Co-doping of Er-doped SiC with oxygen : a promising way towards efficient 1540 nm emission at room temperature?

Rare-earth doped semiconductors like SiC provide potential use as light-emitting diodes or lasers. Of particular interest is erbium because of its intra 4/-shell transition at 1540 nm coinciding with the minimum absorption of optical fibers. However, the main problem is rather low intensities at room temperature. In this work, based on calculated spin-densities some of the Er-related EPR-spectra are assigned to Er-donor pairs within S=3/2 high spin states. In the light of a calculated excitation scheme, Er Si N C pairs are proposed to be responsible for the 1540 nm emission observed in n-type SiC. In comparison, the energy level for Er Si O C pairs is considerably lower. Since thermal quenching of the IR-emission is related to the position of the Er-level below the conduction band, co-doping of SiC: Er with oxygen would be very desirable, providing more intense emission at room temperature.