ... more The distribution of metal-precursors supplied via a gas injection system to the substrate inside a focused electron beam (FEB) induced deposition system is investigated for the first time. The impinging precursor molecules are thermally decomposed using a heating stage. Resulting deposit thickness profiles obtained from [(PF 3 ) 2 RhCl] 2 , Co 2 (CO) 8 , and (hfac)CuVTMS precursors are determined optically by interference colors or by profilometry. FEB access to the precursor flux peak and the flux peak value itself depend on tube tilt and vertical tube distance to the substrate. Monte Carlo simulation match best the experiments when assuming molecular flow conditions.

Beilstein Journal of Nanotechnology, 2014

A thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking ... more A thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking full advantages of unique properties of each component. In this context, combining TiO 2 nanocrystals and carbon nanotubes (CNTs) offers enhanced photosensitivity and improved photocatalytic efficiency, which is key to achieving sustainable energy and preventing environmental pollution. Hence, it has aroused a tremendous research interest. This report surveys recent research on the topic of synthesis and characterization of the CNT-TiO 2 interface. In particular, atomic layer deposition (ALD) offers a good control of the size, crystallinity and morphology of TiO 2 on CNTs. Analytical transmission electron microscopy (TEM) techniques such as electron energy loss spectroscopy (EELS) in scanning transmission mode provides structural, chemical and electronic information with an unprecedented spatial resolution and increasingly superior energy resolution, and hence is a necessary tool to characterize the CNT-TiO 2 interface, as well as other technologically relevant CNT-metal/metal oxide material systems.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1999

We demonstrate the operation of bottom-emitting vertical cavity surface-emitting lasers ͑VCSELs͒ ... more We demonstrate the operation of bottom-emitting vertical cavity surface-emitting lasers ͑VCSELs͒ with linear mode polarization which is controlled in an arbitrary orientation by the use of patterned metallic mirrors on top of the VCSEL surface. The top mirror is made in the shape of a 200 nm pitch grating, composed of alternating high reflectivity ͑Au͒ and low reflectivity ͑Cr͒ metal lines, whose orientation determines the polarization of the laser mode. The gratings were fabricated by high-resolution ͑Ͻ50 nm͒ electron-beam lithography and lift-off technique, and were aligned with the other parts of the VCSEL structure ͑top electrode, ion-implanted zone͒ fabricated by conventional photolithography. Various types of mirror shapes and sizes were fabricated, including square and circular grating envelopes, as well as circular mirrors with an average ͑radial͒ Gaussian reflectivity.

Optics Letters, 2005

Baida and Van Labeke recently proposed a structure that exhibits a supertransmission of light thr... more Baida and Van Labeke recently proposed a structure that exhibits a supertransmission of light through an array of nanometric coaxial apertures in a metallic film that has been named an annular aperture array (AAA) [Opt. Commun. 209, 17 (2002); Phys. Rev. B 67, 155314 (2003); J. Microsc. 213, 140 ]. We present the first experimental study, to our knowledge, of an AAA structure in the visible region. For technological reasons, the structure under study does not produce a supertransmission of 80% as in Baida and Van Labeke [Opt. Commun. 209, 17 (2002)]. We built the nanostructure and experimentally recorded its

Nanotechnology, 2005

We report on the fabrication of two-dimensional arrays of nano-optical apertures in gold layers b... more We report on the fabrication of two-dimensional arrays of nano-optical apertures in gold layers by electron beam lithography (EBL) on a transparent glass substrate. 30 × 30 µm 2 large arrays of high aspect ratio sub-wavelength cylinders (400 nm diameter with period of 1.81 µm) and annular apertures (diameters 250/330 nm and 310/330 nm inner/outer with period of 600 nm) were patterned in a 750 nm thick resist layer using a high contrast negative tone resist. The resist structures show sharp and vertical edges after development. The 150 nm thick deposited gold layer ensures optical transmission of less than 1.1 × 10 −4 at 633 nm wavelength. White light based optical characterizations agreed with theory predictions and prove the good quality of the structures.

