Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 92: Poster Session: II-VI Semiconductors & ZnO and related Materials

HL 92.9: Poster

Donnerstag, 29. März 2012, 16:00–19:00, Poster D

Ab initio study of ZnO dual doping with Ag and N acceptors in the presence of H — Oksana Volnianska and •Piotr Boguslawski — Institute of Physics PAS, al. Lotnikow 32/46, 02-668 Warsaw, Poland

In spite of considerable recent effort in the last years, stable and efficient p-doping of ZnO is not satisfactorily solved yet. Recently, good results were obtained by using Ag [1] and N [2], or the dual doping with both species [3]. Here, we investigate theoretically efficiency of ZnO doping with Ag and N shallow acceptors, which substitute respectively cations and anions. First principles calculations indicate a strong tendency towards formation of nearest neighbor Ag-N pairs and N-Ag-N triangles. Binding of acceptors in driven by the formation of quasi-molecular bonds between dopants, and has a universal character in semiconductors. In the considered case, the Ag-N binding energy is higher than that of both Ag-Ag and N-N pairs, which are more distant. The pairing increases energy levels of impurities in the band gap, and thus lowers doping efficiency. In the presence of donors, pairing is weaker or even forbidden. However, hydrogen has a tendency to form clusters with Ag and N, which favors the Ag-N aggregation and lowers the acceptor levels of such complexes.

[1]. H.S. Kang et al., App. Phys. Lett. 88, 202108 (2006); E. Kaminska et al., in Proc. ICPS 2008, p.120. American Institute of Physics.

[2] J. M. Bian et al., Appl. Phys. Lett. 85, 4070 (2004); Z. P. Wei et al., Appl. Phys. Lett . 89, 102104 (2006).

[3]. A. Krtschil et al., Appl. Phys. Lett. 87, 262105 (2005).