Erbium-Doped Silicon-Germanium Nanowires: Structure and Photophysics

Crystalline alloys and layered structures comprised of silicon (Si) and germanium (Ge) possess a number of fundamentally-useful properties that translate into significant advantages in state-of-the-art device platforms. Fabricating these structures into a nanowire geometry adds the perspective of dimensional confinement to their investigation; furthermore the incorporation of erbium ions (Er3+) into these semiconductors is a promising method to prepare electronic devices with efficient optical functions since the 4I13/2→ 4I15/2luminescence transition at 1.54 μm from Er3+lies at a transmission maximum for silica-based waveguides. Depending on composition, bonding, and local structure, the presence of Er3+ into these nanowires can enhance the photophysical utility of the SiGe. This presentation outlines a strategy designed to fabricate a family of SiGe nanowire platforms that incorporate the rare earth ion erbium (III) into a given structure. By probing the effect of average erbium location in the structure along with its first coordination sphere, we propose to elucidate and tune the optical behavior of these Group IV nanostructures grown via a bottom-up synthetic process. The fundamental issue of size dependent charge carrier confinement along the width of the wire is an intriguing tunable parameter to be explored here as well. A number of experimental tools will be described which determine the structure and physico-chemical characteristics of the above. These include scanning electron microscopy (SEM), conventional TEM imaging, high resolution transmission electron microscopy (HREM), energy dispersive x-ray analysis (including mapping), extended x-ray absorption fine structure measurements (EXAFS), vibrational spectroscopies (micro- Raman), as well as photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies.