Magneto-optical and magnetic resonance investigations of DX centres in Te-doped

Abstract

DX centres in a 300 µm thick layer of Te-doped Al 0.46 Ga 0.54 As grown by liquid-phase epitaxy and removed from the substrate were investigated using magneto-optical and paramagnetic resonance techniques. A magnetic circular dichroism of the optical absorption (MCDA) in the near-infrared region was found upon photoexcitation of DX centres with a threshold of 0.6 eV, which agrees with the IR band found previously for the metastable Te 0 centres. From the MCDA-detected EPR line (g = 1.96 ± 0.02, B 1/2 = 14 mT), in which no hyperfine splitting of 125 Te is resolved, and from the onset of the MCDA band, it is concluded that the metastable Te 0 is an EMT (effective mass theory) state derived from the X-band minimum and that the infrared band is a photoionization transition to the excited X 3 conduction band minimum.

Experimental evidence for the distinction between metastability and persistence in optical and electronic properties of bulk GaAs and AlGaAs

“…Both have c harge states which are related to a large lattice relaxation 5,6 . The transfer of the DX centers by light a t l o w temperature is accompanied by a persistent photocurrent PPC 7,8 , whereas that of EL2 is related with a persistent quenching of the photocurrent PPCQ 9 . In the literature, much confusion still exists when it concerns with persistent e ects in the electronic and optical properties of a semiconductor.…”