Simulation and optical characterization of efficient light-emitting metallo-dielectric micro- and nanopillars

• Autor(a) principal: Moura, Pedro Alexandre Aparício de
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/89662
• topic: Photonics; NanoLED; Purcell effect; metallo-dielectric cavities; Internal Quantum Efficiency; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Currently there is a large boost in developing photonic technologies for computing as they promise high speed and low energy consumption. Nanoscale light sources might play a key role for such photonic integrated circuits, which may replace electronic chips one day. Recent experimental implementations include nanolasers, which typically require complex nanostructures for lasing operation, e.g. realized via photonic crystals, metallo-dielectric or plasmonic cavities. Here alternatives to nanolasers are studied - nanolight-emitting diodes (nanoLEDs). The main advantages are that these do not require high quality factor cavities needed to reach a lasing threshold, thus making nanoLEDs less sensitive to fabrication imperfections. By engineering nanoLEDs using nanocavities, the spontaneous emission rate can be increased substantially as compared with the bulk material as described by the Purcell effect. NanoLEDs using cavities smaller than the emitted wavelength, show great potential due to their unique features such as ultra-small footprint, high-speed modulation and unprecedent low energies budget. In this thesis, the optical properties of a dielectric encapsulated semiconductor AlGaAs/GaAs/AlGaAs nanopillars with or without a metal cavity will be investigated, both theoretically and experimentally. The theoretical part includes the analysis of metallo-dielectric micro- and nanopillar structures using 3D-FDTD simulations and the study of the radiative recombination taking the Purcell effect into account. The optical characterization includes the study of the emission properties using micro-photoluminescence and time-resolved photoluminescence techniques. From these results, the expected internal quantum efficiency (IQE) values are analyzed and the potential of these structures for the design of efficient nanoLED sources is discussed. The results are discussed in the perspective of the development of highly efficient nanoLEDs at room-temperature for future integrated photonics circuits.