Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2001
ABSTRACT Defect transformations at low temperatures in ion implanted AlxGa1−xAs (0⩽x⩽1) ternary c... more ABSTRACT Defect transformations at low temperatures in ion implanted AlxGa1−xAs (0⩽x⩽1) ternary compounds were studied. Experiments consisted of ion implantation with 150 keV N or 200 keV Ar ions with different doses at temperatures between 18 and 77 K, and in situ RBS/channeling measurements at selected temperatures. An important recovery stage attributed to the defect mobility in the Ga(Al) sublattice was revealed near 280 K. For x>0.5 this stage was largely suppressed. Instead, a continuous damage recovery at low temperatures was observed. It was noticed that defect recombination can also be produced upon prolonged storage at the implantation temperature. For AlAs (x=1) the 280 K stage disappeared completely and only a small defect recovery at low temperatures was noticed. Upon N- or Ar-ion bombardment, after an incubation period, a sharp crystalline-to-amorphous transition appeared. The amorphization dose increases with increasing x and is a factor of 10 higher for x=0.96 than that for x=0. A further increase of the dose by a factor of 15 was required to amorphize AlAs (x=1).
ABSTRACT Transport studies of as-grown and proton-irradiated n-InN have been performed aiming at ... more ABSTRACT Transport studies of as-grown and proton-irradiated n-InN have been performed aiming at verification of the nature of localized donor states resonant with the InN conduction band. These resonant donor states (RDS) show a clear contribution to the electrical conduction in low electron concentration InN epitaxial layers. We used proton irradiation to increase the number of incorporated native point defects of donor character in InN layers. Then, the performed studies of pressure dependence of the Hall electron concentration clearly show no increase in the number of RDS in samples exposed to irradiation in spite of the increase in the conducting electron concentration.
Theory and Simulation in Physics for Materials Applications, 2020
This chapter describes the most important features of computational software called ‘McChasy’, wh... more This chapter describes the most important features of computational software called ‘McChasy’, which is a Monte Carlo (MC) simulation code developed for the evaluation of the Rutherford Backscattering Spectrometry data, in particular, recorded in the channeling mode (RBS/C). RBS/C is an experimental technique used in the analysis of defects in single crystals. Lattice distortions affect materials modified by ion beams or exposed to irradiation. Therefore, the analysis of damage in crystals is of high importance in materials science. Various types of defects can be created due to the interaction of ions with targets. However, RBS/C has different sensitivity to each of them so the analytical analysis of experimental data is hardly possible. MC simulations are a powerful tool used to overcome this limitation. The McChasy code simulates the movement of light ions in crystals. The software provides a fitting procedure of RBS/C spectra based on independent depth profiles of different defect types: interstitials, edge dislocations, substitutions, stacking faults or grain boundaries. The code works well not only with materials containing complex defects but also with heterostructures and superlattices. Recent improvements of the code include a unique approach of 3D-interaction between ions and target atoms. Application of the McChasy code in the analysis of crystal defects is described and possible ways of its further development are pointed out.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1999
ABSTRACT Defect recovery in GaAs and AlGaAs is principally governed by two annealing stages occur... more ABSTRACT Defect recovery in GaAs and AlGaAs is principally governed by two annealing stages occurring at 235 and 280 K that are attributed to the defect mobility in the Ga(Al) sublattice. To elucidate to what extent the defect clustering can suppress the damage recovery, GaAs single crystals and AlGaAs epitaxial layers were implanted at 77 K with 150 keV N- and Se-ions to fluences ranging from 5 × 1013 to 2 × 1014 at/cm2. Implanted crystals were analyzed in situ using the RBS/channeling technique. Successive measurements were performed during warming up of the sample to room temperature. For samples bombarded below the amorphisation threshold the defect content decreases rapidly between 200 and 295 K. The residual damage amounted to less than 50% of the initial damage. For crystals that were driven amorphous, the amorphized region remained unchanged upon warming up. Defect annealing occurred only in the tail region of the defect distribution.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013
