REACTIVE CRYSTAL-GROWTH IN 2-DIMENSIONS - SILICON-NITRIDE ON SI(111)

The nitridation of the Si(111) surface by reaction with NH3 was studied by low-energy electron microscopy (LEEM), low-energy electron diffraction (LEED), and scanning tunneling microscopy (STM). Reaction layers with periodicities of (8×8), (8/3× 8) / 3), (3/4× 3) / 4), and (3 3 /4×3 3 /4) were observed depending on the temperature of nitridation and duration of electron-beam exposure. The nucleation and growth of the nitride layer on well-oriented and miscut Si(111) surfaces were observed by STM and followed in real time by video LEEM. The (8×8) nitride islands nucleate and grow in the same manner as the (7×7) domains, with the apex of the triangle pointing in the [1̄ 1̄2] direction away from the step into the upper terrace. On the miscut surface, (8×8) nitride growth proceeds with widening of the terraces and step bunching. The (3/4× 3) / 4) multiplet structure, on the other hand, nucleates randomly on comtaminated sites on the surface, or evolves directly from the (8×8) structure. © 1995 The American Physical Society.