Photoluminescence of ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ multiple quantum well structures containing δ-doping superlattices

${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ multiple quantum well structures containing nipi-δ-doping superlattices were grown by low-pressure-metalorganic vapor phase epitaxy. Optical properties of such structures have been studied by photoluminescence (PL) as a function of temperature and incident excitation power. A critical temperature, below which PL emissions come from spatially indirect transitions, is defined. The indirect transitions occur between levels inside the GaAs quantum well (QW) and inside the inverted V-shape potential in the ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ barriers. Above the critical temperature, a direct transition, which involves levels only inside the GaAs QW, is the dominant transition in the PL spectra. Theoretical calculations helped to understand the PL peak energy behavior with temperature and confirmed the indirect character of the emissions below the critical temperature. The indirect character was also identified through PL measurements as a function of the incident excitation power. The dependence of the critical temperature both on the samples’ structure and on the incident excitation power is discussed.