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

Authors


  • The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement number ENHANCE-238409. R.B. is thankful for financial support by the MIWFT-NRW.

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.

Ancillary