Thallium‐belated isoelectronic bound excitons in silicon. A bistable defect at low temperatures

Abstract

AbstractDetailed investigations are reported on the luminescence spectra of thallium related isoelectronic excitons in silicon, which yield a complete picture of this most unusual luminescence system. The luminescent defect exists in two different configurations, which are able to transform into each other in the temperature range from 10 to 20 K. The stress and Zeeman experiments reveal that the low temperature configuration has trigonal symmetry, whereas the high temperature form of the center is aligned along the [100] directions. Time resolved measurements of the luminescence lines lead to a detailed model for the mechanism of reorientation. In the defect ground state the trigonal symmetry is lowest in energy. The capture of a hole or an exciton changes the relative energies in such a way that now the [100] configuration is energetically favoured.