"Etchability" of ion tracks in Si02/Si and Si3N4/Si thin layers

We have calculated radii and lifetime of the molten regions or the regions heated to the melting point that are formed under irradiation of amorphous SiO2 and Si3N4 with swift ions. A computer simulation was carried out on the base of thermal spike model. A comparison of calculated track parameters with ion track etching data have been made for these materials. It is shown that an existence of molten region along swift ion trajectory may be a criterion for a track “etchability” in the case of SiO2. In the same conditions of chemical etching diameter of etched tracks in SiO2 is proportional to the radius and lifetime of the molten region. This information is important for a correct choice of irradiation regime aimed at preparation of nanoporous layers with high pore density ( 10 10 cm-2). When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2087

Structural Peculiarities of A3B5 Nanocrystals Created in Si by Ion-Beam Synthesis

We reported the structure peculiarities of nanocrystals formed in Si by means of high-fluence implantation at 25 and 500 °С followed by rapid thermal annealing (RTA). The structure of implanted samples has been investigated by means of transmission electron microscopy (TEM). The crystalline nature of the precipitates is proved by the Moiré fringe patterns presence in the TEM images. The Moiré fringe distance (Moiré period) is equal of 1.8 nm for small precipitates. This experimental value coincides with the calculated one for crystalline InAs. It is noted a Moiré period increasing in the case of large precipitates. We suppose that this feature is a result of surplus As or In atoms embedded in precipitates. One can see an interesting effect – “glowng” of nanocrystal/Si interfaces at the dark-field images of implanted and annealed samples. We ascribe this effect to a presence of misfit dislocation networks at the InAs/Si interfaces generated as a result of strain relaxation in highly mismatched InAs/Si system. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3543

Effects of annealing regims on the structural and optical properties of inas and gasb nanocryctals created by ion-beam synthesis in Si matrix

We have studied the ion-beam synthesis of InAs and GaSb nanocrystals in Si by high-fluence implantation of (As+In) and (Ga+Sb) ions followed a thermal annealing. In order to characterize the implanted samples Rutherford backscattering spectrometry in combination with the channelling (RBS/C), transmission electron microscopy (TEM), Raman spectrometry (RS) and low-temperature photoluminescence (PL) techniques were employed. It was demonstrated that by introducing getter, varying the ion implantation temperature, ion fluences and post-implantation annealing duration and temperature it is possible to form InAs and GaSb nanocrystals in the range of sizes of (2 – 80) nm and create different types of secondary defects distribution. RS results confirm the crystalline state of the clusters in the silicon matrix after high-fluence implantation of heavy (As+In) and (Ga+Sb) ions. Significant redistribution of implanted species has been revealed after “hot” implantation and post-implantation annealing. We have suggested that it is caused by non-equilibrium diffusion. A broad band in the spectral region of 0.7 – 1.1 eV is detected in the photoluminescence spectra of the samples. The nature of this PL band is discussed.We have studied the ion-beam synthesis of InAs and GaSb nanocrystals in Si by high-fluence implantation of (As+In) and (Ga+Sb) ions followed a thermal annealing. In order to characterize the implanted samples Rutherford backscattering spectrometry in combination with the channelling (RBS/C), transmission electron microscopy (TEM), Raman spectrometry (RS) and low-temperature photoluminescence (PL) techniques were employed. It was demonstrated that by introducing getter, varying the ion implantation temperature, ion fluences and post-implantation annealing duration and temperature it is possible to form InAs and GaSb nanocrystals in the range of sizes of (2 – 80) nm and create different types of secondary defects distribution. RS results confirm the crystalline state of the clusters in the silicon matrix after high-fluence implantation of heavy (As+In) and (Ga+Sb) ions. Significant redistribution of implanted species has been revealed after “hot” implantation and post-implantation annealing. We have suggested that it is caused by non-equilibrium diffusion. A broad band in the spectral region of 0.7 – 1.1 eV is detected in the photoluminescence spectra of the samples. The nature of this PL band is discussed. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2083

Strong Room-Temperature Photoluminescence of Si-rich and N-rich Silicon-Nitride Films

