Magnetophotoluminescence spectroscopy of AlGaP-based neighboring confinement structures

Abstract

Magnetophotoluminescence (PL) spectroscopy with field strengths of up to 40 T have been carried out on tensilely strained AlGaP-based neighboring confinement structures (NCS's), consisting of adjacent AlP and GaP quantum wells sandwiched between AlGaP barrier layers. With increasing magnetic field, an anomalous redshift of PL peak energy and an anomalous reduction of PL intensity, both of which were previously reported for AlP/GaP superlattices, were clearly observed in unstrained NCS's. As an unstrained NCS is a nonperiodic structure, this result reveals that folded conduction bands in superlattices are not important for this phenomenon and that localization of excitons is likely essential. Introduction of tensile strain to an NCS was found to drastically modify magnetic-field dependence. Above a certain magnetic-field strength, the anomalous behavior stopped and a spectral blueshift and an increase of PL intensity with increasing magnetic field were observed. A competition between the confinement by magnetic field and the degree of exciton localization would be the key to explaining the unique magnetic-field dependence of PL spectra of AlGaP-based NCS's.