... Rastislav Kosiba ∗ ∗∗ — Gernot Ecke ∗ — Jozef Liday ∗∗ Juraj Breza ∗∗ — Oliver Ambacher ∗ ...... more ... Rastislav Kosiba ∗ ∗∗ — Gernot Ecke ∗ — Jozef Liday ∗∗ Juraj Breza ∗∗ — Oliver Ambacher ∗ ... The samples were transferred without any pre-treatment into the UHV chamber of the Riber ASC 2000 Auger electron spectrometer. ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2002
Surface analytical methods like AES, XPS or SIMS mostly use ion beam sputtering as a tool for dep... more Surface analytical methods like AES, XPS or SIMS mostly use ion beam sputtering as a tool for depth profile analysis. The depth resolution of sputter depth profiles depends strongly on the ion–solid interactions. On this background, Monte Carlo (MC) simulations of sputter depth profiles have been carried out by means of T-DYN. After introducing the simulation model special emphasis has been paid to the input parameters such as the surface binding energy, bulk binding energy, cut-off and displacement energy, atomic density and their influence on the simulation results. A silicon carbide layer on Si and a Pt delta-doped silicon serve as targets for simulation tests. Although the influence of the surface binding energy is mainly important for the sputtering yield, this parameter together with the cut-off energy prove to be important for the resultant depth profiles and their depth resolution. The uniformity of the atomic density over the whole target in T-DYN limits the applicability of this simulation code.
Sputtering yields of α-SiC crystals in the energy range of argon ions from 1 to 2.5 keV as a func... more Sputtering yields of α-SiC crystals in the energy range of argon ions from 1 to 2.5 keV as a function of substrate temperature were determined. For a normal incident beam the sputtering yield was in the range 0.45 – 0.71 for acceleration voltages of 1–2.6 keV. The temperature dependence of the sputtering yield was determined at 2 keV in the temperature range 20–1000 °C. A drop in sputtering yield was observed between 400 °C and 700 °C. Auger electron spectroscopy studies and computer simulation of Ar+ sputtering as a function of the ion energy at room temperature showed changes in composition under argon sputtering, which were due to preferential sputtering of silicon. At room temperature sputtering led to the formation of a thin amorphized layer on the surface, observed by reflection high energy electron diffraction. At a substrate temperature of 200 °C a partial phase transition of the type GH → 3C was obtained, whereas at 400 °C a partial transition of the type 6H → 15R occurred. At higher substrate temperatures no changes in the polytype structure were observed. However, increasing temperatures led to a decrease and at higher temperatures to elimination of the amorphized fraction at the silicon carbide surface.
An electron cyclotron resonance plasma source was used for the deposition of aluminium nitride (A... more An electron cyclotron resonance plasma source was used for the deposition of aluminium nitride (AlN). AlN films were grown using trimethyl aluminium in hydrogen as carrier gas and nitrogen or ammonia as a nitrogen source onto silicon, glass and steel substrates. The deposition temperature was ranging from 200 to 600°C, the microwave power was varied from 250 to 400 W and the operation pressure was (1–4) × 10−3 mbar. Atomic composition of the samples was investigated by Auger electron spectrometry and Fourier transform IR spectrometry and mechanical properties were investigated by a dynamic force-penetration method and scratch test. The influence of the deposition parameters on the structure and hardness were investigated. The incorporation of oxygen into the AlN films after the deposition is caused by diffusion of water along the grain boundaries of textured layers. Universal hardness of 10 000 N mm−2 and critical loads up to 42 N were found for AlN coatings on steel substrates.
... mass spectrometry (SIMS). The sputter depth profiling in conjunction with AES was carried out... more ... mass spectrometry (SIMS). The sputter depth profiling in conjunction with AES was carried out with a Riber ASC2000 using 1 keV Ar+ ions impinging onto the surface under 60° with respect to the surface normal. The SIMS spectra ...
Journal of Materials Science: Materials in Electronics, 2008
ABSTRACT In this study we investigated the effect of a NiO x layer on the electrical properties o... more ABSTRACT In this study we investigated the effect of a NiO x layer on the electrical properties of oxidized Au/NiO x /p-GaN ohmic contacts. Au/NiO x layers with a small concentration of oxygen in NiO x were deposited on p-GaN by reactive DC magnetron sputtering and annealed in a mixture of O2+N2, and in N2. Auger electron spectroscopy (AES) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) depth profiling in combination with transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE SEM) and the circular transmission line method (CTLM) of contact resistance measurements of the contact structure with low content of oxygen in the NiO x layer have been used to explain the reduction of the contact resistance as a result of its anneal treatment. It has been found that creation of a metal/p-NiO/p-GaN contact structure due to annealing of the Au/NiO x /p-GaN structure in either N2 or O2+N2 is the main mechanism that is responsible for the ohmic nature of the system. However, lowering of the contact resistance is similarly affected also by Ga atoms leaving the vacancies at the metal/p-GaN interface after diffusion of Ga into the metallic layer. The effect of various ways of cleaning the p-GaN surface prior to metallization on the contact resistance has also been investigated.
