| A fundamental strategy is developed in this dissertation to enhance the light-matter interaction of ultra-thin films based on a strong interference effect in planar nanocavities, and overcome the limitation between the optical absorption and film thickness of energy harvesting/conversion materials. This principle is quite general and is particularly useful for the development of atomically-thin energy harvesting/conversion devices.;This dissertation systematically investigated the enhancement introduced by nanocavities, including the theoretical design of the nanocavities, experimental validation of the enhanced light-matter interactions, and application development based on this strategy.;In Chapter 2, the nanocavities are theoretically designed for different ultra-thin material systems. Phasor diagrams and the concept of topological darkness are introduced to better understand the design.;In Chapter 3, the enhanced light-matter interaction is validated experimentally. Stronger absorption is achieved and confirmed by the stronger photoluminescence signal.;In Chapter 4, an optoelectronic application of single-crystalline germanium nanomembrane photodetectors on foreign nanocavities was developed with field effect and spectral selectivity.;This dissertation aims to analyze the both the strength and the limit of this strategy based on nanocavities and paves the way towards miniaturization of optoelectronic devices. |
