Properties And Preparation Of Titanium Silicide Thin Films And Nanowires By APCVD

The Flat Panel Displays (FPDs) are rapidly developing in 21st century. Novel materials with the lower resistivity are required for contact electrodes of the FPDs to enhance the respond performance. Besides, Fabrication of the field-emitters of Field Emission Displays (FEDs) is too complex to step forward. The combination of conductive thin films and nanowires deposited on large area glass by simple methods with low cost will solve the above problems.In this thesis, the films and nanowires of titanium silicides were prepared on the glass substrate by atmosphere pressure chemical vapor deposition (APCVD), using SiFLt and TiCl₄ as precursors. XRD, FESEM, EDX, UV-VIS spectrometer and Four-point probe were employed to characterize structure and properties of the films, respectively. The phase formation in the films and CVD reaction were studied. The formation and growth of TiSi nanowires were also clarified.The results reveal that the deposition of the films is determined by CVD reaction between SiH₄ and TiCl₄.Via controlling the CVD reaction to promote the TiSi₂ formation and depress the Ti₅Si₃ formation at the same time, the TiSi₂ films can be gained with the low resistivity. The mechanism of the films deposition is described as below: SiFLt and TiCl₄ directly reacted in the vapor phase at first, and then the TiSi₂ grains deposited on the glass substrate. The stack density of the TiSi₂ crystalline phase gradually increased and the particles grew up. The films came to continuous and uniform, resulting in the low resistivity. The infrared reflection relys much on the phase formation in the films. Improving the concentration of the TiSi₂ crystalline phase, decreasing the sheet resistance will enhance of the infrared reflection of the TiSi₂ films.The TiSi crystalline nanowires with the orthorhombic structure were prepared on the TiSi2 films deposited on glass substrate. The length of the nanowires is more than several micrometers with the width between 20nm and 40nm. The growth direction is [011]. The growth process involves the self-induced growth of TiSi nanowires via the 'vapor-solid' (VS) growth mode. In the initial stage, the TiSi crystalline nanoislands are formed on TiSi2 particles. After that, an intrinsically anisotropic crystallographic structure of the TiSi crystalline results in the growth along [011] direction of nanowires. The silicide nanoneedles, core-sheath nanowires are also prepared by APCVD.Moreover, nanowires and films of titanium silicides are also prepared on Si (111) substrate. The nanowires growth on films is not affected by underlying substrate.