The Structure of Si(112):Ga-(N x 1) Reconstructions
VIRGINIA COMMONWEALTH UNIV RICHMOND DEPT OF PHYSICS
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We have studied the structure of Si112Ga-N1 reconstructions using atomic-resolution scanning tunneling microscopy and first-principles calculations. The nanofaceted clean Si112 surface becomes planar following the adsorption of Ga, which forms long chains on the surface interrupted by isolated quasi-periodic defects. The defects create a mixture of N1 structures N4-7 with 5 1 and 6 1 unit cells most common. We demonstrate that this structure consists of a chain of Ga atoms adsorbed at the 111-like step edge within the 112 unit cell, and that the defects are Ga vacancies where the exposed step edge Si atoms form a dimer bond. Calculations performed as a function of vacancy period confirm that the surface energy is minimized at N5-6, when compressive strain associated with the Si-Ga bonds is effectively minimized.
- Inorganic Chemistry
- Electrooptical and Optoelectronic Devices