Off-axis Pulsed Laser Deposition Research Articles

Stoichiometry and thickness variation of YBa2Cu3O7−x in off-axis pulsed laser deposition

We studied the dependence of the thickness and stoichiometry of YBa2Cu3O7−x deposited in an off-axis pulsed laser deposition geometry on the background oxygen pressure and the distance from the target. We observe a biregional drop-off in thickness with increasing axial distance, with the border between the two regions at 3–4 cm away from the target. The thickness was proportional to the deposition pressure raised to the 2/3 power, at axial distances greater than 4 cm. Atomic force microscope studies of the two regions showed the density of micron sized particles to be 2–5×104/cm2 within the first region (closer to the target) with no such particles in the second region. The stoichiometric composition did not exhibit this biregional dependence. At an optimum oxygen pressure of 200 mTorr, we were able to obtain a stoichiometrically uniform region as large as 3×4 cm2.

C-Axis Oriented Lithium Niobate Films on (001) Magnesium Oxide by Pulsed Laser Deposition

AbstractFor the first time, epitaxial c-axis oriented lithium niobate (LiNbO3) films were grown on MgO (001) substrates. This orientation is relevant to the monolithic integration of LiNbO3 with GaAs for waveguiding, frequency doubling, and other opto-electronic applications. The epitaxial orientation relationship is (001 ) LiNbO3 parallel to (001) MgO and [100] LiNbO3 parallel to [110] MgO. Four equivalent in-plane orientations were observed, such that the lithium or niobium atoms along the [100] axis of LiNbO3 are bonded to the oxygen atoms on diagonal comers of the MgO unit cell. These epitaxial films were prepared by off-axis pulsed laser deposition at substrate temperatures of 775–800 °C in a 15–50 mTorr mixture of 5% O3 in O2.

Transparent conducting thin films of GaInO3

GaInO3 is recently identified transparent conducting material which is structurally and chemically distinct from indium tin oxide [R. J. Cava, J. M. Phillips, J. Kwo, G. A. Thomas, R. B. van Dover, S. A. Carter, J. J. Krajewski, W. F. Peck, Jr., J. H. Marshall, and D. H. Rapkine, Appl. Phys. Lett. 64, 2071 (1994)]. We have used both dc reactive sputtering in the on- and off-axis geometries and pulsed laser deposition to grow films of this material. Layers of pure GaInO3 as well as those partially substituted with Ge for Ga or Sn for In have been studied. Both growth techniques are capable of producing films with conductivity ∼400 (Ω cm)−1 and transmission as high as 90% throughout the visible spectrum for ∼1-μm-thick films. The growth techniques differ in the morphology of the films produced as well as in the degree of dopant incorporation that can be achieved. A post-growth anneal in H2 can help produce an optimized oxygen content and a reduction of resistivity. Hall measurements indicate a carrier concentration up to 4×1020 cm−3 for all films and a Hall mobility up to 10 cm2/(V s). Doping appears to be due both to oxygen vacancies and aliovalent ion substitution.