Cooperative quantum confinement of excitons bound to isoelectronic impurity complexes in Si1−xGex/Si superlattices

Abstract

Excitons bound to isoelectronic impurity complexes in strained Si_1−xGe_x/Si superlattices (SLs) grown on Si(100) substrates exhibit a novel type of cooperative quantum confinement. The small conduction‐band and much larger valence‐band offsets in this material system confine an electron much less effectively than a hole. The short‐range potential associated with isoelectronic electron traps located within the alloy layers of the SL provides an additional mechanism for localizing electrons within the wells of the SL. We use Be isoelectronic complexes to demonstrate and explore this cooperative confinement of excitons in Si_1−xGe_x/Si superlattices.