EXTERNALLY STRAINED SI(100) OBSERVED WITH SCANNING TUNNELING MICROSCOPY

Applying a uniaxial strain to Si(100) lifts the orientational degeneracy of the surface energy for 2X 1 and 1X2 domains, with a corresponding population increase for the favored domains. An external uniaxial strain was applied to Si(100) by pushing or pulling the free end of a long thin cantilevered sample and the resulting domain structure was observed with a scanning tunneling microscope (STM). On externally unstrained Si(100) there were equal populations of 2X1 and 1X2 domains. The STM images show that under strain individual domains of 2 × 1 grew in size at the expense of individual domains of 1X 2, and the pattern on the strained surface was a large majority terrace, a single-atom-high step to a thin minority terrace, followed by a single-atom-high step back to a large majority terrace. The minority domains formed thin terraces which could have meandering directions. Regions of 2X2 reconstruction were frequently observed on the strained surface. © 1990, American Vacuum Society. All rights reserved.