Study On Synthesis And Application Of Metal Nanoparticle - Silicon Nanowires Composite Structures

Nanomaterials have become the research focus due to their exceptional properties and applications in recent years. Silicon nanowires (SiNWs) are widely used as nanoscale building blocks for high-performance devices such as nanoelectronics, sensors, solar cell and lithiumion battery owing to their unique structural, electrical, optical, and thermoelectric properties. In this thesis, SiNWs fabricated by metal assisted chemical etching method are used as a template to prepare metal-SiNWs composite nanostructures. Taking advantage of composite structure with larger specific surface area and unique conductance, hydrogen peroxide sensor and photoelectrochemical solar sell are designed and then tested. Main results obtained are described as follows:1. SiNWs are fabricated by metal assisted chemical etching method. The results show that high purity SiNWs with the diameter in the range of 50–300 nm are readily obtained. The lengths of SiNWs can be adjusted through changing the etching period. The crystal structure and doping type of SiNWs can be chosen by using required silicon substrate. Beside, SiNWs are much rougher and the growth direction of SiNWs could be controlled through optimizing the concentration of etching solution.2. The ordered H-terminated SiNW arrays via metal assisted chemical etching method were decorated through chemical plating the silver nanoparticles to form composite structures. We fabricated a hydrogen peroxide sensor using this silver nanoparticles-SiNWs composite structure. The results of electrochemical experiments reveal that such constructed sensor has a fast amperometric sensing, low detection limit and wide linear responding range as well as high sensitivity due to its unique conductance and more active sites per unit area. Owing to its favorable catalytic ability, this type of composite structure is very promising for the future development of non-enzymatic sensors of hydrogen peroxide.3. The ordered H-terminated SiNW arrays via metal assisted chemical etching method are decorated with copper particles via chemical plating. The photocurrent of the copper particles decorated SiNWs composite structure is measured and the dramatic enhancement of the photocurrent is observed. The enhanced photocurrent of the composite structure with the copper deposition time of 3 min is more than 20 times larger than that of initial SiNWs arrays. The results imply that copper particles decorated SiNWs composite structures are promising hybrid materials for solar cells with excellent energy conversion efficiency.