EVIDENCE FOR THE LEADING ROLE OF THE STACKING-FAULT TRIANGLE IN THE SI(111)1X-1-]7X7 PHASE-TRANSITION

In situ scanning-tunneling-microscopy (STM) observations at temperatures up to 600°C provide atomic-scale evidence, demonstrating that the formation of the stacking-fault (SF) half-unit plays the leading role in the growth of 7×7 reconstructed domains of Si(111) surfaces from the 1×1 phase upon supercooling. The concept of the SF leading role accounts for the fact that all of the 7×7 reconstructed areas on Si(111) supercooled surfaces form triangular domains with vertices pointing in 1̄ 1̄2 directions. The STM data suggest that the formation of the SF half-unit involves the construction of dimer chains and corner holes. A similar leading role of the SF half-unit is also deduced to be fundamental for the growth of 5×5 or 9×9 metastable structures. © 1995 The American Physical Society.