Structural–electronic aspects related to the near-infrared light emission of Fe-doped silicon films

Abstract

The need of efficient (fast and low consumption) optoelectronic devices has always been the driving force behind the investigation of materials with new or improved properties. To be commercially attractive, however, these materials should be compatible with our current micro-electronics industry and/or telecommunications system. Silicon-based compounds, with their matured processing technology and natural abundance, partially comply with such requirements—as long as they emit light. Motivated by these issues, this work reports on the optical properties of amorphous Si films doped with Fe. The films were prepared by sputtering a Si +Fe target and were investigated by different spectroscopic techniques. According to the experimental results, both the Fe concentration and the thermal annealing of the samples induce changes in their atomic structure and optical–electronic properties. In fact, after thermal annealing at ∼750 °C, the samples partially crystallize with the development of Si and/or β - FeSi 2 crystallites. In such a case, certain samples present light emission at ∼1500 nm that depends on the presence of β - FeSi 2 crystallites and is very sensitive to the annealing conditions. The most likely reasons for the light emission (or absence of it) in the considered Fe-doped Si samples are presented and discussed in view of their main structural–electronic characteristics.