Laser-assisted synthesis of semiconductor chromium disilicide films

Different photo-assisted techniques were employed for chromium disilicide (CrSi2) semiconductor film fabrication. Flash evaporation of CrSi2 powder on the Si substrate heated to ∼740 K leads to the formation (according to XRD study) of amorphous films. Post-annealing at 920 K leads to the formation of polycrystalline CrSi2 phase. Crystallization is improved by further annealing with 1500 Q-Switched Nd:YAG laser pulses. Optical properties of the as deposited and annealed CrSi2 films have been investigated in the 240-1100 nm spectral range by using spectroscopic ellipsometry. The formation of CrSi2 semiconductor phase was additionally confirmed by the temperature dependence of electrical resistance of the films treated by Q-switched Nd:YAG laser. The band gap for intrinsic conductivity results Eg ≅ 0.2 eV. Backward laser-induced film transfer (LIFT) was also used for CrSi2 film deposition from bulk material on Si substrates. Pulsed CO2 laser was employed for this purpose, because of transparency of silicon at the 10.6 μm wavelength. Measurements of the electrical resistance of the deposited films as a function of temperature showed their semiconductor behavior (Eg = 6 × 10−4 eV). Chromium disilicide films were also deposited by congruent pulsed laser ablation deposition on Si substrates either at room temperature or heated to about 740 K. In this last case the deposit exhibits semiconducting properties with Eg ≅ 0.18 eV.