MOCVD of TiO₂ Thin Films using a Heteroleptic Titanium Complex: Precursor Evaluation and Investigation of Optical, Photoelectrochemical and Electrical Properties

Abstract

A new heteroleptic titanium precursor with a mixed oxygen/nitrogen coordination sphere [Ti(dmap)2(NMe2)2] (Hdmap = 1–dimethylamino–2–propanol) is synthesized by a simple elimination reaction on tetrakis–dimethylaminotitanium(IV) [Ti(NMe2)4]. The compound shows encouraging results in terms of chemical and thermal stability compared to the parent alkyl amide [Ti(NMe2)4], and is therefore more suitable for MOCVD applications. TiO2 thin films are grown on Si(100) and ITO‐coated borosilicate glass substrates via MOCVD in the temperature range 500–800°C. The deposition temperature has a significant effect on the phase and microstructure of the TiO2 films obtained, which influences the functional properties. The optical bandgaps of the films are in the range 2.92–3.36 eV. The best photocurrent response (1.5 mA cm−2 under AM 1.5G conditions) in aqueous electrolytes is observed for films grown at 700°C having improved crystallinity and porous columnar structure.

Formation of mononuclear N,O-chelate zirconium complexes by direct insertion of epoxide into tetrakis(dimethylamido)zirconium: highly promising approach for developing an ALD precursor of ZrO2 thin films

“…MCO with high purity (7.01 g, yield 72.1%) was obtained by drying with CaH 2 at 50 °C and distillation. 1 H and 13 C NMR spectra of the product were consistent with the reported one (Fig. S1 and S2 †).…”

“…Tris(dimethylamino)cyclopentadienyl zirconium (CpZr(NMe 2 ) 3 ) was obtained from DNF company, Korea. Proton nuclear magnetic resonance ( 1 H NMR) and 13 C NMR spectra were recorded in deuterated chloroform (CDCl 3 ) or deuterated benzene (C 6 D 6 ) using a Bruker instrument (600 MHz). The crystal, which was coated with Paratone-N oil at −20 °C, was mounted on a Microloop.…”

“…For example, the Devi group reported the synthesis of [(Me 2 N) 2 Ti(dmap) 2 ] and [(Me 2 N) 3 Ti(dmap)] at −78 °C and −40 °C, respectively, by the dropwise addition of Hdmap to [Ti(NMe 2 ) 4 ] solution in hexane (where dmap is OCH(Me)CH 2 NMe 2 ). 13,14 Recently, Park et al synthesized several novel Zr complexes by the slow dropwise addition of one or two equivalents of 4-(dimethylamino)-2,3-dimethylbutan-2-ol (HOCMe 2 CHMeCH 2 NMe 2 ) to TDMAZ solution at room temperature, and applied them as the ALD precursor of the ZrO 2 thin film. 15 Unfortunately, structural characterization of these precursors was not presented in these reports.…”

“…15 Unfortunately, structural characterization of these precursors was not presented in these reports. [13][14][15] Until now, there have been very few reports on the synthesis of mononuclear alkylamide/donor-functionalized alkoxide Zr precursor with detailed structural information. [4][5][6][7] Thus, the development of a new method to construct the mononuclear Zr complex with mixed ligand aminoalkoxide/alkylamide is desirable and significant for its application in ALD.…”

Fabrication of Gold/Titania Photocatalyst for CO2 Reduction Based on Pyrolytic Conversion of the Metal–Organic Framework NH2-MIL-125(Ti) Loaded with Gold Nanoparticles

“…light absorption shifted to the visible range. [72][73][74][75][76] However, we did not study this effects herein and focused on UV illumination/photo-irradiation exclusively. Note, comparison of TiO2 with P-25 ( Figure 7) indicate that such kind of doping is less important than the modification with GNPs.…”