Manifestation of A(+) centers in the luminescence of two-dimensional GaAs/AlGaAs structures

Photoluminescence of GaAs/AlGaAs multiple-quantum-well structures incorporating positively charged beryllium-impurity shallow-level acceptors (the so-called A(+) centers) was investigated. A novel luminescence line, which originated from radiative recombination of free electrons with A(+) centers, was observed. It was shown that its spectral position is determined uniquely by the binding energy of A(+) centers. It was also ascertained that the binding energy of A(+) centers increases with a decrease in the quantum-well width when the latter is comparable to the radius of A(+) centers.