Properties modification of chalcogenides by various external stimuli and the applications

Chalcogenides are fascinating materials with striking properties. Since the emergence in the 1960s, chalcogenides have been extensively studied for their low processing temperature, wide transparency window in mid-infrared, a wide range of photo-induced phenomena, as well as high linear and nonlinear refractive indices. They have been used in various applications such as phase-change memories, solar cells, sensors, holographic information storage, micro lenses, all-optical switching, and laser written waveguides, etc. Moreover, the chalcogenides also provide a platform for fundamental investigations of light-matter interactions in nanophotonics structures, such as photonic crystal and even metamaterial structures. Taking into account the essential task of enlarging the class of materials for modern science and technology as well as pursuing a deeper understanding of the properties of chalcogenides, the main theme of this dissertation is to explore the possible methods to achieve controllable and optimized modifications of the fundamental properties of chalcogenides. The first kind is about the structural modifications through light exposure. The shape changes of the thin film are created when exposed to light pattern. We then investigate the mechanisms of photo-induced surface relief formation. We derive a generalized model to explain the spatial and temporal evolution of photoinduced surface structure in photosensitive amorphous thin films. The model describes these films as an incompressible viscous fluid driven by a photoinduced pressure originating from dipole rearrangement. This derivation requires only the polarizability, viscosity and surface tension of the system. Using values of these physical parameters, the validity of the model is checked by fitting to experimental data of As2S3 and demonstrating good agreement. Another way of modifications is achieved by the doping of silver nanoparticles. We also achieve the in-situ and uniform generation of Ag nanoparticles in chalcoiii genide solution using laser ablation. Ag-doped chalcogenide films are fabricated by spin-coating the resulting solution. The prepared solution and films are analyzed using transmission electron microscopy, dynamic light scattering and UV-vis spectroscopy to investigate particle shape and size distributions. Uniform doping has been achieved. The kinetics of Ag-photodissolution into As-S glass films are investigated using ellipsometry. Increased refractive indices of the films upon near bandgap light irradiation have been measured. Besides the uniform doping of nanoparticles, we are able to incorporate a variety of ions into chalcogenide glassy matrices using in-situ wet chemistry processing. Various chlorides are incorporated into chalcogenide matrices, leading to multifarious property changes, such as absorption and refractive indices of the chalcogenides. In addition, we also explore modifications through photonic crystals. We use complementary metal-oxide-semiconductor (CMOS) processed silicon photonic crystals with angstrom surface roughness to spatially confine the solution processed arsenic sulfide and achieve controllable modulations of chalcogenides emission. A planar emitter array of chalcogenides is fabricated based on this novel periodic hetero-structures of semiconductor.