Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.58: Poster

Tuesday, March 15, 2011, 18:00–21:00, P3

Donor-acceptor pair recombination in ZnO — •Marko Stölzel, Alexander Müller, Stefan Müller, Gabriele Benndorf, Michael Lorenz, Holger von Wenckstern, and Marius Grundmann — Universität Leipzig, Institut für Exp. Physik II, Abteilung Halbleiterphysik, Linnéstr. 5, 04103 Leipzig

ZnO is due to its material properties an interesting semiconductor for electronic and optoelectronic applications. However, the difficulties in growing stable p-type ZnO have inhibited the commercial fabrication of devices such as LEDs. Reported acceptor activation energies are usually well above 100 meV. Therefore, only a small fraction of such acceptors would be ionized at room temperature in p-type ZnO.

In this study we report on a donor-acceptor pair (DAP) recombination at 3.325 eV at 2 K found in a nominally undoped ZnO film grown by pulsed-laser deposition on a ZnO:Al buffer layer on a-sapphire.

The sample has been investigated by temperature-dependent time-integrated and time-resolved photoluminescence (PL) as well as electrical investigations. The PL measurements show a clear shift of the DAP recombination to higher energies with increasing excitation power. The transients exhibit a clear non-exponential behavior typical for DAP recombination and were described by the model of Thomas et al. [1] yielding the donor concentration, the Bohr radius of the donor and the pair distance. The determined donor concentration is in good agreement with that obtained from electrical measurements. From that we deduce an acceptor binding energy between 60 and 80 meV.

[1] D. G. Thomas et al. Phys. Rev. 140, A202 (1965)