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S. A. Mulenko
«Pulsed Laser Deposition of Thin Iron and Chromium Silicide Films with Large Thermoelectromotive Force Coefficient»
PACS numbers: 72.20.Pa, 73.22.-f, 73.50.Lw, 73.61.-r, 81.15.Fg, 81.16.Mk, 85.80.Fi
Nanostructures in the form of thin films exhibiting the semiconductor properties with a narrow energy-band gap are deposited from the CrSi2 and ?-FeSi2 targets by means of the pulsed laser deposition (PLD) assisted with an excimer KrF laser. The films deposited from CrSi2 target on the ?100?Si substrate at 293 K and 740 K manifest the band gaps Eg ? 0.09 eV and 0.18 eV, respectively. The films deposited from ?-FeSi2 target on the ?100?Si substrate at the same conditions manifest the band gaps Eg ? 0.16 eV and 0.31 eV, respectively. The upper-range value of thermoelectromotive force coefficient (Seebeck coefficient), S, for the CrSi2-based films deposited on heated substrate at 740 K is about 1.4 mV/K at 300 K???T???340 K. The largest S coefficient for the ?-FeSi2-based films deposited on heated substrate too is about 1.5 mV/K within the same temperature range. With the higher Eg, the higher S coefficient is obtained. The XRD analysis reveals that films deposited on the Si substrates have a polycrystalline structure, and films deposited on the SiO2 substrates are amorphous. As regards the S coefficient for films deposited on the Si and SiO2 substrates, this coefficient is higher for polycrystalline films than for amorphous deposits. The larger the semiconductor-phase concentration in the deposited films, the higher the S coefficient. So, the PLD based on an excimer KrF laser is an effective method for the deposition of nanostructures in the form of thin films, which are quite suitable for thermal sensors operating at moderate temperatures.