http://dspace.nbuv.gov.ua:80/handle/123456789/114614 2026-04-09T10:47:50Z http://dspace.nbuv.gov.ua:80/handle/123456789/121334 Growth kinetics of PbS nanocrystals in organo-metallic Langmuir-Blodgett films studied by optical absorption spectroscopy Savin, Yu.N. Formation and growth of lead sulfide nanocrystals in lead stearate Langmuir-Blodgett (LB) films are investigated using the optical absorption spectroscopy method. The kinetics of changes in the concentration of lead ions in different states formed during the growth process, as well as the evolution of the nanocrystal average size versus growth time, are studied. Irrespective of the primary Pb2+ ion concentration in films, found was a nonlinear dependence of the nanoparticle growth rate vs time: at the initial stage the growth rate is higher than at the final one. The idea of diffusive decomposition of solid solution is used to analyze the experimental results. It is shown that high concentrations of metal ions at the interfaces of LB-film monolayers as well as diffusion restrictions of mass-transfer process play a decisive role in the formation and growth of nanocrystals in ordered organic matrixes. 2002-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/121333 Balance model for contactless chemo-mechanical polishing of wafers Grigoriev, N.N.; Kravetsky, M.Yu.; Paschenko, G.A.; Sypko, S.A.; Fomin, A.V. We developed a physical model for polishing. It makes it possible to determine physico-chemical processes occurring at contactless chemo-mechanical polishing (CMP) of crystal surfaces. A balance equation for diffusion, convection and chemical flows is used to describe processes that are proceeding in the stationary case. The analytical expressions are obtained that relate polishing rate and surface form for processed material to the physical parameters of the proceeding processes. It was found that macrorelief of the processed surface depends not only on the velocity of polishing plate motion but also on the gap between the processed wafer and polishing plate, as well as active component diffusion in the etching solution. One would expect that, at processing conditions discussed, the surface form is the same for different materials, whatever the active component concentration and chemical reaction constant. The polishing rate substantially depends on the concentration of the etchant active component, chemical reaction, physical properties of sample material and etching liquid. It is shown that the inverse rate of dissolution is the sum of inverse limiting rates of chemical, diffusion and convection stages of the process. The expressions are obtained that make it possible to optimize technological modes of polishing. 2002-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/121332 Investigation of the effect of technological parameters on efficiency of chemical string cutting of semiconductor materials Kravetsky, M.Yu.; Sypko, S.A.; Fomin, A.V. On the basis of the balance model for convection-diffusion processes that occur during string chemical cutting (CC) of samples, we derive an analytical expression for the limiting CC rate at maximal use of etching agent. Comparison between the experimental and theoretical dependencies of CC rates for InSb, HgCdTe and CdTe samples on the velocity of string motion and diameter of sample being cut demonstrates good agreement of the experimental results with the model notions. It is shown that diffusion kinetics of the CC process is retained even at very high velocities of string motion. The experimentally obtained value of CC rate is approaching 3 mm/min. The dependencies studied point at resources for increase of CC efficiency. Some technical modification of the equipment, related primarily to increasing velocity of motion of the etching liquid carrier, will make the CC technique able to meet competition with the abrasion techniques in technological lines for manufacturing of semiconductor devices. 2002-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/121331 Effect of mechanical stress on operation of diode temperature sensors Borblik, V.L.; Shwarts, Yu.M.; Venger, E.F. Effect of uniaxial elastic strain (of moderate magnitude) on operation of n+- p-type diode temperature sensor made in silicon is considered theoretically. It is assumed that operating current and stress direction coincide with each other and with one of three main crystallographic directions [100], [110] and [111]. The cases of long and short diodes, compressive and tensile stresses are studied. It is shown that, under such conditions, two components of the piezojunction effect (namely: change in the minority carrier mobility and change in the intrinsic carrier concentration) act oppositely to each other. As a result, effect of longitudinal parasitic mechanical stress on indications of the silicon diode temperature sensors proves to be minimal in the direction of [100]-type [111]-type as it would be expected from rather than piezoresistivity of n-Si. 2002-01-01T00:00:00Z