AVS 52nd International Symposium
    Thin Films Thursday Sessions
       Session TF-ThM

Paper TF-ThM2
Controlled Doping and Photoluminescence Properties of Er-doped Yttrium Oxide Thin Films

Thursday, November 3, 2005, 8:40 am, Room 306

Session: Optical Thin Films
Presenter: T.T. Van, University of California, Los Angeles
Authors: T.T. Van, University of California, Los Angeles
J. Bargar, Stanford Synchrotron Radiation Laboratory
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
Though silica has traditionally been used as the Er host in fiber amplifiers, it is an unsuitable host in small, compact amplifiers due to its low solubility for Er. One potential host is Y@sub 2@O@sub 3@. Its high refractive index allows for a compact geometry and large signal admittance angle, thus higher pumping efficiency. Due to the similarities in crystal structure and lattice constant between Y@sub 2@O@sub 3@ and Er@sub 2@O@sub 3@, a much higher Er concentration can be incorporated Y@sub 2@O@sub 3@, compared to that in silica. Er-doped Y@sub 2@O@sub 3@ thin films were synthesized by radical-enhanced atomic layer deposition (RE-ALD) at 350°C, using metal beta-diketonates as the metal precursors and O radicals as the oxidant. The deposition of Y@sub 2@O@sub 3@ was alternated with Er@sub 2@O@sub 3@ and the Er doping level was effectively controlled by varying the ratio of Y@sub 2@O@sub 3@:Er@sub 2@O@sub 3@ cycles. The films were polycrystalline with a preferential growth in the (111) plane. Room-temperature PL at 1.54 µm was observed in a 500-Å Er-doped (6.6 at.%) Y@sub 2@O@sub 3@ film, showing well-resolved Stark features indicating the proper incorporation of Er in Y@sub 2@O@sub 3@. The result is very promising, since the film is fairly thin and no annealing at high temperature is needed to activate the Er ions. Extended X-ray absorption fine structure (EXAFS) analysis showed an identical Er local environment for samples with 6-14 at.% Er, suggesting the PL quenching at high Er concentration (>12 at.%) is likely dominated by ion-ion interaction and not by clustering. The effective absorption cross section for Er in Y@sub 2@O@sub 3@ was estimated to be on the order of 10@super -18@ cm@super 2@, about three orders of magnitude larger than that in the silica host. These results validate Y@sub 2@O@sub 3@ as a promising Er host and demonstrate that RE-ALD is a viable technique for synthesizing thin films with well-controlled dopant incorporation.