The Journal of Physical Chemistry C, 2016

Analytical and Bioanalytical Chemistry, 2014

Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal ... more Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal values of elemental composition. Optimal composition can result in high performance in a sequence of material synthesis and characterization. Materials combinatorial libraries are typically encountered in the form of a thin film composition gradient which is produced by simultaneous material deposition on a substrate from two or more sources that are spatially separated and chemically different. Fast spatially resolved techniques are needed to characterize structure, composition, and relevant properties of these combinatorial screening samples. In this work, the capability of a glow discharge optical emission spectroscopy (GD-OES) elemental mapping system is extended to nitrogen-based combinatorial libraries with nonconductive components through the use of pulsed radiofrequency power. The effects of operating parameters of the glow discharge and detection system on the achievable spatial resolution were investigated as it is the first time that an rf source is coupled to a setup featuring a push-broom hyperspectral imaging system and a restrictive anode tube GD source. Spatial-resolution optimized conditions were then used to characterize an aluminum nitride/chromium nitride thin-film composition spread. Qualitative elemental maps could be obtained within 16.8 s, orders of magnitude faster than typical techniques. The use of certified reference materials allowed quantitative elemental analysis maps to be extracted from the emission intensity images. Moreover, the quantitative procedure allowed correcting for the inherent emission intensity inhomogeneity in GD-OES. The results are compared to quantitative depth profiles obtained with a commercial GD-OES instrument.

Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal ... more Combinatorial chemistry and high-throughput techniques are an efficient way of exploring optimal values of elemental composition. Optimal composition can result in high performance in a sequence of material synthesis and characterization. Materials combinatorial libraries are typically encountered in the form of a thin film composition gradient which is produced by simultaneous material deposition on a substrate from two or more sources that are spatially separated and chemically different. Fast spatially resolved techniques are needed to characterize structure, composition, and relevant properties of these combinatorial screening samples. In this work, the capability of a glow discharge optical emission spectroscopy (GD-OES) elemental mapping system is extended to nitrogen-based combinatorial libraries with non-conductive components through the use of pulsed radiofre-quency power. The effects of operating parameters of the glow discharge and detection system on the achievable spatial resolution were investigated as it is the first time that an rf source is coupled to a setup featuring a push-broom hyperspectral imaging system and a restrictive anode tube GD source. Spatial-resolution optimized conditions were then used to characterize an aluminum nitride/chromium nitride thin-film composition spread. Qualitative elemental maps could be obtained within 16.8 s, orders of magnitude faster than typical techniques. The use of certified reference materials allowed quantitative elemental analysis maps to be extracted from the emission intensity images. Moreover, the quantitative procedure allowed correcting for the inherent emission intensity inhomogeneity in GD-OES. The results are compared to quantitative depth profiles obtained with a commercial GD-OES instrument.

Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the sa... more Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the same halogeno and trifluorophosphine ligands is presented. The deposit geometry of lines and freestanding bridges is discussed with respect to electron energy, beam shape, and backscattered electron distribution. Electron beam heating effects are estimated to be negligible in our deposition conditions. Using PF 3 AuCl, lines of percolating gold grains were deposited with electrical resistivities as low as 22µΩcm at room temperature (Au: 2.2µΩcm). Auger electron analysis shows about 60at% Rh in deposits obtained with [RhCl(PF 3 ) 2 ] 2 , however the resistivity of 1Ωcm is high compared to 4.5µΩcm of pure Rh.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005

Individual carbon nanotubes ͑CNTs͒ often occur in randomly dispersed two-dimensional as well as t... more Individual carbon nanotubes ͑CNTs͒ often occur in randomly dispersed two-dimensional as well as three-dimensional configurations that make device fabrication difficult. Making electrical contact to such CNTs is of practical interest. To this end, we make contact to individual metallic single-walled carbon nanotubes ͑SWNTs͒ using the focused electron-beam-induced deposition ͑FEBID͒ of pure gold. The SWNTs are grown by chemical vapor deposition on a flat substrate, and the gold leads are made through FEBID using inorganic metallic precursor gas, chloro͑trifluorophosphine͒gold͑I͒, or AuClPF 3 , in a high vacuum scanning electron microscope. The same scanning electron microscope is also used to image carbon nanotubes, allowing for simultaneous alignment. We find equivalent one-dimensional resistivities for the SWNTs of 10-15 k⍀ / m for both FEBID gold leads and leads deposited using conventional electron-beam lithography ͑EBL͒ and thermal evaporation of gold, suggesting similarly low contact resistances. We use electrostatic force microscopy to verify quantitatively similar contact resistances for one nanotube sample, 10 ͑±6͒ and 54 ͑±6͒ k⍀, for FEBID and EBL leads, respectively, with most voltage dropping across the long metallic SWNT.

