eprintid: 1420212 rev_number: 35 eprint_status: archive userid: 608 dir: disk0/01/42/02/12 datestamp: 2014-06-06 15:31:16 lastmod: 2021-07-27 23:58:02 status_changed: 2014-06-06 15:31:16 type: thesis metadata_visibility: show item_issues_count: 0 creators_name: Shah, M title: Excitation Mechanisms in erbium-doped silicon-rich silicon oxide ispublished: unpub divisions: UCL divisions: A01 divisions: B04 divisions: C05 keywords: Erbium, Silicon rich silicon oxide, Rate equations, Silicon nanocrystal note: Permission for digitisation not received. abstract: Since the invention of the first silicon transistor in 1947, the electronics industry has grown at a rapid rate, famously predicted and guided by Moore’s law. However, it has recently become apparent that satisfying Moore’s law is becoming increasingly difficult; we are now approaching the fundamental limits of device miniaturization and device speed, and alternative solutions for this problem are continuously being pursued. Over the past couple of decades, silicon photonics has emerged as a promising alternative solution. By carrying data through photons instead of electrons, many of the problems faced in an electronic device become irrelevant in an equivalent photonic device. The challenge of silicon photonics is to demonstrate lasing in a material that is compatible with existing CMOS processing technology, namely silicon. Light emission from silicon, however, is very inefficient, due to its indirect electronic bandgap. Silicon nanostructures, on the other hand, exhibit far higher light emission efficiencies, which has been attributed to quantum confinement effects. Erbium is one of the most interesting rare earth impurities for optical functionality, as it emits photons at 1.54µm, the wavelength that corresponds to minimum attenuation in silica fibres. However, erbium has a relatively low excitation cross section, and narrow excitation bands, necessitating expensive lasers for amplifier operation. It has been found that, by co-doping erbium with silicon-nanocrystals (Si-ncs), far higher excitation efficiencies of erbium can be attained, along with broadband excitation, through energy transfer from excited Si-ncs. To date, a clear understanding of the physics involved in the excitation mechanism is lacking. In this thesis, I identify erbium excitation processes in the Er doped silicon rich silicon oxide material, through photoluminescence (PL) spectroscopy. In particular, time resolved decay data of erbium emission is analysed through exponential fitting and rate equation modelling. The significance of Purcell enhanced radiative emission, and Er ion-ion interactions are highlighted. Furthermore, a characterisation study of Er doped silicon rich silicon oxide thin films will be carried out, revealing the significance and differences between defect, Si- nanocluster, and Si-nanocrystal sensitisation of Er ions. The prospects of device fabrication will also be discussed. date: 2014-03-28 vfaculties: VENG thesis_class: doctoral_md_only language: eng thesis_view: UCL_Thesis commissioning_body: University College London verified: verified_manual elements_source: Manually entered elements_id: 932006 lyricists_name: Shah, Miraj lyricists_id: MSHAH66 full_text_status: none pagerange: ? - ? pages: 206 institution: UCL (University College London) department: Electronic and Electrical Engineering thesis_type: Doctoral editors_name: Kenyon, AJ citation: Shah, M; (2014) Excitation Mechanisms in erbium-doped silicon-rich silicon oxide. Doctoral thesis , UCL (University College London).