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Semiconducting high manganese silicide (HMS) MnSi1.7 precipitates and thin films have been synthesized by ion implantation. High-resolution transmission electron microscopy (HRTEM) was employed to investigate the crystalline structures. The equilibrium phase of MnSi1.7, i.e., Mn4Si7, was synthesized in all samples. Optical absorption spectra obtained by transmission measurements demonstrated the existence of a direct band gap in all samples. The band gap energies varied ranging from 0.77 to 0.93 eV, possibly due to variation in the strain state associated with different microstructures.

We report and compare the luminescence, both photo- and electroluminescence, in the near-infrared of a wide range of rare earths (Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) doped dislocation engineered silicon light emitting devices. The rare earths are introduced using ion implantation into standard Czochralski (CZ) n-type silicon wafers pre-implanted with boron to form both the p–n junction and an engineered dislocation loop array. Rare earth internal transitions are observed in samples co-doped with Dy, Ho, Er, and Tm. We show that for each rare earth optimizing the optical activity depends critically on the rare earth implant parameters and post-implant process conditions. Room temperature operation in the 1.5 and 2.0 µm spectral regions is observed from the internal rare earth transitions in Er and Tm.

Iron-disilicide films were sputter deposited on Si(100) wafers to 300–400 nm, at substrate temperatures ranging from room temperature to 700 °C. As-deposited films were amorphous at deposition temperatures up to 200 °C, and crystalline β-FeSi2 at 300–700 °C. Amorphous films were heat-treated after deposition at 300–700 °C. They remained amorphous up to 400 °C, and transformed to crystalline β-FeSi2 at 500–700 °C. Optical absorption measurements showed that the band gap of all films is direct in nature, ranging from 0.88 to 0.93 eV. The deposition temperature was seen to affect the crystallinity of the as-deposited films and to vary their optical properties significantly. The photoabsorption coefficient, measured at 1 eV, increased from 5.6 ×104 cm-1 for amorphous films to 1.2 ×105 cm-1 for the samples deposited at 700 °C. The films crystallized by heat-treatment had a markedly different and irregular structure, resulting in their lower optical absorption.

Ion beam synthesised β-FeSi2 light emitting devices have been fabricated by ion implantation of iron into pre-grown abrupt silicon p–n junctions. Several samples were fabricated by varying the implant conditions and the junction characteristics (layer thickness and doping concentration). Light emission at ∼1.5 µm was obtained from all devices but the intensity decreased with increasing temperature. The electroluminescence quenching was found to depend on both the iron implant conditions and the characteristics of the p–n junction.