Immobilization of Neodymium Complexes on Semiconductor Surfaces and Processing of GaAs-based Photonic Crystals

Lanthanide ion luminescence exhibits characteristic narrow emission bands ranging from VIS to NIR along with relatively long emission lifetimes which makes them attractive for applications in lighting, sensing, and display technologies. The focus of this dissertation lies on the optical characterization of newly synthesized neodymium complexes bearing phosphonate ester ligands and the fabrication of photonic crystal (PhC) cavities. Micro-photoluminescence (PL) spectroscopy is used to investigate the NIR emission bands of trivalent neodymium ions at both room and liquid helium temperatures. The emission lines of the emission band at around 890nm are labeled with the help of temperature-dependent PL measurments. PL measurements of equimolar solutions reveal information about the emission strength of the complexes with different ligand types. For light enhancement, molecules are immobilized on PhCs. The fabrication and optimization of PhCs using electron beam lithography (EBL), inductively coupled plasma reactive ion etching and selective wet etching techniques is discussed. For molecule immobilization on the PhCs several approaches are developed. In addition to drop-casting complex solutions on PhC samples, a molecule-mixed electron beam resist is investigated as an EBL-supported method. A third technique involves locating molecules on the PhC via EBL and covering them with protective SiO2. This thesis is organized as follows: Chapter 1 gives a brief introduction highlighting the motivation of the current research. The second chapter contains a comprehensive fundamental insight into the research topics on which this thesis is based. In Chapter 3 the experimental methods, the required equipment and their working principle are introduced. In the following three chapters, the main results are presented including complex synthesis, the optical characterization of neodymium complexes, PhC processing and the immobilization of the molecules on the PhCs. Finally, Chapter 7 summarizes the work.