Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 41: GaN: preparation and characterization II
HL 41.10: Vortrag
Donnerstag, 26. März 2009, 12:15–12:30, BEY 154
Role of the parasitic Mg3N2 phase in post-growth activation of p-doped Mg:GaN — •Björn Lange, Christoph Freysoldt, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung, 40237 Düsseldorf, Germany
A critical issue in further improving the efficiency of modern white light-emitting diodes is the rather limited p-type conductivity achievable in GaN. The limited doping efficiency is a direct consequence of the low solubility of Mg in GaN due to the formation of the parasitic Mg3N2 phase. While the presence of this phase is well known and often unavoidable its consequences on the acceptor activation mechanism (H codoping with subsequent H removal) have not been studied so far. We have therefore studied the possibility to exploit these Mg3N2 inclusions as potential hydrogen traps by means of DFT calculations. For this, Mg3N2 has been modeled in the anti-bixbyite structure. The calculated structural properties are in good agreement with available experimental data. Based on these studies hydrogen has been explored in various positions and charge states. Our results show significantly higher H solubilities compared to GaN. Further a strongly bound N-H complex is identified which is more stable than the Mg-H complex in GaN. The implications for Mg activation in Mg:GaN above the Mg solubility limit will be discussed.