AVS 53rd International Symposium
    Thin Film Monday Sessions
       Session TF-MoM

Paper TF-MoM1
Spatially Controlled Nano-Scale Doping of Er@sup 3+@ in Y@sub 2@O@sub 3@ by Atomic Layer Deposition

Monday, November 13, 2006, 8:00 am, Room 2022

Session: ALD and Applications I
Presenter: J. Hoang, University of California, Los Angeles
Authors: J. Hoang, University of California, Los Angeles
T.T. Van, University of California, Los Angeles
M. Sawkar Mathur, University of California, Los Angeles
J. Bargar, Stanford Synchrotron Radiation Laboratory
B. Hoex, Eindhoven University of Technology, The Netherlands
W.M.M. Kessels, Eindhoven University of Technology, The Netherlands
M.C.M. Van De Sanden, Eindhoven University of Technology, The Netherlands
R. Ostroumov, University of California, Los Angeles
K. Wang, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
We report in this work the utilization of radical enhanced atomic layer deposition (RE-ALD) to synthesize ultra thin films with controlled dopant incorporation. Er-doped Y@sub 2@O@sub 3@ is a potential waveguide core material for compact optical amplifiers because Y@sub 2@O@sub 3@ allows for incorporating of a higher concentration of Er and enables a compact geometry and a larger signal admittance angle. Extended X-ray Absorption Fine Structure (EXAFS) analysis showed that Er was in the optically active trivalent state in all samples, confirmed by their X-ray absorption near-edge spectroscopy. Modeling of the EXAFS data revealed that Er@sup 3+@ is coordinated with 6 O at 0.224 and 0.232 nm. The critical inter-ionic distance between two Er@sup 3+@ was determined to be 0.4 nm, thus setting an upper limit on the Er@sup 3+@ concentration in Y@sub 2@O@sub 3@ at about three orders of magnitude higher than the Er@sup 3+@ solubility limit in the conventional SiO@sub 2@ host. X-ray diffraction (XRD) and selected-area electron diffraction patterns revealed a preferential film growth in the [111] direction, showing a lattice contraction with increasing Er doping concentration, likely due to Er@sup 3+@ of a smaller ionic radius replacing the slightly larger Y@sup 3+@. The optical properties of Er@sup 3+@ ions incorporated in Y@sub 2@O@sub 3@ were investigated by using cavity ring-down spectroscopy (CRDS), and the peak absorption cross section of Er@sup 3+@ in Y@sub 2@O@sub 3@ at 1.53-µm was estimated to be ~2.0x10@sup -20@ cm@sup 2@, about two times of that for Er@sup 3+@ in SiO@sub 2@. This is consistent with our previously reported larger effective absorption cross session of Er@sup 3+@ based on the photoluminescence yield as a function of the pump power. An important implication of this higher absorption cross section is that the population inversion can be achieved at a lower pump power and hence higher pumping efficiency.