Formation of Three-Dimensional Silicon Mounds on the Si(111) 7 × 7 Surface Using the Tip of a Scanning Tunneling Microscope : Surfaces, Interfaces, and Films

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Truncated triangular silicon pyramids are fabricated one by one on the Si(111) 7 x 7 surface in the temperature range from 400℃ to 500℃. Two types of three-dimensional (3D) silicon mounds are fabricated with a mirror symmetry against the [101] direction. One type consists of normal stacking mounds with {311} and {221} on the side facets and a (111) on the top surface. The other type consists of silicon mounds with a stacking fault at the interface between the silicon mounds and the substrate surface, which have {311} facets, {331} facets and a (111) facet. Normal stacking mounds are produced with a probability of 75%. Silicon mounds with a stacking fault are produced with a probability of 25%. The difference in the formation energy between normal stacking mounds and silicon mounds with a stacking fault is about 0.07eV per 1 x 1 unit cell at 500℃. Silicon mounds are fabricated with large tunneling currents and sample bias voltages near 0V. During the production of silicon mounds, the scanning tunneling microscope (STM) tip moves away from the substrate surface by about 26nm. The production rates of silicon mounds are 120 ± 10s^<-1> at 440℃, 220 ± 20s^<-1> at 465℃ and 570 ± 80s^<-1> at 485℃. The activation energy required for the production of silicon mounds is 1.3 ± 0.1eV and the pre-exponential factor is 4 x 10^<11±1> s^<-1>
社団法人応用物理学会の論文
2001-08-15