In this work, we use SrTiO3 and BaTiO3 films (thickness <10nm) epitaxially grown on Si(100) substrates, and x-ray and ultraviolet (UV) photoemission spectroscopy to investigate the effect of surface preparation on chemical and electronic film and interface properties. Depending on the surface treatment, e.g., ex situ UV generated ozone or annealing in oxygen or vacuum, the valence band maximum position shifts by more than 2eV, whereas the oxide core levels shift by less than 0.6eV. These findings indicate that extremely careful cleaning procedures must be applied, as surface composition and film morphology are of paramount importance in the determination of the electronic structure of the crystalline oxides. In addition, the interfaces between SrTiO3 and BaTiO3 and Si are shown to be unstable at annealing temperatures required to thoroughly clean and order the surface.
We report on a Yb(3+)-doped sesquioxide waveguide laser based on a lattice-matched Yb(3+)(3%):(Gd,Lu)(2)O(3) film that has been epitaxially grown on Y(2)O(3) using pulsed laser deposition. Rib-channel waveguides have been structured by reactive ion etching. Laser emission at 976.8 nm was observed under pumping with a Ti(3+):Al(2)O(3) laser at 905 nm. A laser threshold of 17 mW and a slope efficiency of 6.7% have been achieved with respect to input power. For an incident pump power of 200 mW, a maximum output power of 12 mW could be realized.
CuInSe2 surfaces can be cleaned by bombardment with Ar ions at glancing incidence and with energies up to 1.5 keV without change in composition. At near-normal incidence a slight depletion of Cu is observed. The surface crystallinity can be partially restored by annealing to ∼550 °C, without preferential evaporation of an element. On Ar+-cleaned and annealed surfaces, single-crystal low-energy electron diffraction patterns of CuInSe2 have been produced for the first time.
Abstract:We report the first waveguide laser based on a rare-earth-doped sesquioxide. A 2 µm thick lattice matched Nd(0.5%):(Gd, Lu) 2 O 3 film with a nearly atomically flat surface has been epitaxially grown on a Y 2 O 3 substrate, using pulsed laser deposition. The film has been structured with reactive ion etching and a rib channel waveguide laser has been realized. Laser radiation at 1075 nm and 1079 nm has been observed under 820-nm pumping. The laser possesses a threshold power of about 0.8 mW and a preliminary slope efficiency of 0.5% versus incident pump power. A maximum output power of 1.8 mW has been obtained for 370 mW incident pump power.
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