Alexander F. Banishev

Generation and accumulation of dislocations on the silicon surface under the action of pulse-periodic emission from a YAG: Nd laser

Solid-phase damage of the silicon surface due to the generation and accumulation of dislocations is studied. The dislocations are generated under the pulse-periodic action of a YAG: Nd laser. The number of laser pulses that causes surface damage vs. power density and pulse repetition period is derived. A mechanism responsible for the generation and accumulation of the dislocations at the surface is suggested.

Peculiarities of solid-phase silicon surface laser-induced damage in vacuum and in various gases

In the paper the peculiarities of relief inhomogeneities formation on silicon surface were investigated at irradiation by submicrosecond laser pulses in various gases. It was shown that the development and relaxation time of these inhomogeneities poorly depends on a type of gas.

Investigation of regimes of structural defect accumulation and relaxation on silicon surface under periodic-pulse laser radiation

The paper pursues an experimental investigation on solid- phase destruction of thin surface silicon layer (h approximately equals 10-4 cm) in vacuum, related to accumulation of dislocations under periodic action of short pulses. It has been concluded that the destruction of sample surface will be governed by competition of processes of dislocation growth and relaxation. It has been shown that the destruction of surface is caused by the requisite number Nc of laser pulses. The plots of Nc against power density and pulse repetition period have been constructed.

Laser-initiated anomalous diffusion of oxygen in a surface silicon layer enriched with defects

The effect of anomalously slow relaxation of deformation of silicon surface after laser stimulation is revealed and described. This effect is attributed to “cold” diffusion of oxygen in the surface layer enriched with defects.

Abnormal increase of time of oxygen diffusion with oxidation of silicon surface under action of powerful laser pulses

The paper presents an investigation of deformation response of monocrystalline silicon surface to the action of short laser pulses in the air and in vacuum P approximately equals 10-2 Torr. An anomalously continuous change of the surface relief was identified on irradiation in the air. The observable phenomenon is explained by oxidation of surface layer, enriched with defects.

Emission of particles by solid-phase laser-induced destruction of silicon surface

This paper presents the results of investigation into the process of silicon surface solid-phase destruction under YAG:Nd laser pulses. The glow was registrated that was due to emission of the heated particles from the sample surface, which can be caused by microexplosions and microcracking of the surface owing to great thermoelastic stresses in the interaction area.

Variation of the deformation response of a silicon surface due to surface layer saturation with defects under pulsed and pulse-periodic laser radiation

The method of probe beam scattering was used to study the peculiarities of monocrystalline Si surface destruction under pulsed laser irradiation. The shape of scattering signal showed that in the exposure region a surface layer rich in defects is formed. A study has been made on its influence on dynamics of sample surface deformation.

Influence of external pressure and gas type on mechanism and velocity of metal punching with Nd:YAG-laser pulses

The high-power laser beam interaction with the surface of metals (W, Fe, Ti, stainless steel) has been studied under high external pressures of the inert (Ar) and active (O2) gases. The velocities of punching the samples have been measured at laser pulse power densities I equals 0.5 multiplied by 106 - 107 W/cm2 in the beam revealed in punching velocities depending on the type of external gas. The dynamics of variations in the shape of high-power laser pulse reflected from the surface (W, Fe, Ti) has been studied.

Nonstationary plasma-thermo-fluid dynamics and transition in processes of deep penetration laser beam-matter interaction

A qualitative analysis of the role of some hydrodynamic flows and instabilities by the process of laser beam-metal sample deep penetration interaction is presented. The forces of vapor pressure, melt surface tension and thermocapillary forces can determined a number of oscillatory and nonstationary phenomena in keyhole and weld pool. Dynamics of keyhole formation in metal plates has been studied under laser beam pulse effect ((lambda) equals 1.06 micrometers ). Velocities of the keyhole bottom motion have been determined at 0.5 X 105 - 106 W/cm2 laser power densities. Oscillatory regime of plate break- down has been found out. Small-dimensional structures with d-(lambda) period was found on the frozen cavity walls, which, in our opinion, can contribute significantly to laser beam absorption. A new form of periodic structure on the frozen pattern being a helix-shaped modulation of the keyhole walls and bottom relief has been revealed. Temperature oscillations related to capillary oscillations in the melt layer were discovered in the cavity. Interaction of the CW CO2 laser beam and the matter by beam penetration into a moving metal sample has been studied. The pulsed and thermodynamic parameters of the surface plasma were investigated by optical and spectroscopic methods. The frequencies of plasma jets pulsations (in 10 - 105 Hz range) are related to possible melt surface instabilities of the keyhole.

Oscillatory regime of metallic plate breakdown under laser beam

Dynamics of keyhole formation in metal plates of Mo, W, Ni, stainless steel have been studied under the solid-state laser pulse effect ((lambda) equals 1.06 micrometers ). Velocities of the keyhole bottom motion have been determined for these metals in the (0.5 (DOT) 105 - 106) W/cm2 range of irradiated power densities. A pulse regime of plate breakdown has been found out. Small-dimensional structures with d is congruent to 1 micrometers period were found on the keyhole walls, which, in our opinion, can contribute significantly to laser beam absorption. A new form of periodic structure has been revealed, being a helix-shaped modulation of the keyhole walls and bottom relief. Temperature variation were discovered in the keyhole, related to capillary waves propagation in the melt layer.