D. Żymierska

X-ray diffraction and Raman scattering study of near-surface structure perfection of GaAs single crystals after anisotropic etching

Microrelief was developed on the surface of high quality GaAs single crystals by means of wet anisotropic etching. The surface relief characteristics and structure perfection of subsurface layer were studied by profilometric, optical reflection, Raman scattering, X-ray, and reflection high-energy electron diffraction methods.

Recrystallisation and dopant diffusion in amorphised germanium layers upon pulsed laser annealing

Abstract In the present paper the results of investigations of the recrystallisation process in amorphous Ge near-surface layers induced by laser annealing are reported. Amorphised layers were created by implantation of Ge single crystal with 150 keV Sn ions at a dose 1×10 16 cm −2 . Structural changes and redistribution of dopants were caused in irradiated materials by a single nanosecond laser pulse. For a study of the near-surface layer structure before and after laser annealing, the reflection high-energy electron diffraction technique was applied. Dopant diffusion was investigated by means of secondary ion mass spectrometry. Changes for polycrystalline of the near-surface layer structure amorphised by Sn implantation, occurred independently of the phase transitions and of the dopant concentration (0–8%).

Extended defect structure induced by pulsed laser annealing in Ge implanted Si crystal

The study of extended defects structure induced by the pulsed nanosecond radiation of an excimer laser with different energy density in Si single crystal implanted with Ge ions. Numerical calculations were done to determine the optimal value of the laser energy density causing the epitaxial recrystallization from the melt on a crystal substrate. The RBS were performed to study the near-surface structure of the different areas of the sample. The surface morphology was observed using the interference-polarizing microscope. Through the application of the section X-ray topography we have observed the crystal lattice deformation caused by laser annealing.

Pulsed laser annealing of Sn-implanted Si single crystal

A very disturbed near-surface layer was formed by Sn-ion implantation in a Si single crystal. For crystal lattice reconstruction of this layer and for change of the dopant distribution pulsed laser annealing was applied. In order to determine the optimal value of the energy density of laser pulse numerical calculations were performed. The experiments carried out by means of reflection high-energy electron diffraction and by Rutherford backscattering have shown that laser annealing caused the formation of the epitaxial Si1−xSnx layer. A good crystal quality of this layer, comparable with the quality of the single crystal Si matrix, as well as a good substitutional location of the Sn dopant atoms were obtained for the laser beam energy density value equal to the calculated optimal one.

Nanostructure of near-surface Si layers formed by implantation and pulsed laser annealing

Abstract A Si single crystal was implanted with a 5·10 15 cm −2 dose of 80 keV Si ions. We report the results of experimental and theoretical investigations of the structural changes induced by ultraviolet laser pulse in this crystal. The structural changes in the near-surface region were examined by means of reflection high-energy electron diffraction, Rutherford backscattering and interference-polarizing Nomarski microscopy. Numerical calculations of transient temperature profiles in the irradiated target were performed in order to evaluate the threshold and the optimal value of the radiation energy density, and to determine the temperature profiles in the annealed region. The obtained results were compared with previous findings of a defect structure in a laser annealed Si crystal matrix implanted with Ge ions. The formation of an extended defect structure on the surface of the annealed areas where melting and solidification occur was observed. The creation of this structure is a result of the relaxation of stresses caused by inhomogeneous heating and inhomogeneous cooling of the melted near-surface layer and it is independent of the introduced dopant.

Studies of the near-surface layers of silicon crystals implanted with fast ions

Abstract The near-surface layers of dislocation free silicon crystals implanted with 4 MeV/u oxygen and neon ions were investigated. The following methods: X-ray diffraction and reflectometry, reflection high-energy electron diffraction and Nomarski optical microscopy were used. The fine structural changes induced by irradiation were observed. For silicon crystal implanted with neon ions the increase of the lattice parameter and a disturbance of crystal structure were detected, whereas for silicon crystal bombarded with oxygen ions postimplantation defects on the surface were observed. For both cases the increase in the surface roughness was shown.

Comparative studies of Si single crystal surface disorder by using various methods of electromagnetic wave scattering

Silicon surface roughness characterization using electromagnetic wave scattering (from X-ray to infrared range) together with profilometer and AFM measurements are performed. The dependence of relief characterisation accuracy on the wavelength of the used source is analyzed. The comparison of both local (profilometer, AFM) and statistical data (grazing X-ray scattering, optical specular reflectance, multi-angle-of-incidence (MAI)-ellipsometry) is carried out.

Structural changes induced by implantation with 3 MeV/amu nitrogen ions in GaAs single crystals

The paper is a study of the microstructure of as grown semiconducting and semi-insulating GaAs crystals, as well as of fine structural changes induced in both materials by the implantation with a 5×1014 cm−2 dose of 3 MeV/amu nitrogen ions. X-ray measurements were carried out by means of a high-resolution diffractometer. The rocking curves of two as-grown GaAs samples studied are symmetrical. The rocking curve measured for the implanted semi-insulating crystal is broadened, while that for the implanted semiconducting crystal reveals a diffused subsidiary peak on the low angle side of the main maximum, indicating the presence of tensile stresses in the damaged layer at a depth of the mean ion range. The mathematical analysis of the reciprocal space maps gives a quantitative description of the experimental results.