Investigating semiconductor layered systems of photonics

The structure of a heterostructures-based semiconductor laser is experimentally investigated by complex means involving systems of scanning electron microscopy, scanning probe microscopy, and Raman spectroscopy. The possibilities of high-resolution microscopy for diagnostics of layered microelectronic systems are demonstrated.     

Femtosecond laser nanostructuring of a tungsten surface

Tungsten surface nanostructuring is performed using the radiation of a Yb:KGW femtosecond laser in air and in liquid nitrogen. Arrays of linear nanostructures and nanorods of tungsten and tungsten nitride are fabricated on the surfaces of targets. Possible scenarios of transforming surface nanostructures of one type into another and the formation of network-like relief are considered.     

Pulse laser deposition of cluster nanostructures from colloidal single-component systems

We study the formation and deposition of clusters of nanoparticles from colloidal systems onto a support surface as a result of local pulse laser impact. The processes of abnormal diffusion influencing the formation of relief due to changes in the diffusion coefficient near surface irregularities are analyzed. Numerical simulation is performed for the mechanism of deposition of particles from the colloidal system as a result of local laser impact.     

Melting of carbon heated by focused laser radiation in air at atmospheric pressure and temperature below 4000 K

The melting of carbon at a pressure of about 1 atm is observed. The escape of liquid carbon from the heating region and its spread over the sample surface are observed in the experiments. The structural changes in graphite occurring in the melting region are determined from scanning tunneling microscope (STM) images obtained by means of an atomic force microscope and from Raman spectra. The STM images exhibit significant rearrangement of the structure of the graphite surface in the region of the escape of liquid carbon. The Raman spectra show that the graphite ordering degree increases significantly.     

Processing materials in the mode of multiple filamentation of femtosecond laser radiation

Results are presented from experimental studies of the filamentation of femtosecond laser radiation in a transparent medium. Schemes for registering plasma channels of filaments, conical emission, and the spatial distribution of radiation intensity are provided. The results from laser action on a target of stainless steel in the multiple filamentation mode.     

Model of the subsurface overheating of carbon samples upon laser impact in liquid nitrogen

A qualitative model describing the subsurface overheating of carbon samples exposed to femtosecond laser irradiation in liquid nitrogen is proposed for purposes of simulation. To a large degree, the model has universal applicability. A distinctive feature of this model is the principle of interactive control, which allows investigated characteristics to be adapted to observed experimental data.     

Carbine formation as a result of graphite sample surface heating by laser radiation at atmospheric pressure to a temperature not exceeding 4000 K

Raman spectra from various areas of a laser crater resulted from carbon melting at a temperature not exceeding 4000 K and a pressure of the order of atmospheric were studied. The spectra were excited by the second harmonic of the Nd:YAG laser at a wavelength of 503 nm. Graphite and carbine peaks were observed in the Raman spectra, which suggests that small amounts of carbine in addition to graphite are formed during liquid carbon crystallization.     

Selective membranes with biologically active surface

Composite membranes have been developed for media where accumulation of pathogenic microorganisms on the membrane surface is possible. It has been proposed to use as membrane skin layer a polymer nanocomposite modified with detonation nanodiamonds containing surface-bound dibutyltin dilaurate as biologically active substance, which should ensure self-cleaning of the membrane surface.