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The production of free-standing large aspect ratio metal nanofilms by femtosecond laser separation
(2009)
We demonstrate a new method for the production of free-standing metal films of thickness down to several tens of nanometres. Films of different metals as well as multilayer structures have been produced by means of femtosecond laser-induced separation of evaporated layers from a plane glass surface. This technology enables the production of large-area films with different properties for optical or nanotechnological applications. We study the properties of the film and demonstrate the possibility of high-pass filtering of electrons with an energy of several keV by means of the free-standing films. The physical mechanisms leading to the film separation under femtosecond laser radiation are discussed.
Redistribution of deep selenium and sulfur impurities in silicon upon surface doping with phosphorus
(2009)
The study is concerned with the effect of short-term high-temperature heating on Si:Se and Si:S samples, whose surface layers are doped with phosphorus to high concentrations. It is found that the resistivity of the wafers substantially increases deep in the bulk within up to similar to 10 mu m. The experimental data suggest that this effect is due to enhanced diffusion of chalcogen in the presence of the phosphorus-doped surface region. The mechanism of the effect is the injection of nonequilibrium interstitial silicon atoms from the layer heavily doped with phosphorus to the bulk of the sample. This results in a shift of the equilibrium between the concentrations of substitutional and interstitial impurity atoms towards higher concentrations of interstitials and, as a consequence, towards the increase in the relative content of the fast-diffusing interstitial component of the impurity.
We present a novel unimorph deformable mirror with a diameter of only 10 mm that will be used in adaptive resonators of high power solid state lasers. The relationship between applied voltage and deformation of a unimorph mirror depends on the piezoelectric material properties, layer thicknesses, boundary conditions, and the electrode pattern. An analytical equation for the deflection of the piezoelectric unimorph structure is derived, based on the electro-elastic and thin plate theory. The validity of the proposed analytical model has been proven by numerical finite-element modelling and experimental results. Our mirror design has been optimized to obtain the highest possible stroke and a high resonance frequency.