| Titanium dioxide (TiO2) and strontium titanate (SrTiO 3) are promising candidates as high dielectric constant (ϵ) materials in emerging dynamic random access memory capacitors and electroluminescent displays, and as gate insulator in complementary metal-oxide-semiconductor devices. This thesis focuses on the development of chemical vapor deposition routes to TiO2 and SrTiO3 thin films using 2,2,6,6-tetramethyl-3,5-heptanedionate-type complexes, namely Ti(tmhd)3 and Sr(tmhd)2 as the elemental sources. For TiO2, systematic studies led to the identification of a wide process window for pure films. As-deposited films exhibited a weakly crystallized anatase structure, or a mixture of anatase-rutile structures. An anatase to rutile transformation was induced upon annealing. ϵ values of 85 and 110 were obtained for, respectively (112)-oriented anatase films and films having a mixed anatase-rutile structure with (110) preferred orientation. ϵ was directly proportional to film thickness, a behavior attributed to the presence of an interfacial silicon oxide (SiO2) layer that lowered ϵ for thinner films.; The I–V characteristics of the Al/TiOx/Si capacitors indicated rectification with the Al/TiOx contact blocking electron and hole injection, while the Si/TiOx contact acting as electron injector. A field strength of 1.2 MV/cm at 10−4 A was measured for a 200nm thick TiOx film. Leakage current densities (JL) of the films below 5000Å decreased upon annealing, a trend attributed to improved interfacial properties, because of interfacial SiO2 formation. JL of films thicker than 5000Å increased upon annealing due to the formation of micro-cracks.; For SrTiO3, varying compositions (0.44 < Sr/Ti < 3) were obtained by controlling elemental source temperatures. As-deposited films were predominantly crystalline cubic perovskite, mixed with amorphous oxide phases. Annealing the Sr-rich films resulted in the crystallization of the amorphous SrO phases, with the insertion of SrO planes into the base SrTiO 3 lattice. Alternatively, annealing of films with composition of Sr/Ti = 2 at 700°C resulted in a Sr2TiO4crystal structure.; An ϵ of 57 was obtained for as-deposited, near-stoichiometric films. This low value, as compared to bulk, was due to the presence of interfacial SiO2 and oxide phases (TiO2 and SrO), as well as poor film crystallinity. A lowest JL of 1.67 × 10−9 A/cm2 was obtained at 2 volts for a Sr/Ti ratio of 1.16. JL of as-deposited films increased upon annealing, a trend attributed to the crystallization of the amorphous phases. |
