Organic-inorganic hybrid or alloy films have great potential as a functional material because they have structural flexibility owing to the presence of an organic moiety. Here organic-inorganic hybrid films were grown by molecular layer deposition (MLD) by using trimethylaluminum and p-phenylenediamine. Although the hybrid films could be grown via the self-limiting growth mechanism of MLD, the hybrid films were severely air sensitive. The stability problem of the hybrid films could be solved by alloying the hybrid layer with Al 2 O 3 layers. The alloy films, which were grown by repeating supercycles with one subcycle for the hybrid layer and four subcycles for the Al 2 O 3 layers, showed excellent dielectric properties: a leakage current density of $2.3 Â 10 À8 A cm À2 at 1 MV cm À1 ; a dielectric breakdown field at $2.9 MV cm À1 ; and a dielectric constant of $6.2. Interestingly, charge trapping behavior was clearly observed in the alloy film. The charge trapping ability of the alloy film was verified with a charge trapping memory capacitor in which the alloy film was inserted as a charge trapping layer.
Atomic layer deposition (ALD) of TiO 2 thin film from TiCl 4 and H 2 O has been intensively studied since the invention of ALD method to grow thin films via chemical adsorptions of two precursors. However the role of HCl which is a gaseous byproduct in ALD chemistry for TiO 2 growth is still intriguing in terms of the growth mechanism. In order to investigate the role of HCl in TiO 2 ALD, HCl pulse and its purging steps are inserted in a typical sequence of TiCl 4 pulse-purge-H 2 O pulse-purge. When they are inserted after the first-half reaction (chemisorption of TiCl 4 ), the grown thickness of TiO 2 becomes thinner or thicker at lower or higher growth temperatures than 300 o C, respectively. However the insertion after the second-half reaction (chemisorption of H 2 O) results in severely reduced thicknesses in all growth temperatures. By using the result, we explain the growth mechanism and the role of HCl in TiO 2 ALD.
When atomic layer deposition (ALD) is performed on a porous material by using an organometallic precursor, minimum exposure time of the precursor for complete coverage becomes much longer since the ALD is limited by Knudsen diffusion in the pores. In the previous report by Min et al. (Ref. 23), shrinking core model (SCM) was proposed to predict the minimum exposure time of diethylzinc for ZnO ALD on a porous cylindrical alumina monolith. According to the SCM, the minimum exposure time of the precursor is influenced by volumetric density of adsorption sites, effective diffusion coefficient, precursor concentration in gas phase and size of the porous monolith. Here we modify the SCM in order to consider undesirable adsorption of byproduct molecules. TiO 2 ALD was performed on the cylindrical alumina monolith by using titanium tetrachloride (TiCl 4 ) and water. We observed that the byproduct (i.e., HCl) of TiO 2 ALD can chemically adsorb on adsorption sites, unlike the behavior of the byproduct (i.e., ethane) of ZnO ALD. Consequently, the minimum exposure time of TiCl 4 (~16 min) was significantly much shorter than that (~ 71 min) of DEZ. The predicted minimum exposure time by the modified SCM well agrees with the observed time. In addition, the modified SCM gives an effective diffusion coefficient of TiCl 4 of ~1.78 × 10 −2 cm 2 /s in the porous alumina monolith.
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