M. F. Galyautdinov

Formation of periodic diffraction structures at semiconductor surfaces for studying the dynamics of photoinduced phase transitions

New methods for the formation of measuring periodic diffraction structures at silicon surfaces are proposed and tested. The one-dimensional grating is formed at a surface of implanted silicon by nanosecond laser annealing in the regime of interference of two crossed beams. The two-dimensional grating is formed at the surface of single-crystal silicon by implantation through a special periodic mask. Diffraction gratings formed are amplitude gratings because their periodically alternating fragments differ only in the reflection coefficient. The amplitude gratings were transformed into phase gratings by irradiation by pulses of incoherent light in the regime of local melting. A noticeable increase in the diffraction efficiency is found in this case, which allows these gratings to be used to study the dynamics of various phase transitions induced by high-power incoherent light pulses in implanted silicon.

Formation of a periodic diffractive structure based on poly(methyl methacrylate) with ion-implanted silver nanoparticles

We propose to form optical diffractive elements on the surface of poly(methyl methacrylate) (PMMA) by implanting the polymer with silver ions (E = 30 keV; D = 5.0 × 1014 to 1.5 × 1017 ion/cm2; I = 2 μA/cm2) through a nickel grid (mask). Ion implantation leads to the nucleation and growth of silver nanoparticles in unmasked regions of the polymer. The formation of periodic surface microstructures during local sputtering of the polymer by incident ions was monitored using an optical microscope. The diffraction efficiency of obtained gratings is demonstrated under conditions of their probing with semiconductor laser radiation in the visible spectral range.

The formation of periodic diffractive plasmonic nanostructures with implanted copper nanoparticles by local ion etching of silica glass

Silica glass was subjected to a low-energy implantation with 40-keV Cu+ ions at a dose of 7.5 × 1016 ions/cm2 and an ion-beam current density of 5 μA/cm2 through a surface metal-wire mask with square holes of ∼40 μm. The formation of copper nanoparticles in the glass was determined from the occurrence of characteristic plasmon optical absorption and through the detection of particles using an atomic force micro- scope. The formation of periodic surface microstructures via the local etching of silica glass during implantation was observed using a scanning electron microscope. The operating efficiency of the diffractive optical plasmonic element based on silica glass microstructures with metallic copper nanoparticles was shown during its sounding by the emission of a helium-neon laser.

THE DYNAMICS OF RECRYSTALLIZATION AND MELTING OF IMPLANTED SILICON AT IRRADIATION BY POWERFUL LIGHT PULSES

Abstract One of the effects observed in the irradiation of semiconductors by powerful pulses of coherent and incoherent light sources in the range of durations from 0.2 ms to 10 s is the effect of anisotropic local melting. It allows valuable physical information on semiconductor properties and processes occurring in the sample during and after pulse irradiation to be obtained. Here the dynamics of anisotropic local melting of implanted silicon for different regimes of light pulses is investigated. The nucleation and growth of local regions of melting (LRM) during the light irradiation was detected by a high-speed camera. The time dependencies of the quantity and sizes of LRMs were dynamically observed for the first time. Diffraction gratings were formed using ion implantation and the effect of local melting. The dynamics of diffraction during and after the light pulse irradiation were studied. The results allow the specification of the mechanism of the effect of anisotropic local melting, and the optimization of the regimes of pulse annealing of implanted semiconductors and the regimes of formation of submicron dopant layers by rapid thermal diffusion from spin-on sources.

Formation of a two-dimensional periodic structure of local melting regions on a silicon surface upon pulsed light irradiation

The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures is discussed.

A diffraction grating created in diamond substrate by boron ion implantation

This work is devoted to new method of manufacturing of diffractive optical elements (gratings). A grating was formed in a diamond substrate by implantation with boron ions through a mask. Ion implantation led to the graphitization of diamond in unmasked regions and resulted in swelling of the irradiated layer. The formation of periodic graphitized surface microstructures on the diamond substrate was confirmed by optical, electron, and atomic force microscopy. The efficiency of operation of the obtained diffractive optical element was demonstrated by probing with He–Ne laser radiation.

Development of the technique of laser diagnostics of solids under pulsed optical irradiation

A technique based on the recording of a Fraunhofer diffraction pattern and allowing studies of structural and phase transitions in an ion-implantion-doped semiconductor layer with a high time resolution simultaneously with sample-temperature measurements is described. For this purpose, two measuring diffraction gratings—phase and amplitude—are preliminarily formed on the surface of a silicon plate. Solid-phase recrystallization and melting processes were studied using the kinetics of disappearance and appearance of diffraction peaks from the amplitude grating. The sample temperature was monitored by the deviation of the diffraction angle of a probing laser beam from the phase diffraction grating caused by a change in the grating period resulting from its thermal expansion.

Dynamic thermometry of a solid via optical diffraction method at pulsed irradiation

A method for the fast measurement of the temperature of solids under the action of a high-power light pulse is proposed and demonstrated. This method is based on the application of the Fraunhofer diffraction and is implemented for silicon samples heated to melting temperatures Tmelt = 1412°C by a high-power light pulse. The current silicon temperature was determined by measuring the varying diffraction angle of the probing laser beam. The diffraction angle was varied over time because the period of the diffraction grating increased as a result of the dynamic thermal expansion of the crystal. An initial grating was formed on the surface of the silicon plate with a period of d = 4 µm. The radiation beam of a He-Ne laser with λ = 0.6328 µm was used as the probing beam; the measured signal was recorded in the pair of symmetric fifth-order diffraction maxima.

In situ investigation of phase transitions of implanted silicon at powerful light irradiation

Abstract The in situ investigations of anisotropic local melting of implanted and monocrystalline silicon during irradiation by powerful light pulses using a high-speed camera are presented. The methods of formation of special diffraction gratings are presented. The features of application of the gratings for the in situ investigation of structural and phase transitions of implanted silicon are discussed. One-dimensional gratings were formed by ion implantation and a special regime of laser annealing. The two-dimensional gratings were formed by ion implantation through a metallic net shadow-mark or using photolithography. Also, the first results of in situ investigation of the effect of anisotropic local melting of monocrystalline silicon are presented. In situ time dependences of density (quantity per cm2) of local molten regions are interpreted in the frame of the following model: the existence of a short-lived metastable state, characterized by superheating in the solid phase. The experiments and theoretical calculations crucial to clarify the mechanism of the effect in question are discussed.

Diffraction Dilatometry of Polymethacrylate at Low Temperatures

The linear thermal-expansion coefficient of polymethacrylate is measured in the temperature range from–194 to 0°С. A dilatometric study was performed using optical diffraction.