Native defect levels in ternary compound Tl6I4S single crystals were studied by low-temperature photoluminescence (PL) and photoconductivity (PC) measurements. From the PL measurements, a broad emission band centered at 1.64 eV was observed at low temperatures. The peak can be decomposed using two standard Gaussian functions to reveal two emission bands at 1.55 and 1.66 eV. The PL peak at 1.55 eV is attributed to donor-acceptor pair recombination between a sulphur vacancy (VS) deep donor (Ed=0.57eV) and an antisite defect (SI) shallow acceptor (Ea=20meV). The 1.66-eV emission band is attributed to self-activated luminescence involving a defect complex and is described using a configuration coordinate model. Within this framework, the 1.66-eV emission band is associated with a S vacancy donor bound to a Tl vacancy acceptor that forms a VS-VTl Schottky pair. The photoconductivity spectra show the presence of a deep donor level located at 0.46 eV below the conduction-band edge, in good agreement with that measured by PL spectroscopy.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jul 18 2014|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics