Structure Models for the Si (111) 7×7 Surface Structure

Abstract

Since the first observation of the Si (111) 7×7 structure by Schlier and Farnsworth in 1959, many structure models have been already proposed. They are, for instance, vacancy model by Lander-Morrison, chain model by Seiwatz, dislocation model by Takeishi-Hirabayashi, buckling models by Levine et al. Miller-Haneman and Chadi et al, and their modified ones. However, LEED intensity analysis was not tested for the majority of the models. Only for few models, the intensity analysis were actually carried out, but the agreement between the LEED observation and the calculated intensity was not necessarily enough.Recently, Ino proposed a new structure model which contains some scattering matter arranged in a regular triangular form with side 2a, a being the size of the substrate unit mesh. The new model was deductively obtained as a structure which satisfies a Patterson function calculated by using a mean intensity distribution of various RHEED patterns. The intensity distributions calculated from the model agreed well with that obtained not only from RHEED but also LEED patterns.A comparison and discussion among the all proposed models are given on the basis of the kinematical intensity analysis of LEED and RHEED.