Intrinsic Nitrogen‐doped CVD‐grown TiO₂ Thin Films from All‐N‐coordinated Ti Precursors for Photoelectrochemical Applications

Abstract

N-doped titanium dioxide (TiO 2 ) thin films are grown on Si(100) and indium tin oxide (ITO)-coated borosilicate glass substrates by metal-organic (MO)CVD. The intrinsic doping of TiO 2 thin films is achieved using all-nitrogen-coordinated Ti precursors in the presence of oxygen. The titanium amide-guanidinate complex, [Ti(NMe 2 ) 3 (guan)] (guan ¼ N,N 0 -diisopropyl-2-dimethylamidoguanidinato) has been developed to compensate for the thermal instability of the parent alkylamide [Ti(NMe 2 ) 4 ]. Both of these amide-based compounds are tested and compared as precursors for intrinsically N-doped TiO 2 at various deposition temperatures in the absence of additional N sources. The structure and morphology of TiO 2 thin films are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Rutherford back scattering (RBS), nuclear reaction analysis (NRA), and secondary ion mass spectrometry (SIMS) analyses are performed to determine N content and distribution in the films. The optical and photoelectrochemical properties of TiO 2 thin films on ITO substrates are also examined. N-doped TiO 2 thin films, grown from [Ti(NMe 2 ) 3 (guan)] at 600 8C, exhibit the lowest optical absorption edge (3.0 eV) and the highest visible light photocurrent response. When compared to undoped TiO 2 , while in UV light photoconversion efficiency decreases significantly, the intrinsically N-doped TiO 2 shows enhanced photocurrents under visible light irradiation.

MOCVD of TiO2 thin films from a modified titanium alkoxide precursor

“…Figure (a) shows XRD patterns of TiO 2 thin films grown on Si(100) from [Ti(OPr i ) 2 (deacam) 2 ] as a SSP. As can be observed, the films were amorphous at 500 °C and the onset of TiO 2 (anatase) formation was observed at 600 °C, with an increase of the corresponding reflections at 700 °C, in line with previous observations . Thus, a mixture of TiO 2 (anatase) and rutile phases was observed upon increasing the temperature to 800 °C, in line with previous results .…”

“…Herein, we present the synthesis and characterization of this compound and its evaluation as precursor for MOCVD of TiO 2 thin films, both in the absence [single‐source precursor (SSP)] and in the presence of O 2 in the reaction environment. The films obtained in both cases were subjected to a thorough chemico‐physical characterization, devoting particular attention to the possible incorporation of nitrogen from the ligands into the obtained TiO 2 deposits . Finally, efforts were dedicated to the study of film electrical characteristics ( I – V and C – V ) for their potential applications in MOS devices.…”

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.…”

Electrical and optical properties of TiO2 thin films prepared by plasma‐enhanced atomic layer deposition

“…The well‐known [Ti(NMe 2 ) 4 ] precursor is very sensitive to air and moisture and has limited thermal stability. We have therefore developed a heteroleptic mixed amide Ti compound, namely, tris(dimethylamido)(N,N′‐diisopropyl‐2‐dimethylamidoguanidinato)titanium(IV), [Ti(NMe 2 ) 3 (guan)] (guan = N,N′‐diisopropyl‐2‐dimethylamidoguanidinato), which shows increased thermal stability compared to the parent amide, and successfully used for both ALD and MOCVD process to grow TiO 2 films .…”