Initial and secondary oxidation products on the Si(111)-(7 × 7) surface identified by atomic force microscopy and first principles calculations

• Published in: Applied physics letters Vol. 104; no. 13
• Main Authors: Onoda, Jo, Ondráček, Martin, Yurtsever, Ayhan, Jelínek, Pavel, Sugimoto, Yoshiaki
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 31.03.2014
• Subjects: Adatoms; Applied physics; ATOMIC FORCE MICROSCOPY; ATOMS; Bright spots; Chemical bonds; DENSITY FUNCTIONAL METHOD; Density functional theory; First principles; MATERIALS SCIENCE; Mathematical analysis; Microscopes; Microscopy; OXIDATION; SCANNING TUNNELING MICROSCOPY; SEMICONDUCTOR MATERIALS; SURFACES; TEMPERATURE RANGE 0273-0400 K
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4870629

We investigate the initial and secondary oxidation products on the Si(111)-(7 × 7) surface at room-temperature using atomic force microscopy (AFM) and density functional theory calculations. At the initial oxidation stages, we find that there are two types of bright spots in AFM images. One of them is identified as a Si adatom with one O atom inserted into one of the backbonds, while the other is ascribed to a Si adatom with two inserted O atoms. We observe that the latter one turns into the secondary oxidation product by a further coming O2 molecule, which appears as a more protruded bright spot. The atomic configuration of this product is identified as Si adatom whose top and all three backbonds make bonds with O atoms. The appearances of initial and secondary oxidation products are imaged as bright and dark sites by scanning tunneling microscopy, respectively. It is revealed that AFM gives us the topographic information close to the real atomic corrugation of adsorbed structures on the semiconductor surfaces.