Physical properties of homogeneous TiO₂films prepared by high power impulse magnetron sputtering as a function of crystallographic phase and nanostructure

Abstract

Optical, photo-electrochemical, crystallographic and morphological properties of TiO2 thin films prepared by high power impulse magnetron sputtering at low substrate temperatures (<65 °C) without post-deposition thermal annealing are studied. The film composition—anatase, rutile or amorphous TiO2—is adjusted by the pressure (p ∼ 0.75–15 Pa) in the deposition chamber. The different crystallographic phases were determined with grazing incidence x-ray diffractometry. The surface morphology and size of TiO2 grains/clusters were imaged with atomic force microscopy. Basic plasma parameters were determined by means of the time-resolved Langmuir probe technique. The power density influx on the substrate was estimated from calorimetric probe measurement. The data from calorimetric probe measurements and time-resolved Langmuir probe served as input parameters for the calculation of influx contributions of particular species. The band-gap energy Eg depends on the film composition and crystallographic phase. Optical parameters (refractive index n + ik, transmittance T, reflectance R and absorbance A) are measured as functions of photon energy in the UV–Vis range by spectroscopic ellipsometry. For the rutile and anatase films agreement with the respective bulk phase is found. Incident photon-current conversion efficiency determined by photo-electrochemical measurements reached the highest values (0.312) for the anatase film.

Development of microfabricated TiO2 channel waveguides

“…Similar features were reported for TiO 2 films deposited by sputtering. [15][16][17][18][19][20][21] The refractive index at 500 nm in Fig. 2(b) is 2.49, which is in good agreement with a TiO 2 film prepared under a low pressure condition.…”

Effect of nitrogen doping on TiOxNy thin film formation at reactive high-power pulsed magnetron sputtering

“…3. The discharge current was calculated, using Ohm s law formula, from the voltage drop measured by oscilloscope on the ballast resistor (the method is described in detail in our earlier papers [43,45]). Time evolution of I D shown in Fig.…”

TiO2 Nanotubes on Transparent Substrates: Control of Film Microstructure and Photoelectrochemical Water Splitting Performance

“…Nanocrystalline TiO 2 has highly promising optical, photocatalytic and photoelectrochemical (PEC) performance [4], which have been extensively used for a broad range of applications including environmental purification, organic oxidations [5], solar cells, PEC water splitting, and hydrogen peroxide production [1,2,4,[6][7][8][9][10][11][12].…”

“…With the decrease of the material's dimensions to nanoscale, surface-to-volume ratio and specific surface area increase as well as electronic properties that may also deviate from ideal behavior [13]. Crystal phase and orientation in nanocrystals and thin films have shown a dramatic role in enhancing charge separation, band gap, and surface catalytic properties of TiO 2 nanomaterials [6,[11][12][13].…”