Isolation of a metallic Si(111)7x7 surface reconstruction via separation by implanted oxygen

High-quality Si(111)7x7 surface reconstructions have been observed on (111) -oriented Si/SiO2/Si substrates, prepared via separation by implantation of oxygen, or "SIMOX," with top layer thicknesses as small as 220 Angstrom. S canning tunneling microscopy and spectroscopy data indicate that the electr ically and physically isolated top layer is electrically conducting, in con trast to that of (100) SIMOX material, which accumulates charge under typic al imaging conditions. We speculate that the 7x7 reconstruction on (111) SI MOX material is an efficient conduction channel, allowing atomic resolution imaging of the isolated Si top layer. (C) 2000 American Institute of Physi cs. [S0003-6951(00)00506-4].