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Structural characterization of Indium-acceptor complexes in ZnO by PAC
|Muhammed Türker , Peter Reichert , Manfred Deicher , Herbert Wolf , Thomas Wichert|
Universität des Saarlandes, Technische Physik, Saarbrücken, Germany
|Difficulties in achieving reliable and reproducible p-type ZnO hamper its use for optoelectronic applications in the blue and UV region. A solution to the challenge of p-type doping might be the theoretically proposed codoping  or cluster doping  of donors and acceptors. The former method has been confirmed by Hall effect measurements in the case of In-N codoping of ZnO-films . From theory the formation of In-acceptor complexes is predicted, thereby enhancing the solubility of the acceptor.
On an atomic scale, these defect complexes are distinguished by characteristic electrical field gradients (EFG) at the lattice site of the indium donor. Using perturbed γγ angular correlation spectroscopy (PAC), the presence of these EFG is detected at the site of the radioactive probe atom 111In/111Cd . After applying different co-doping procedures (diffusion and/or implantation) in case of the combinations In-N and In-P, the formation of In-acceptor complexes has indeed been observed via the occurence of additional EFG besides the EFGlattice.
Each complex is characterized by two slightly different EFG as is expected because of the wurtzite structure of ZnO and the different nearest neighbor distances along the c axis and in the basal plane. The efficiency of the different co-doping procedures and their dependencies on the diffusion and annealing conditions will be discussed.
This work has been supported by the Bundesministerium für Bildung und Forschung (BMBF) under Contract No. 05 KK7TS2.
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Presentation: Oral at E-MRS Fall Meeting 2009, Symposium C, by Muhammed Türker
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-06 16:09 Revised: 2009-08-06 22:34