A zinc-related isoelectronic bound exciton in silicon

Abstract

Photoluminescence (PL), photoluminescence excitation (PLE), and photoluminescence lifetime measurements are reported for a newly-discovered optical centre in a silicon sample diffused with iron and zinc. The PL spectrum consists of two thermalizing no-phonon lines, each with sharp low energy local mode phonon replicas in addition to a broad multi-phonon sideband. The no-phonon lines, at 1059.93±0.05 and 1075.12±0.05meV, are attributed, respectively, to transitions from the spin triplet and singlet states of an isoelectronic bound exciton (IBE). Other states of the IBE are observed at 1108.4±0.5, 1110.0±0.5 and 1133.2±0.5meV in the PLE spectrum, which also shows sharp local mode phonon replicas. The energy level structure is consistent with IBE states formed by a hole and an electron subject to a large ground state valley-orbit splitting, and bound at the centre by ≈82meV.