UV radiation enhanced oxygen vacancy formation caused by the PLD plasma plume

Pulsed Laser Deposition is a commonly used non-equilibrium physical deposition technique for the growth of complex oxide thin films. A wide range of parameters is known to influence the properties of the used samples and thin films, especially the oxygen-vacancy concentration. One parameter has up to this point been neglected due to the challenges of separating its influence from the influence of the impinging species during growth: the UV-radiation of the plasma plume. We here present experiments enabled by a specially designed holder to allow a separation of these two influences. The influence of the UV-irradiation during pulsed laser deposition on the formation of oxygen-vacancies is investigated for the perovskite model material SrTiO3. The carrier concentration of UV-irradiated samples is nearly constant with depth and time. By contrast samples not exposed to the radiation of the plume show a depth dependence and a decrease in concentration over time. We reveal an increase in Ti-vacancy–oxygen-vacancy-complexes for UV irradiated samples, consistent with the different carrier concentrations. We find a UV enhanced oxygen-vacancy incorporation rate as responsible mechanism. We provide a complete picture of another influence parameter to be considered during pulsed laser depositions and unravel the mechanism behind persistent-photo-conductivity in SrTiO3

Single crystal perovskites analyzed using X-ray photoelectron spectroscopy: 3. LaAlO3(001)

X-ray photoelectron spectroscopy (XPS) was used to analyze a commercially available LaAlO3(001) bulk single crystal. XP spectra were obtained using incident monochromatic Al Kα radiation at 0.83401 nm. A survey spectrum together with La 3d, O 1s, C 1s, La 4p, Al 2s, La 4d, Al 2p, La 5s, O 2s and La 5p core level spectra and the valence band are presented. The spectra indicate the principle core level photoelectron and Auger electron signals and show only minor carbon contamination. Making use of the O 1s, La 4d, Al 2p lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed crystal surface of LaAl1.03O2.23

Single crystal perovskites analyzed using X-ray photoelectron spectroscopy: 4. (LaAlO3)0.3(Sr2TaAlO6)0.7(001)

X-ray photoelectron spectroscopy (XPS) was used to analyze a commercially available (LaAlO3)0.3(Sr2TaAlO6)0.7 (001) bulk single crystal. XP spectra were obtained using incident monochromatic Al Kα radiation at 0.83401 nm. A survey spectrum together with La 3d, O 1s, C 1s, Sr 3p, Ta 4d, La 4p, Sr 3d, Al 2s, La 4d, Al 2p, Ta 5p, La 5s, Ta 4f, O 2s, Sr 4p and La 5p core level spectra and the valence band are presented. The spectra indicate the principle core level photoelectron and Auger electron signals and show only minor carbon contamination. Making use of the O 1s, Sr 3d, La 4d, Al 2p Ta 4f lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed crystal surface of La0.34Sr0.88Al0.82Ta0.43O3

Single crystal perovskites analyzed using X-ray photoelectron spectroscopy: 2. YAlO3(110)

X-ray photoelectron spectroscopy (XPS) was used to analyze a commercially available YAlO3(110) bulk single crystal. XP spectra were obtained using incident monochromatic Al Kα radiation at 0.83401 nm. A survey spectrum together with O 1s, Y 2p, C 1s, Y 3d, Al 2p, Y 4p, and O 2s core level spectra and the valence band are presented. The spectra indicate the principle core level photoelectron and Auger electron signals and show only minor carbon contamination. Making use of the O 1s, Y 3d, Al 2p lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed crystal surface of YAl1.06O2.48

Single crystal perovskites analyzed using X-ray photoelectron spectroscopy: 3. LaAlO3(001)

X-ray photoelectron spectroscopy (XPS) was used to analyze a commercially available LaAlO3(001) bulk single crystal. XP spectra were obtained using incident monochromatic Al Kα radiation at 0.83401 nm. A survey spectrum together with La 3d, O 1s, C 1s, La 4p, Al 2s, La 4d, Al 2p, La 5s, O 2s and La 5p core level spectra and the valence band are presented. The spectra indicate the principle core level photoelectron and Auger electron signals and show only minor carbon contamination. Making use of the O 1s, La 4d, Al 2p lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed crystal surface of LaAl1.03O2.23