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HL: Halbleiterphysik
HL 15: III-V semiconductors II
HL 15.1: Talk
Tuesday, March 28, 2006, 11:00–11:15, POT 51
Incorporation of N at GaAs and InAs Surfaces — •Hazem Abu-Farsakh1,2, Alexey Dick 1, and Jörg Neugebauer1,2 — 1Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany — 2Universität Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
Recently, GaAsN and GaInNAs alloys with low N content have attracted a remarkable interest for making laser diodes operating in the 1.3-1.6 µm region which is interesting for optical fiber communications. A specific problem for practical applications is the extremely low bulk equilibrium solubility of N in GaAs at typical growth temperatures. An interesting option to increase the concentration of N is the use of surface kinetics by (i) identifying GaAs and InAs surfaces with a large N solubility, and (ii) identifying conditions which prevent/reduce surface aggregation of N. We have therefore calculated the surface phase diagrams of N at GaAs and InAs surfaces using density functional theory in the GGA approximation. Based on these results, we have estimated the maximum N equilibrium concentration at various surface orientations ((110), (001)) for given temperature and chemical potentials, and compared them with recent experimental results. In addition, STM simulation of selected structures have been made and compared with available experimental images.