Electron microscopy of the ordered boron 2 × 1 structure buried in crystalline silicon

• Published in: Applied surface science Vol. 84; no. 4; pp. 413 - 418
• Main Authors: Weir, B.E., Eaglesham, D.J., Feldman, L.C., Luftman, H.S., Headrick, R.L.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1995; Elsevier Science
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Doping and impurity implantation in germanium and silicon; Exact sciences and technology; Physics; Solid surfaces and solid-solid interfaces; Structure of solids and liquids; crystallography; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Surface reconstruction; Semiconductor materials; Boron additions; Planar doping; Doping profiles; SIMS; Silicon; Experimental study; TEM; Surface structure
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/0169-4332(95)00015-1

The fabrication of an ordered dopant distribution within a semiconductor provides an exciting challenge to thin-film growth. In this paper the structure of an ordered boron layer embedded in silicon is analyzed by electron microscopy. Planar-transmission electron diffraction confirms preservation of the 2 × 1 ordered boron layer beneath the crystalline Si cap. High-resolution transmission electron microscopy in cross-section clearly identifies the BSi layer and shows that the width of this layer in the growth direction is ≤ 5 monolayers (ML). This confirms earlier X-ray diffraction and Auger electron spectroscopy results which determined the boron spreading to be ∼ 3 ML. Secondary ion mass spectroscopy results, showing a resolution-limited impurity profile, are also included. Plan-view imaging is used to identify defects in the structure. These results provide further insight into this unique dopant structure which yields the narrowest electrically active dopant profile reported.