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A clean Si(100) surface is amorphized by Ar+-ion bombardment. The amorphous layer consists of grains of 0.75–1.6 nm in diameter. Solid phase epitaxy (SPE) processes of the amorphous surfaces are investigated “in situ” using ultra-high vacuum tunneling microscopy. The surface morphology during thermal annealing is affected by the Ar+-ion dose. For a lightly dosed case, (2 × 1) domains surrounded by amorphous regions consisting of grains are observed at 245°C which indicates the onset of SPE. It is found that the surface crystallizes and is smoothened in a layer-by-layer mode. As the temperature increases, the surface roughness is greatly reduced and the whole surface showed (2 × 1) reconstruction at 450°C. For a high-dose case, both (2 × 2) and c(4 × 4) reconstructions are observed in limited areas surrounded by amorphous regions during annealing at around 620°C. Pyramidal structures are observed on a (2 × 1) reconstructed surface during annealing at 830°C. The step structure of the pyramidal structure is clarified.

In this paper we discuss three experiments on silicon (100) and (111) surface at high temperature obtained with an ultra-high-vacuum scanning tunneling microscope (UHV-STM). First, the initial stage of the crystalization process has directly been investigated on the Si(111) surface at a phase transition temperature of about 860°C. (7 × 7) domains nucleated from the step edges and expanded towards inner regions of the terraces, and the steps become straight [ 1 ¯ 1 ¯ 2 ] steps. Second, the high-temperature nano-fabrication method has been applied to Si surfaces. We succeeded in creating a hexagonal pyramid and a crater on the Si(111) surface, and a quadrangular pyramid on the Si(100) surface at 600°C. (5 × 5) domains can be observed on narrow terraces due to the relaxation of surface energy. Finally, we attempted to deposit gold (Au) atoms on silicon surfaces. Au atoms deposited on a high-temperature silicon surface migrated to the observation area while forming 5 × 1 structures. Then the Au atoms diffused into the bulk structure of silicon, and silicon (7 × 7) domains covered the surface again.