Growth of calcium carbonate by the atomic layer chemical vapour deposition technique

Thin films of CaCO3 (calcite) have been grown with the atomic layer chemical vapour deposition (ALCVD) technique, using Ca(thd)2 (Hthd=2,2,6,6-tetramethylheptan-3,5-dione), CO2, and ozone as precursors. Pulse parameters for the ALCVD-type growth are found and self-limiting reaction conditions are established between 200 and 400 °C. Calcium carbonate films have been deposited on soda-lime glass, Si(100), α-Al2O3(001), α-Al2O3(012), α-SiO2(001), and MgO(100) substrates. The observed textures were: in-plane oriented films with [100](001)CaCO3‖ [100](001)Al2O3 and [100](001)CaCO3‖[110](001)Al2O3 on α-Al2O3(001), amorphous films on α-Al2O3(012) when grown at 250 °C, and columnar oriented films on soda-lime glass, Si(001), α-SiO2(001), and MgO(100) substrates with (00l) and (104) parallel to the substrate plane at 250 and 350 °C, respectively. The film topography was studied by atomic force microscopy and AC impedance characteristics were measured on as-deposited films at room temperature. The films were found to be insulating with a dielectric constant (er) typically approximately 8. Thin films of CaO were obtained by heat treatment of the carbonate films at 670 °C in a CO2-free atmosphere, but the thermal decomposition led to a significant increase in surface roughness.