Optical and magnetic resonance studies of As-impurities in AlSb: from isoelectronic point defects to planes

Strong photoluminescence (PL) has been observed and assigned to excitons fr om superlattices (SL) composed of fractional or single planes of As atoms s eparated by 8-49 monolayers (ML) of AlSb, from a single As-impurity sheet e mbedded in AlSb, and from AlSb layers uniformly doped with As. The emission ( similar to 1.40-1.62 eV) from the SLs exhibits a weak dependence on peri od but a strong dependence on the amount of As in the plane. From optically detected magnetic resonance, the g-values and strength of the exchange int eraction indicate that the SL recombination involves an exciton whose elect ron is strongly localized at the As-planes and whose hole is excluded to th e AlSb layers. This assignment is supported by ab initio total energy calcu lations of the electronic band structure. Similar PL was found from the sam ple with a single As-impurity sheet. A PL band at 1.606 eV from the As-dope d AlSb layer is ascribed to recombination of excitons bound to As-impuritie s that substitute isoelectronically on the Sb sites. (C) 1999 Elsevier Scie nce B.V. All rights reserved.