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HL: Halbleiterphysik

HL 30: III-V Halbleiter II

HL 30.4: Talk

Thursday, March 29, 2001, 11:15–11:30, S16

OPTICALLY DETECTED MAGNETIC RESONANCE INVESTIGATIONS OF NATIVE DEFECTS IN LOW TEMPERATURE GROWN BY MBE GaAs — •I. Tkach¹, K. Krambrock¹, J.-M. Spaeth¹, S. Tautz², and P. Kiesel² — ¹Fachbereich Physik, Universität Paderborn, 33095 Paderborn, Germany — ²Institut für Technische Physik I, Erwin-Rommel-Str.1, D-91058 Erlangen, Germany

Experimental results obtained on GaAs grown by MBE at low substrate temperature (200 ^∘ C) using Magnetic Circular Dichroism of the Optical Absorption (MCDA) and optically detected via change of MCDA Electron Paramagnetic Resonance (MCDA-EPR) are presented. The samples after growth were prepared with lift-off technique and annealed at different temperatures from as-grown to 650 ^∘ C. The preparation with the lift-off method enables us to expose the material without the influence of the GaAs substrate. In our report emphasis is placed on the investigation of bleaching properties of As-antisite-related defects in LT GaAs . Precise MCDA-EPR and so called tagged by EPR MCDA investigations show that we deal with different As-antisite-related defects in as-grown and annealed material. A critical annealing temperature is near 400 ^∘ C. MCDA-EPR reveals an yet unknown defect in samples annealed above 450 ^∘ C which we attribute to a Ga-vacancy-related defect consistent with positron annihilation experiments.