Microelectronic Engineering, 2000

Microelectronic Engineering, 2006

We present evidence that the penetration of electrons in solids, typically a few micrometers at t... more We present evidence that the penetration of electrons in solids, typically a few micrometers at the usual acceleration voltages used in electron microscopes, influences the shape of sub-microstructures created by focused electron beam induced deposition. We demonstrate how monitoring the sample current during deposition gives information on the electron scattering. A physical model is proposed and checked on a series

Journal of The Electrochemical Society, 2004

͑hfac͒Cu͑DMB͒ are compared with respect to deposition rates and metal content obtained by focused... more ͑hfac͒Cu͑DMB͒ are compared with respect to deposition rates and metal content obtained by focused electron beam induced deposition. Exposure was performed with 25 keV electrons in a Cambridge S100 scanning electron microscope equipped with a lithography system. Tip deposition rates increase with increasing precursor vapor pressure and range between 47 nm/s for ͑hfac͒Cu͑DMB͒ to about 4 nm/s for Cu͑hfac) 2 . A decay of deposition rates with time, i.e., tip length, is observed. Electric 4-point measurements indicate an insulating behavior of deposited lines for all precursors. In contrast, Cu contents of up to 45-60 atom % were found by Auger electron spectroscopy in thin rectangular deposits using ͑hfac͒Cu͑DMB͒ and ͑hfac͒Cu͑VTMS͒ as precursors. A discussion in terms of monolayer coverage, completeness of precursor molecule dissociation, and precursor stability is presented.

Microelectronic Engineering, 2004

In this paper we describe the fabrication of a two-dimensional photonic band gap structure by foc... more In this paper we describe the fabrication of a two-dimensional photonic band gap structure by focused electron beam induced deposition. Structure geometry is computed in order to create a light-trapping effect at 632 nm wavelength. Deposits produced using tetraethyl orthosilicate (SiO4C8H20) as precursor were studied to determine their chemical composition and geometrical dimensions. The deposited material has a refractive index

Nanotechnology, 2009

Bending and vibration tests performed inside a scanning electron microscope were used to mechanic... more Bending and vibration tests performed inside a scanning electron microscope were used to mechanically characterize high aspect pillars grown by focused electron-beam- (FEB) induced deposition from the precursor Cu(C5HF6O2)2. Supported by finite element (FE) analysis the Young's modulus was determined from load-deflection measurements using cantilever-based force sensing and the material density from additional resonance vibration analysis. The pillar material consisted

Nano Letters, 2006

The fracture strength of silicon nanowires grown on a (111) silicon substrate by the vapor-liquid... more The fracture strength of silicon nanowires grown on a (111) silicon substrate by the vapor-liquid-solid process was measured. The nanowires, with diameters between 100 and 200 nm and a typical length of 2 Ìm, were subjected to bending tests using an atomic force microscopy setup inside a scanning electron microscope. The average strength calculated from the maximum nanowire deflection before

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the sa... more Electron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the same halogeno and trifluorophosphine ligands is presented. The deposit geometry of lines and freestanding bridges is discussed with respect to electron energy, beam shape, and backscattered electron distribution. Electron beam heating effects are estimated to be negligible in our deposition conditions. Using PF 3 AuCl, lines of percolating gold grains were deposited with electrical resistivities as low as 22µΩcm at room temperature (Au: 2.2µΩcm). Auger electron analysis shows about 60at% Rh in deposits obtained with [RhCl(PF 3 ) 2 ] 2 , however the resistivity of 1Ωcm is high compared to 4.5µΩcm of pure Rh.

Nano Science and Technolgy, 2008

In this chapter the synergies upon the integration of atomic force microscope sensors in scanning... more In this chapter the synergies upon the integration of atomic force microscope sensors in scanning electron and ion microscopes are outlined and applications are presented. Combining the capabilities of the standalone techniques opens the world to nanoscale measurements and process control. The high-resolution microscopy imaging provides direct visual feedback for the analysis of specific sample features and of individual nanostructures. Fundamental static and dynamic mechanics of cantilever beams are reviewed with an emphasis on the usage of the beams as force and mass sensors in a vacuum. Static force sensing is applied to probe the mechanical properties of nanowires in tensile, bending and compression experiments and dynamic force sensing is used for AFM in SEM applications. Cantilever-based dynamic sensing is discussed to measure the mass of material deposited or etched using the electron or ion beam inherent to the microscope.

Optical Measurement Systems for Industrial Inspection III, 2003

Monitoring biological relevant reactions on the single molecule level by the use of fluorescent p... more Monitoring biological relevant reactions on the single molecule level by the use of fluorescent probes has become one of the most promising approaches for understanding a variety of phenomena in living organisms. By applying techniques of fluorescence spectroscopy to labelled molecules a manifold of different parameters becomes accessible i.e. molecular dynamics, energy transfer, DNA fingerprinting, etc... can be monitored at

Signal Processing, 2004

Rare-earth-ion doped KY(WO 4 ) 2 (hereafter KYW) is a promising material for novel solidstate las... more Rare-earth-ion doped KY(WO 4 ) 2 (hereafter KYW) is a promising material for novel solidstate lasers . Low laser threshold, high efficiency, high output powers, and third-order nonlinear effects have stimulated research towards miniaturized thin-film waveguide lasers and amplifiers for future photonic devices. Active films can be fabricated by liquid-phase epitaxy (LPE), pulsed laser deposition, ion implantation, and diffusion bonding .