ABSTRACT Anion–cation radical formation in solid films of M3EH-PPV blended with C60-PCBM, C120-O-... more ABSTRACT Anion–cation radical formation in solid films of M3EH-PPV blended with C60-PCBM, C120-O-PCBM and C60-MDHE, C120-O-MDHE under diode laser (532 nm) and Xe-lamp light excitation studied by means of X,W-band at temperatures 30–80 K is reported. Subsequent high frequency W-band ESR data demonstrate the reproducible, but variable effect of appreciable dispersion (D) contribution in the ESR spectral line for the di-fullerene anion radicals. It is suggested that the increase of the D part relative to the absorption (A) in the summarized ESR absorption line in blends with difullerenes is caused by the higher value of difullerene medium conductivity. The obtained data are quantitatively discussed by the D/A ∼ F(d/δ) functional dependence in approach of plane film geometry, where d is the film thickness and δ is the skin-depth. The influence of ν-dependent δ at D/A value has been checked using X-band LESR.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2004
... The surface had an average rms roughness of 7.1 nm estimated by atomic force microscopy (AFM)... more ... The surface had an average rms roughness of 7.1 nm estimated by atomic force microscopy (AFM). The sputter depth profiling procedures were carried out in the Auger spectrometer Riber ASC 2000 equipped with a differentially pumped ion gun VG X5. ...
... epitaxy. The Si etch experiments were carried out on the bare substrate material used for the... more ... epitaxy. The Si etch experiments were carried out on the bare substrate material used for the 3C-SiC growth. The used equipment consists of a Roth & Rau ECR source mounted on a PLS 500 system from Balzers AG. The set ...
... Rastislav Kosiba ∗ ∗∗ — Gernot Ecke ∗ — Jozef Liday ∗∗ Juraj Breza ∗∗ — Oliver Ambacher ∗ ...... more ... Rastislav Kosiba ∗ ∗∗ — Gernot Ecke ∗ — Jozef Liday ∗∗ Juraj Breza ∗∗ — Oliver Ambacher ∗ ... The samples were transferred without any pre-treatment into the UHV chamber of the Riber ASC 2000 Auger electron spectrometer. ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2002
Surface analytical methods like AES, XPS or SIMS mostly use ion beam sputtering as a tool for dep... more Surface analytical methods like AES, XPS or SIMS mostly use ion beam sputtering as a tool for depth profile analysis. The depth resolution of sputter depth profiles depends strongly on the ion–solid interactions. On this background, Monte Carlo (MC) simulations of sputter depth profiles have been carried out by means of T-DYN. After introducing the simulation model special emphasis has been paid to the input parameters such as the surface binding energy, bulk binding energy, cut-off and displacement energy, atomic density and their influence on the simulation results. A silicon carbide layer on Si and a Pt delta-doped silicon serve as targets for simulation tests. Although the influence of the surface binding energy is mainly important for the sputtering yield, this parameter together with the cut-off energy prove to be important for the resultant depth profiles and their depth resolution. The uniformity of the atomic density over the whole target in T-DYN limits the applicability of this simulation code.
Sputtering yields of α-SiC crystals in the energy range of argon ions from 1 to 2.5 keV as a func... more Sputtering yields of α-SiC crystals in the energy range of argon ions from 1 to 2.5 keV as a function of substrate temperature were determined. For a normal incident beam the sputtering yield was in the range 0.45 – 0.71 for acceleration voltages of 1–2.6 keV. The temperature dependence of the sputtering yield was determined at 2 keV in the temperature range 20–1000 °C. A drop in sputtering yield was observed between 400 °C and 700 °C. Auger electron spectroscopy studies and computer simulation of Ar+ sputtering as a function of the ion energy at room temperature showed changes in composition under argon sputtering, which were due to preferential sputtering of silicon. At room temperature sputtering led to the formation of a thin amorphized layer on the surface, observed by reflection high energy electron diffraction. At a substrate temperature of 200 °C a partial phase transition of the type GH → 3C was obtained, whereas at 400 °C a partial transition of the type 6H → 15R occurred. At higher substrate temperatures no changes in the polytype structure were observed. However, increasing temperatures led to a decrease and at higher temperatures to elimination of the amorphized fraction at the silicon carbide surface.
