Parallel adatom chains on Si(111): A chemisorption-induced surface reconstruction.

Abstract

(ML), to as high as -3 ML [11,12]. We find that the CaFz/Si(111)-(3 X 1) reconstruction is primarily a Si reconstruction, with a parallel array of zigzag Si adatom chains oriented along (110). The basic structural unit, the adatom chain, forms a five-member ring in (110) projection. The domain size of the (3 X 1) phase is comparable to that of the original Si(111)-(7 X 7) reconstruction on our samples. Moreover, this surface structure, with no dangling bonds at only 3 monolayer adsorbate coverage, may explain the occurrence of (3 X 1) reconstructions among a diverse range of Si-adsorbate systems. The experiment was performed at beam line X-16A of the National Synchrotron Light Source (NSLS), with an ultrahigh vacuum (UHV) system coupled to a five-circle diffractometer [13]. Dipole magnet radiation was focused to a beam size of -1.0 mm X 1.5 mm at the sample, and monochromatized to a wavelength of 1.37 k For the inplane measurements, the incident angle of the x-ray beam to the sample surface was equal to the exit angle, P = 0.7, which is well above the Si critical angle. Scattered x rays were collected using a position-sensitive detector held at a constant angle relative to the sample surface, and binned to give an angular resolution of -0.35 along the