Direct imaging of a novel silicon surface reconstruction

Silicon surface reconstructions are directly observed in profile by high-resolution transmission-electron microscopy. Low-energy surface facets are formed at edges by in situ annealing of a 〈110〉 thin specimen at an ambient pressure of 10^-9 Torr. As well as 〈111〉, 〈100〉, and 〈110〉 reconstructed surfaces, extensive areas of flat 〈113〉 surface are found. By inspection of high-resolution images from the 〈113〉 surface a model involving one dimer per surface (1×{}1) unit cell is proposed, suggesting that low-energy surfaces need not be confined to high-symmetry orientations.