Au adsorption induced faceting and phase transitions of facet planes on the Si[110] zone studied by UHV-REM

Au was deposited on a cylindrical surface made in a Si(110) wafer and Au adsorption induced facet formation on the [1 (1) over bar 0] zone was studied by ultra-high vacuum reflection electron microscopy. We studied structural changes of the surfaces with orientations between the (110) and the (113) planes through the (111) plane. It was found that four high index surfaces, (441), (553), (335) and (5 5 11), in addition to low index surfaces, (110), (111) and (113), showed images with flat surfaces and with well defined reflection high energy electron diffraction patterns after deposition of 0.5 ML Au. Such high index surfaces have not been observed as flat surfaces on a clean cylindrical Si surface. They are considered to be facet planes stabilized by Au adsorption. So-called hill and valley structures were seen between some pairs of the Au adsorption induced facet planes and the (110), (111) and (113) planes. The facet planes have reversible structural phase transition at temperatures between 740 and 820 degrees C, which depend on the facet planes. It should also be noted that the formation of the facet planes depends on the substrate temperature (in other words annealing temperature after deposition of Au) and on the amount of Au deposit. The adsorption induced facet formation is a kind of self-organization of surface morphology. (C) 1998 Elsevier Science B.V. All rights reserved.