An electron cyclotron resonance plasma source was used for the deposition of aluminium nitride (A... more An electron cyclotron resonance plasma source was used for the deposition of aluminium nitride (AlN). AlN films were grown using trimethyl aluminium in hydrogen as carrier gas and nitrogen or ammonia as a nitrogen source onto silicon, glass and steel substrates. The deposition temperature was ranging from 200 to 600°C, the microwave power was varied from 250 to 400 W and the operation pressure was (1–4) × 10−3 mbar. Atomic composition of the samples was investigated by Auger electron spectrometry and Fourier transform IR spectrometry and mechanical properties were investigated by a dynamic force-penetration method and scratch test. The influence of the deposition parameters on the structure and hardness were investigated. The incorporation of oxygen into the AlN films after the deposition is caused by diffusion of water along the grain boundaries of textured layers. Universal hardness of 10 000 N mm−2 and critical loads up to 42 N were found for AlN coatings on steel substrates.
... mass spectrometry (SIMS). The sputter depth profiling in conjunction with AES was carried out... more ... mass spectrometry (SIMS). The sputter depth profiling in conjunction with AES was carried out with a Riber ASC2000 using 1 keV Ar+ ions impinging onto the surface under 60° with respect to the surface normal. The SIMS spectra ...
Journal of Materials Science: Materials in Electronics, 2008
ABSTRACT In this study we investigated the effect of a NiO x layer on the electrical properties o... more ABSTRACT In this study we investigated the effect of a NiO x layer on the electrical properties of oxidized Au/NiO x /p-GaN ohmic contacts. Au/NiO x layers with a small concentration of oxygen in NiO x were deposited on p-GaN by reactive DC magnetron sputtering and annealed in a mixture of O2+N2, and in N2. Auger electron spectroscopy (AES) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) depth profiling in combination with transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE SEM) and the circular transmission line method (CTLM) of contact resistance measurements of the contact structure with low content of oxygen in the NiO x layer have been used to explain the reduction of the contact resistance as a result of its anneal treatment. It has been found that creation of a metal/p-NiO/p-GaN contact structure due to annealing of the Au/NiO x /p-GaN structure in either N2 or O2+N2 is the main mechanism that is responsible for the ohmic nature of the system. However, lowering of the contact resistance is similarly affected also by Ga atoms leaving the vacancies at the metal/p-GaN interface after diffusion of Ga into the metallic layer. The effect of various ways of cleaning the p-GaN surface prior to metallization on the contact resistance has also been investigated.
ABSTRACT Anion–cation radical formation in solid films of M3EH-PPV blended with C60-PCBM, C120-O-... more ABSTRACT Anion–cation radical formation in solid films of M3EH-PPV blended with C60-PCBM, C120-O-PCBM and C60-MDHE, C120-O-MDHE under diode laser (532 nm) and Xe-lamp light excitation studied by means of X,W-band at temperatures 30–80 K is reported. Subsequent high frequency W-band ESR data demonstrate the reproducible, but variable effect of appreciable dispersion (D) contribution in the ESR spectral line for the di-fullerene anion radicals. It is suggested that the increase of the D part relative to the absorption (A) in the summarized ESR absorption line in blends with difullerenes is caused by the higher value of difullerene medium conductivity. The obtained data are quantitatively discussed by the D/A ∼ F(d/δ) functional dependence in approach of plane film geometry, where d is the film thickness and δ is the skin-depth. The influence of ν-dependent δ at D/A value has been checked using X-band LESR.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2004
... The surface had an average rms roughness of 7.1 nm estimated by atomic force microscopy (AFM)... more ... The surface had an average rms roughness of 7.1 nm estimated by atomic force microscopy (AFM). The sputter depth profiling procedures were carried out in the Auger spectrometer Riber ASC 2000 equipped with a differentially pumped ion gun VG X5. ...
... epitaxy. The Si etch experiments were carried out on the bare substrate material used for the... more ... epitaxy. The Si etch experiments were carried out on the bare substrate material used for the 3C-SiC growth. The used equipment consists of a Roth & Rau ECR source mounted on a PLS 500 system from Balzers AG. The set ...
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