Electronic Properties of Nanoscale Metal/Silicon Interfaces and of Low-Dimensional Metal Clusters on Silicon Surfaces under Electrochemical Conditions

点击翻译按钮获取中文摘要

The project will first be concerned with the preparation and investigation of the electronic properties of nanoscale metal / n-Si (111), (110), and (100) interfaces for metal cluster, i. e. contact, diameters below 20 nm, preferably between 0.3 and 5 nm. Co, Pb, Cu and Au clusters as examples for magnetic/non - magnetic metals and systems with Nernst potentials below, around, and above the n-Si flatband potentials shall be investigated. Based on these results, the electronic properties of metal cluster/n-Si interfaces (at electron accumulation or depletion in the n-Si space charge layer) shall be exploited to precisely adjust the coupling of the electron system of individual metal clusters to their n-Si substrate. Thus, the electronic properties of individual, low-dimensional metal clusters due to a variation in the electronic coupling to a substrate shall be studied. Preparation and all investigations will be performed in-situ at solid/liquid interfaces at utmost cleanliness conditions, in electrolytes using anions which do not adsorb specifically, in deaerated electrolytes, and in the dark . The preparation of metal clusters will be achieved by localized and delocalized electrodeposition. The techniques applied for the investigations will be in-situ Scanning Tunneling Microscopy (STM), in-situ Distance and Voltage Tunneling Spectroscopy (DTS and VTS), in-situ electron transport measurements utilizing quantized conductance channels between tunneling microscope tip and metal cluster, as well as theoretical modelling of the space charge layer underneath the nanoscale metal clusters and of electronically isolated metal clusters. A comprehensive understanding of the electronic properties of individual nanoscale Schottky contacts shall be derived, interaction effects shall be investigated by studding different ensembles of a few nanodiodes fabricated with denned size and distances by localized electrodeposition, and the applicability of the thermionic emission model shall be tested by appropriate calculations of current/voltage curves. The effects of various adsorbed molecules on the measurements shall be studied by choosing several model molecules. Electronic properties of single metal clusters at denned, but variing electronic coupling to their n-Si substrate shall be investigated by in-situ tunneling spectroscopy, eventually in non-aqueous electrolytes which provide an increased double layer range available for voltage tunneling spectroscopy. Major impacts of the results of this project are expected in the fields of, e. g., nanoelectronics, catalysis, or nanoscale sensor applications.