Catalytic and Chemical Properties of Atomically Clean Elemental Semiconductor Surfaces

摘要

A high vacuum catalytic reactor was developed to measure the rates of catalytic and surface chemical processes occurring during the interaction between ethanol and atomically clean germanium and silicon surfaces as a function of temperature, pressure, controlled surface contamination, and bulk semiconductor doping. Germanium powders catalyzed the steady state dehydrogenation of ethanol, and the reaction rate was determined over a wide range of experimental conditions. Atomically clean germanium surfaces abstracted oxygen from ethanol producing ethylene, hydrogen, and a non-reducible surface oxide. The dehydrogenation activity of the germanium surfaces was independent of bulk doping over the entire range investigated. Ethanol was chemisorbed much more strongly by clean silicon surfaces than germanium. Silicon surfaces were oxygenated at temperatures above 300C, in a fashion similar to germanium, by ethanol; and they possessed no steady state dehydrogenation activity. The catalytic activity of the germanium surfaces was attributed to their ability to form covalent bonds with hydrogen.