Atomic scale control and understanding of cubic silicon carbide surface reconstructions, nanostructures and nanochemistry

Abstract

The atomic scale ordering and properties of cubic silicon carbide (β-SiC) surfaces and nanostructures are investigated by atom-resolved room and high-temperature scanning tunnelling microscopy (STM) and spectroscopy (STS), synchrotron radiation-based valence band and core level photoelectron spectroscopy (VB-PES, CL-PES) and grazing incidence x-ray diffraction (GIXRD). In this paper, we review the latest results on the atomic scale understanding of (i) the structure of β-SiC(100) surface reconstructions, (ii) temperature-induced metallic surface phase transition, (iii) one dimensional Si(C) self-organized nanostructures having unprecedented characteristics, and on (iv) nanochemistry at SiC surfaces with hydrogen. The organization of these surface reconstructions as well as the 1D nanostructures' self-organization are primarily driven by surface stress. In this paper, we address such important issues as (i) the structure of the Si-rich 3 × 2, the Si-terminated c(4 × 2), the C-terminated c(2 × 2) reconstructions of the β-SiC(100) surface, (ii) the temperature-induced reversible c(4 × 2) ⇔ 2 × 1 metallic phase transition, (iii) the formation of highly stable (up to 900 • C) Si atomic and vacancy lines, (iv) the temperature-induced sp to sp 3 diamond like surface transformation, and (v) the first example of H-induced semiconductor surface metallization on the β-SiC(100) 3 × 2 surface. The results are discussed and compared to other experimental and theoretical investigations.

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

“…In the case of SiC(0001), the surface after annealing at 1,500 K consists of a combination of atomically flat terraces partially covered with single-layer graphene (Fig. 2a) and other areas with a carbonaceous termination consisting either of a mixture of Si and C atoms in sp 2 /sp 3 configuration or bilayer graphene (BLG) 23,27 . The graphene termination of different SiC specimens after being submitted to high temperature has been observed in different previous studies, both for large grains or small nanoparticles 22,23 .…”

“…2a) and other areas with a carbonaceous termination consisting either of a mixture of Si and C atoms in sp 2 /sp 3 configuration or bilayer graphene (BLG) 23,27 . The graphene termination of different SiC specimens after being submitted to high temperature has been observed in different previous studies, both for large grains or small nanoparticles 22,23 . Therefore, we conclude that the SiC grains present at CSE end with a graphene cover, as the one shown in Fig.…”

“…This theory-experiment combination provides a state-of-the-art morphological, structural and spectroscopic description about molecular interactions on SiC crystallites under CSE conditions. In addition, SiC has also been widely studied in condensed matter research and nowadays it is well accepted that all SiC crystalline structures are covered with graphene after annealing in vacuum 22,23 .…”

Metallization of the β-SiC(100) 3×2 surface: A DFT investigation

“…Hence, it is noteworthy to mention the 1 st example of H inducing metallization of a semiconductor surface has been shown for a β-SiC(100)3x2 reconstruction [7,8] along with an isotopic effect occurring when using deuterium [9]. Additionally, surface metallization induced by hydrogen adsorption has also been reported for ZnO and Ge [10,11].…”

“…The H/D atoms interaction with this reconstructed β-SiC(100) 3x2 surface has been investigated by different state-of-the-art experimental techniques including STM, scanning tunneling spectroscopy (STS) [7,8], valence band photoemission (VB-PES) [6][7][8][9], infrared absorption (IRAS) [7,16] and core level photoemission spectroscopies (CL-PES) [17]. These experimental investigations provided a model where H/D atoms are: i) decorating the top-most surface Si atoms' dangling bonds; ii) causing an asymmetric attack into the 3 rd Si atomic plane (just above the 1 st C plane).…”