Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 45: ZnO II

HL 45.4: Vortrag

Donnerstag, 29. März 2007, 14:45–15:00, H17

Hydrogen induced charge state alteration of Mn trace impurities in ZnO — •M. A. Gluba, F. Friedrich, and N. H. Nickel — Hahn-Meitner-Institut Berlin, Abt. Silizium Photovoltaik (SE1), Kekuléstraße 5, 12489 Berlin, Germany

The source of the natural n-type doping of ZnO is still a subject of discussion. However, both theoretical [1] and experimental work [2] show that hydrogen plays a crucial role. To elucidate the paramagnetic behavior of H in ZnO low temperature X-band electron paramagnetic resonance (EPR) measurements were performed. For this purpose EPR spectra were taken from pressurized-melt-grown nominally undoped ZnO single crystals before and after hydrogenation.

As-grown ZnO exhibits a single EPR-line at g=1.957 arising from multiple centers, one of which was identified as a hydrogen shallow donor [2]. On the other hand, post-hydrogenated ZnO shows a distincly different EPR spectrum. Besides the intensification of the hydrogen-related line additional fine and hyperfine split lines originating from ⁵⁵Mn appear. However, these features are not stable. While keeping the samples at room temperature for about four weeks the hydrogen line decays to its initial value. In the same period of time the manganese lines disappear completely. A likely mechanism for this correlation - the change of the Mn charge state due to hydrogen doping - will be discussed.

[1] C. G. Van de Walle, Phys. Rev. Lett. 85, 1012 (2000)

[2] D. M. Hofmann et al., Phys. Rev. Lett. 88, 045504 (2002)