Effect of thermal annealing on the photoluminescence of structures with InGaAs/GaAs quantum wells and a low-temperature GaAs layer $\delta$-doped with Mn

The effects of isochronal thermal annealing (at 325–725$^\circ$C) on the radiative properties of InGaAs/GaAs nanoheterostructures containing a low-temperature GaAs layer $\delta$-doped with Mn grown by laser deposition are studied. A decrease in the photoluminescence intensity and increase in the ground transition energy are observed upon thermal impact for quantum wells located near the low-temperature GaAs layer. The distribution of Mn atoms in the initial and annealed structures is obtained by secondary-ion mass spectrometry. A qualitative model of the observed effects of thermal annealing on the radiative properties of the structures is discussed; this model takes into account two main processes: diffusion of point defects (primarily gallium vacancies) from the GaAs coating layer deep into the structure and Mn diffusion in both directions by the dissociation mechanism. Magnetization studies show that, as a result of thermal annealing, an increase in the proportion of the ferromagnetic phase at room temperature (presumably, MnAs clusters) in the low-temperature GaAs coating layer takes place.