Si-rich and N-rich silicon nitride films were deposited at low temperature 300 °C by using plasmaenhanced chemical vapor deposition (PECVD). The optical and structural properties of these films have been investigated by ellipsometry, Rutherford backscattering (RBS), transmission electron microscopy (TEM), Raman spectroscopy (RS) and photoluminescence (PL). The formation of silicon clusters in both Sirich and N-rich silicon nitride films after annealing at 900 °C and 1000 °C for hour in N2 ambient has been shown by TEM. Dependency of PL spectra on stoichiometry and post-annealing temperature was analyzed. The contribution of Si and N-related defects in emitting properties of Si-rich and N-rich SiNx has been discussed. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3516

Phase Transformation in the Annealed Si-Rich SiNx Films Studied by Raman Scattering

The Si-rich SiNx films were deposited on Si wafers by low pressure chemical vapor deposition (LPCVD) technique followed by annealing at (800 – 1200) °C. Excess (overstoichiometric) Si content in nitride films was calculated from Rutherford backscattering data (RBS). Existence and evolution of Si nanoclusters from amorphous to crystalline ones under high temperature treatment were confirmed by Raman scattering (RS) measurements. Amorphous Si clusters have already existed in as-deposited SiNx films. Thermal treatment results in the formation of additional amorphous nanoclusters and in their crystallization with anneal temperature increasing. Nitride films annealed at 1200 °C contain crystalline Si clusters only. It was revealed a dependence of Si wafer’s Raman scattering intensity on the temperature of SiNx/Si structures annealing. This information in combination with RBS data has allowed us to estimate and distinguish the excess silicon aggregated in clusters and the excess silicon distributed over the silicon nitride matrix

Structure and optical properties of silicon layers with GaSb nanocrystals created by ion-beam synthesis

We have studied the ion-beam synthesis of GaSb nanocrystals in Si by high-fluence implantation of Sb and Ga ions followed by thermal annealing. RBS, TEM/TED, RS, and photoluminescence (PL) were employed to characterize the implanted layers. It was found that the nanocrystals size increases from 5 to 60 nm in the samples annealed at 900 8Cup to 20–90 nm in the samples annealed at 1100 8C. An existence of significant mechanical stresses within implanted layers has been detected. The stress values have been calculated from the shift of the Si first order Raman band. For the samples annealed at 900 8C a broad band in the spectral region of about 0.75–1.05 eV is detected in the PL spectra. The nature of this PL band is discussed

Nanocrystal- and Dislocation-Related Luminescence in Si Matrix with InAs Nanocrystals

We have studied the influence of ion implantation and post-implantation annealing regimes on the structural and optical properties of silicon matrix with ion-beam synthesized InAs nanocrystals. (100) Si wafers were implanted at 25 and 500 ±C, subsequently with high fluences of As and In ions. After implantation the samples were processed by furnace and rapid thermal annealing at 900, 950 and 1050 ±C. A part of the samples implanted at 25 ±C was additionally exposed to H+2 ions (100 keV, 1.2 × 1016 cm−2 in terms of atomic hydrogen). This procedure was performed to obtain an internal getter. In order to characterize the implanted samples transmission electron microscopy and low-temperature photoluminescence techniques were employed. It was demonstrated that by introducing getter, varying the ion implantation temperature, ion fluences and post-implantation annealing duration, and temperature it is possible to form InAs nanocrystals in the range of sizes of 2–80 nm and create various concentration and distribution of di˙erent types of secondary defects. The last ones cause in turn the appearance in photoluminescence spectra dislocation-related D1, D2 and D4 lines at 0.807, 0.870 and 0.997 eV, respectively

"Etchability" of ion tracks in Si02/Si and Si3N4/Si thin layers

We have calculated radii and lifetime of the molten regions or the regions heated to the melting point that are formed under irradiation of amorphous SiO2 and Si3N4 with swift ions. A computer simulation was carried out on the base of thermal spike model. A comparison of calculated track parameters with ion track etching data have been made for these materials. It is shown that an existence of molten region along swift ion trajectory may be a criterion for a track “etchability” in the case of SiO2. In the same conditions of chemical etching diameter of etched tracks in SiO2 is proportional to the radius and lifetime of the molten region. This information is important for a correct choice of irradiation regime aimed at preparation of nanoporous layers with high pore density ( 10 10 cm-2). When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2087