Femtosecond pulsed laser deposition as a novel route for nanocomposite photonic materials on silicon

Femtosecond pulsed laser deposition (fs-PLD) has been investigated extensively over several decades, yet none have considered interactions between the intensely hot, high velocity plasma species ejected from a target material with a heated substrate. For this reason, the interaction of a femtosecond pulsed laser generated plasma with a given substrate is investigated in this thesis for the development novel functional materials.
The fabrication of Tm3+ and Er3+ doped silicon thin films is presented with room temperature photoluminescence peak emission wavelengths of 2.04 μm and 1.54 μm, respectively. Characterisation of these and undoped films however reveals a difficulty in engineering the materials. This approach to materials fabrication does however have potential to engineer multifunctional surfaces for a variety of applications.
A new approach to fs-PLD is therefore sought through the heating of a silicon substrate to 570 °C and ablating a rare earth doped tellurite glass target to deposit upon it. This is found to result in the sequential growth of ZnTe, Te, ZnO and rare earth doped crystallites in a modified surface layer. This is explained based upon thermochemical calculations and observations in literature. The structural characteristics of these materials are determined by scanning electron microscopy as well as transmission electron microscopy, while the crystallography is studied by selected area electron diffraction and X-ray diffraction.
Fluorescence characterisation of these surface materials formed upon silicon reveal emission from ZnO, ZnTe, Tm3+-doped crystallites and Er3+-doped crystallites. Fluorescence spectroscopy of these materials shows characteristic emission in the visible and near-infrared.