Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 40: SiC I

HL 40.3: Talk

Thursday, March 11, 2004, 15:45–16:00, H15

Deep Levels of Gadolinium in Silicon Carbide — •Gunnar Pasold¹, Fanny Albrecht¹, Christian Hülsen¹, Rainer Sielemann², Wolf Dietrich Zeitz², and Wolfgang Witthuhn¹ — ¹Friedrich-Schiller-Universität Jena, Institut für Festkörperphysik, Max-Wien-Platz 1, 07743 Jena — ²Hahn- Meitner- Institut Berlin, Glienicker Straße 100, D-14109 Berlin

Epitaxial layers of hexagonal silicon carbide (SiC) were doped with the radioactive isotope ¹⁴⁹Gd by recoil-implantation at the HMI (Berlin). Deep Level Transient Spectra (DLTS) were taken, repeatedly, during the elemental transmutation ¹⁴⁹Gd → ¹⁴⁹Eu (T_{0.5ex 1−0.1em/−0.15em 0.25ex 2}=9.5 d)

Spectra taken on p-type SiC reveal two deep levels (E_T=E_V+0.94±2 eV and E_T=E_V+0.45±1 eV), undergoing a decrease in concentration with a half-life of 11±1 d identifying them as Gd correlated. Whereas the deeper one has been found in 4H and 6H-SiC, the lower one is observable in the 4H polytype only.

Deep levels with increasing concentrations indicating levels caused by the daughter element Eu were not observed in the part of the band-gap of SiC investigated. N-type SiC samples implanted with ¹⁴⁹Gd show no time dependent deep level concentrations.