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HL: Halbleiterphysik

HL 3: Heterostrukturen I

HL 3.1: Talk

Monday, March 11, 2002, 10:30–10:45, H14

On the origin of carrier localization on two-dimensional GaN substitution layers embedded in GaAs — •Heidemarie Schmidt¹, Rainer Pickenhain¹, and Georg Böhm² — ¹Universität Leipzig, Fakultät für Physik und Geowissenschaften — ²Institut für Oberflächenmodifizierung, IOM, Leipzig

The optical properties of a host material can be drastically modified by embedding two-dimensional isovalent substitution layers. Such substitution layer/host material systems with efficient excitonic transitions are expected to play a crucial role for next generation optical devices. We calculate the bandstructure of the InAs/GaAs, InP/GaP, and GaN/GaAs systems by means of empirical pseudopotentials and discuss the dependence of the optical properties of the host material on the chemical and structural effects associated with the embedded two-dimensional isovalent substitution layer. By comparing the calculated electronic properties of GaN/GaAs with those of the InAs/GaAs and InP/GaP material system, we find that the GaN/GaAs system which can be regarded as an ordered GaAsN alloy has anomalous electronic properties, e.g., not only one but the two lowest GaN/GaAs-conduction bands behave like eigenstates of the GaN substitution layer [1]. We investigate the origin of the two lowest conduction band states in the GaN/GaAs system in detail and find some similarities with respect to the origin of the new (defect) levels which appear in the bandgap of GaAsN alloy material [2].

[1] H. Schmidt, R. Pickenhain, G. Böhm, to be published in Phys. Rev. B Januar 2002)

[2] L.-W. Wang et al., Phys. Rev. Lett. 80, 4725 (1998).