ABSTRACT Damage formation in ion implanted InP is studied by quasi–in situ Rutherford backscatter... more ABSTRACT Damage formation in ion implanted InP is studied by quasi–in situ Rutherford backscattering spectrometry (RBS) in channelling configuration. Subsequent implantation steps are performed at 15 K each followed by immediate RBS analysis without changing the environment or the temperature of the sample. 30 keV He, 150 keV N and 350 keV Ca ions were applied. The depth distribution of damage is in good agreement with that calculated with the SRIM code. The evolution of damage at the maximum of the distribution as a function of the ion fluence is described assuming damage formation within single ion impacts and stimulated growth of damage when the collision cascades start to overlap with cross sections σd and σg, respectively. These cross sections are found to depend on the primary energies deposited in the displacement of lattice atoms and in electronic interactions calculated with the SRIM code. The obtained empirical formulas are capable to represent the experimental results for different III–V compounds implanted at 15 K with various ion species.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2015
ABSTRACT A semi-thick target method has been used to measure the stopping power for recoils produ... more ABSTRACT A semi-thick target method has been used to measure the stopping power for recoils produced in the 120Sn(14N, 5n)129La, 120Sn(11B, 4n)127Cs and 118Sn(11B, 4n)125Cs reactions by γ-ray lineshape analysis. The target quality and thickness (1.2 mg/cm2) were determined by the Rutherford backscattering spectrometry technique. Electronic and nuclear stopping-power parameters were determined for Cs and La ions in Sn and compared with parameters measured with the same method for Pm, Sm and Nd ions in Cd and I ions in Ag. A comparison with the LSS theory was made for the energy range below 0.2 MeV/nucleon, where the Bethe–Bloch formula has no application.
The stability of Au wire connections to n-SiC/Ti ohmic contacts and to n-SiC/Ni ohmic contacts wi... more The stability of Au wire connections to n-SiC/Ti ohmic contacts and to n-SiC/Ni ohmic contacts with top Au or Pt layers has been investigated. Long-term tests of the connections are performed in air at 400oC. Evaluation of electrical parameters, morphology and structure of the metallization as well as the strength of Au joint show stable Au wire bonds to the metallization with Ti-ohmic contacts.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2001
ABSTRACT Defect transformations at low temperatures in ion implanted AlxGa1−xAs (0⩽x⩽1) ternary c... more ABSTRACT Defect transformations at low temperatures in ion implanted AlxGa1−xAs (0⩽x⩽1) ternary compounds were studied. Experiments consisted of ion implantation with 150 keV N or 200 keV Ar ions with different doses at temperatures between 18 and 77 K, and in situ RBS/channeling measurements at selected temperatures. An important recovery stage attributed to the defect mobility in the Ga(Al) sublattice was revealed near 280 K. For x>0.5 this stage was largely suppressed. Instead, a continuous damage recovery at low temperatures was observed. It was noticed that defect recombination can also be produced upon prolonged storage at the implantation temperature. For AlAs (x=1) the 280 K stage disappeared completely and only a small defect recovery at low temperatures was noticed. Upon N- or Ar-ion bombardment, after an incubation period, a sharp crystalline-to-amorphous transition appeared. The amorphization dose increases with increasing x and is a factor of 10 higher for x=0.96 than that for x=0. A further increase of the dose by a factor of 15 was required to amorphize AlAs (x=1).
ABSTRACT Transport studies of as-grown and proton-irradiated n-InN have been performed aiming at ... more ABSTRACT Transport studies of as-grown and proton-irradiated n-InN have been performed aiming at verification of the nature of localized donor states resonant with the InN conduction band. These resonant donor states (RDS) show a clear contribution to the electrical conduction in low electron concentration InN epitaxial layers. We used proton irradiation to increase the number of incorporated native point defects of donor character in InN layers. Then, the performed studies of pressure dependence of the Hall electron concentration clearly show no increase in the number of RDS in samples exposed to irradiation in spite of the increase in the conducting electron concentration.
