Semiconductor quantum dots and metal nanoparticles feature very strong light-matter interactions, which has led to their use in many photonic applications such as photodetectors, biosensors, components for telecommunications etc.Under illumination both structures exhibit collective electron-photon resonances, described in the frameworks of quasiparticles as exciton-polaritons for semiconductors and surface plasmon-polaritons for metals.To date these two approaches to controlling light interactions have usually been treated separately, with just a few simple attempts to consider exciton-plasmon interactions in a system consisting of both semiconductor and metal nanostructures.In this work, the exciton-polaritons and surface \\plasmon-polaritons are first considered separately, and then combined using the Finite Difference Time Domain numerical method coupled with a master equation for the exciton-polariton population dynamics.To better understand the properties of excitons and plasmons, each quasiparticle is used to investigate two open questions - the source of the Stokes shift between the absorption and luminescence peaks in quantum dots, and the source of the photocurrent increase in quantum dot infrared photodetectors coated by a thin metal film with holes. The combined numerical method is then used to study a system consisting of multiple metal nanoparticles close to a quantum dot, a system which has been predicted to exhibit quantum dot-induced transparency, but is demonstrated to just have a weak dip in the absorption. / <p>QC 20120417</p>

[pt] O funcionamento de detectores fotocondutivos se baseia na geração de corrente elétrica por fotoexcitação de portadores de carga. Neste trabalho, estudamos os diversos processos que contribuem para a geração de corrente em fotodetectores intrabanda (BC) e construímos um método de investigação para revelar, dentre as diferentes possibilidades, os processos que resultam na emissão eletrônica em um dispositivo concreto. Uma vez estabelecida uma metodologia, passamos ao estudo de um caso particular: um fotodetector baseado em pontos e poços quânticos acoplados, com picos de absorção no infravermelho médio. Através da comparação de espectros de absorção e fotocorrente, medidos por espectroscopia de transformada de Fourier, e de simulações computacionais para o cálculo das forças de oscilador, indicamos as transições óticas e os processos de transporte eletrônico envolvidos na fotocondutividade do dispositivo. / [en] The operation of photoconductive detectors is based on the generation of current through photoexcitation of charge carriers. In this work, we study the various processes that contribute to the generation of current in intraband (CB) photodetectors and build a method of investigation to reveal, among the different possibilities, the processes that actually result in electron emission in a particular device. After establishing a methodology, we apply it to a case study, more specifically, a dot-in-a-well (DWELL) photodetector with absorption peaks in the mid-infrared. By comparing absorption and photocurrent FTIR spectra as well as oscillator strength calculations performed by a computer simulation of the structure, we have approached the optical transitions and electron transport processes involved in the device s photoconductivity.