Microelectronic Engineering, 2006

The distribution of metal-precursors supplied via a gas injection system to the substrate inside ... more The distribution of metal-precursors supplied via a gas injection system to the substrate inside a focused electron beam (FEB) induced deposition system is investigated for the first time. The impinging precursor molecules are thermally decomposed using a heating stage. Resulting deposit thickness profiles obtained from [(PF 3 ) 2 RhCl] 2 , Co 2 (CO) 8 , and (hfac)CuVTMS precursors are determined optically by interference colors or by profilometry. FEB access to the precursor flux peak and the flux peak value itself depend on tube tilt and vertical tube distance to the substrate. Monte Carlo simulation match best the experiments when assuming molecular flow conditions.

Beilstein Journal of Nanotechnology, 2014

A thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking ... more A thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking full advantages of unique properties of each component. In this context, combining TiO 2 nanocrystals and carbon nanotubes (CNTs) offers enhanced photosensitivity and improved photocatalytic efficiency, which is key to achieving sustainable energy and preventing environmental pollution. Hence, it has aroused a tremendous research interest. This report surveys recent research on the topic of synthesis and characterization of the CNT-TiO 2 interface. In particular, atomic layer deposition (ALD) offers a good control of the size, crystallinity and morphology of TiO 2 on CNTs. Analytical transmission electron microscopy (TEM) techniques such as electron energy loss spectroscopy (EELS) in scanning transmission mode provides structural, chemical and electronic information with an unprecedented spatial resolution and increasingly superior energy resolution, and hence is a necessary tool to characterize the CNT-TiO 2 interface, as well as other technologically relevant CNT-metal/metal oxide material systems.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1999

We demonstrate the operation of bottom-emitting vertical cavity surface-emitting lasers ͑VCSELs͒ ... more We demonstrate the operation of bottom-emitting vertical cavity surface-emitting lasers ͑VCSELs͒ with linear mode polarization which is controlled in an arbitrary orientation by the use of patterned metallic mirrors on top of the VCSEL surface. The top mirror is made in the shape of a 200 nm pitch grating, composed of alternating high reflectivity ͑Au͒ and low reflectivity ͑Cr͒ metal lines, whose orientation determines the polarization of the laser mode. The gratings were fabricated by high-resolution ͑Ͻ50 nm͒ electron-beam lithography and lift-off technique, and were aligned with the other parts of the VCSEL structure ͑top electrode, ion-implanted zone͒ fabricated by conventional photolithography. Various types of mirror shapes and sizes were fabricated, including square and circular grating envelopes, as well as circular mirrors with an average ͑radial͒ Gaussian reflectivity.

Optics Letters, 2005

Baida and Van Labeke recently proposed a structure that exhibits a supertransmission of light thr... more Baida and Van Labeke recently proposed a structure that exhibits a supertransmission of light through an array of nanometric coaxial apertures in a metallic film that has been named an annular aperture array (AAA) [Opt. Commun. 209, 17 (2002); Phys. Rev. B 67, 155314 (2003); J. Microsc. 213, 140 ]. We present the first experimental study, to our knowledge, of an AAA structure in the visible region. For technological reasons, the structure under study does not produce a supertransmission of 80% as in Baida and Van Labeke [Opt. Commun. 209, 17 (2002)]. We built the nanostructure and experimentally recorded its

Nanotechnology, 2005

We report on the fabrication of two-dimensional arrays of nano-optical apertures in gold layers b... more We report on the fabrication of two-dimensional arrays of nano-optical apertures in gold layers by electron beam lithography (EBL) on a transparent glass substrate. 30 × 30 µm 2 large arrays of high aspect ratio sub-wavelength cylinders (400 nm diameter with period of 1.81 µm) and annular apertures (diameters 250/330 nm and 310/330 nm inner/outer with period of 600 nm) were patterned in a 750 nm thick resist layer using a high contrast negative tone resist. The resist structures show sharp and vertical edges after development. The 150 nm thick deposited gold layer ensures optical transmission of less than 1.1 × 10 −4 at 633 nm wavelength. White light based optical characterizations agreed with theory predictions and prove the good quality of the structures.