Theory and Simulation in Physics for Materials Applications, 2020
This chapter describes the most important features of computational software called ‘McChasy’, wh... more This chapter describes the most important features of computational software called ‘McChasy’, which is a Monte Carlo (MC) simulation code developed for the evaluation of the Rutherford Backscattering Spectrometry data, in particular, recorded in the channeling mode (RBS/C). RBS/C is an experimental technique used in the analysis of defects in single crystals. Lattice distortions affect materials modified by ion beams or exposed to irradiation. Therefore, the analysis of damage in crystals is of high importance in materials science. Various types of defects can be created due to the interaction of ions with targets. However, RBS/C has different sensitivity to each of them so the analytical analysis of experimental data is hardly possible. MC simulations are a powerful tool used to overcome this limitation. The McChasy code simulates the movement of light ions in crystals. The software provides a fitting procedure of RBS/C spectra based on independent depth profiles of different defect types: interstitials, edge dislocations, substitutions, stacking faults or grain boundaries. The code works well not only with materials containing complex defects but also with heterostructures and superlattices. Recent improvements of the code include a unique approach of 3D-interaction between ions and target atoms. Application of the McChasy code in the analysis of crystal defects is described and possible ways of its further development are pointed out.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1999
ABSTRACT Defect recovery in GaAs and AlGaAs is principally governed by two annealing stages occur... more ABSTRACT Defect recovery in GaAs and AlGaAs is principally governed by two annealing stages occurring at 235 and 280 K that are attributed to the defect mobility in the Ga(Al) sublattice. To elucidate to what extent the defect clustering can suppress the damage recovery, GaAs single crystals and AlGaAs epitaxial layers were implanted at 77 K with 150 keV N- and Se-ions to fluences ranging from 5 × 1013 to 2 × 1014 at/cm2. Implanted crystals were analyzed in situ using the RBS/channeling technique. Successive measurements were performed during warming up of the sample to room temperature. For samples bombarded below the amorphisation threshold the defect content decreases rapidly between 200 and 295 K. The residual damage amounted to less than 50% of the initial damage. For crystals that were driven amorphous, the amorphized region remained unchanged upon warming up. Defect annealing occurred only in the tail region of the defect distribution.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013
ABSTRACT Damage formation in ion implanted InP is studied by quasi–in situ Rutherford backscatter... more ABSTRACT Damage formation in ion implanted InP is studied by quasi–in situ Rutherford backscattering spectrometry (RBS) in channelling configuration. Subsequent implantation steps are performed at 15 K each followed by immediate RBS analysis without changing the environment or the temperature of the sample. 30 keV He, 150 keV N and 350 keV Ca ions were applied. The depth distribution of damage is in good agreement with that calculated with the SRIM code. The evolution of damage at the maximum of the distribution as a function of the ion fluence is described assuming damage formation within single ion impacts and stimulated growth of damage when the collision cascades start to overlap with cross sections σd and σg, respectively. These cross sections are found to depend on the primary energies deposited in the displacement of lattice atoms and in electronic interactions calculated with the SRIM code. The obtained empirical formulas are capable to represent the experimental results for different III–V compounds implanted at 15 K with various ion species.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2015
ABSTRACT A semi-thick target method has been used to measure the stopping power for recoils produ... more ABSTRACT A semi-thick target method has been used to measure the stopping power for recoils produced in the 120Sn(14N, 5n)129La, 120Sn(11B, 4n)127Cs and 118Sn(11B, 4n)125Cs reactions by γ-ray lineshape analysis. The target quality and thickness (1.2 mg/cm2) were determined by the Rutherford backscattering spectrometry technique. Electronic and nuclear stopping-power parameters were determined for Cs and La ions in Sn and compared with parameters measured with the same method for Pm, Sm and Nd ions in Cd and I ions in Ag. A comparison with the LSS theory was made for the energy range below 0.2 MeV/nucleon, where the Bethe–Bloch formula has no application.
The stability of Au wire connections to n-SiC/Ti ohmic contacts and to n-SiC/Ni ohmic contacts wi... more The stability of Au wire connections to n-SiC/Ti ohmic contacts and to n-SiC/Ni ohmic contacts with top Au or Pt layers has been investigated. Long-term tests of the connections are performed in air at 400oC. Evaluation of electrical parameters, morphology and structure of the metallization as well as the strength of Au joint show stable Au wire bonds to the metallization with Ti-ohmic contacts.
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