Regensburg 2007 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 45: ZnO II
HL 45.13: Talk
Thursday, March 29, 2007, 17:15–17:30, H17
Investigation of complex formation in pulsed-laser deposited Sb-doped ZnO thin-films — •Felice Friedrich and N. H. Nickel — Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik (SE1), Kekuléstraße 5, 12489 Berlin, Germany
Antimony (Sb) as group V element is a doping candidate for p-type ZnO. However, because of its large atomic size theory predicts that formation of a defect complex is more favorable. Growth temperature might play a critical role in this process. In this study the influence of Sb concentration and deposition temperature on the structural and vibrational properties of Sb-doped ZnO thin-films was investigated.
The samples were grown by pulsed laser deposition (PLD) on MgO substrates. Ceramic targets were produced from ZnO and Sb2O3 powder (0-2 at.% Sb). A XeCl excimer laser operating at a fluence of 1.5 J/cm−2 was used for the deposition process. The deposition temperature was varied between 450-800∘C. The samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray scattering (EDX) and Raman backscattering spectroscopy.
Firstly, it is observed that a higher Sb concentration leads to a reduced film thickness. Raman measurements show that this is accompanied by a deterioration of the ZnO crystallinity. Secondly, a surprising change of the Raman spectra was observed at a temperature of 600∘C. Below this temperature additional Raman modes are observed at 530, 575 and 700 cm−1. Above 600∘C the mode at 530 cm−1 is strongly suppressed. These results will be discussed in terms of the temperature-dependent formation of Zn-Sb-O complexes.