Melting and solidification of the surface layer of single-crystal silicon heated by pulsed laser radiation

Abstract

Please note that terms and conditions apply. Melting and solidification of the surface layer of single-crystal silicon heated by pulsed laser radiation View the table of contents for this issue, or go to the journal homepage for more 1995 Quantum Electron. 25 774 Abstract. The methods of optical probing and of detection of pulsed thermal radiation were used in a study of crystal <-> melt phase transitions in silicon heated by nanosecond ruby laser radiation. An electron-diffraction investigation was made of the structural state of the semiconductor surface. Inhomogeneity of the phase transitions was demonstrated experimentally. Local variations of the melting and crystallisation rates result in roughness of the phase boundary. Probing of this boundary through the base revealed deviations from the specular reflection of the probe beam. A numerical solution of the Stefan problem provided a description of the dynamics of changes in the reflected radiation flux, governed mainly by the transient optical absorption in the heated layer of a single crystal. A possible reduction in the supercooling of the molten surface during epitaxial crystallisation was insignificant. The presence on the irradiated surface of foreign micron-size particles could result in local lateral crystallisation of the melt and formation of unoriented silicon inclusions in the thin surface layer of the single crystal.

Reliable and well-controlled synthesis of noble metal nanoparticles by continuous wave laser ablation in different liquids for deposition of thin films with variable optical properties

“…We note that nanoparticle aggregation is prevented in this regime because of the liquid convection flow that continuously removes particles from the laseraffected zone during laser irradiation. The convection flow takes place due to the strong temperature gradients and depends both on liquid properties and on laser parameters (Gatskevich et al 1995). Aggregation becomes, however, possible after the end of laser irradiation.…”

Phase transitions in erbium-doped silicon exposed to laser radiation

“…We used a ruby laser with a pulse length τ = 80 nsec and λ em = 0.69 μm. The optical path of the laser produced a highly homogeneous laser spot [3,4]. The unevenness of the energy distribution of a single pulse in the spot was less than ±5%.…”

“…Doping of Er + ions with subsequent high-temperature thermal annealing is the most common method of introducing rare-earth dopants into silicon. Silicon is additionally doped with oxygen ions in order to increase the solubility of Er in Si and to increase the luminescence intensity of the 4 I 13/2 → 4 I 15.2 transition [1]. The use of nanosecond laser action on doping of Si layers with Er has been little studied as an alternative to traditional thermal annealing [2].…”