STM Observation of the Si(111) - (7×7) Reconstructed Surface Modified by Excess Phosphorus Doping

Abstract

<span>The electronic properties of semiconductor surfaces change readily upon changing the carrier densities by controlling the dopant concentration. Additionally, excess dopant atoms can exert electric field which would affect the molecular adsorption process and could be used to manipulate the dynamic movement of confined molecules. A mechanism can be developed to control the molecular dynamic movement on modified semiconductor surface by dopants thus changing the effect of the electric field on the active molecules. In this study, the Si(111) surface was doped with phosphorus excessively using thermal diffusion process. The surface was then reconstructed to the 7 × 7 configuration via heating under UHV conditions and then studied through STM and STS techniques. The protrusions due to surface and subsurface P atoms appear brighter due to the lone electron pair. The 7 × 7 reconstruction would be destabilized after a critical P substitution of Si-adatom concentration due to high surface strain result in P-terminated (6√3 × 6√3)</span><em><span>R</span></em><span>30º reconstruction.</span>

Van der Waals and Graphene-Like Layers of Silicon Nitride and Aluminum Nitride

“…Similar peaks were observed by many groups [21,24,[32][33][34][35][36][37], and they are usually denoted as S 1 = −0.3 eV, S 2 = −0.8 eV, and S 3 = −1.4 eV; we also observed a state at −2.3 eV, which was detected by the XPS method [38]. Some authors associate certain peaks in the density of state spectrum with specific atoms on the surface (7 × 7), for example, peaks at −0.3 and + 0.3 V are associated with adatoms [21,32], and the peak at −0.8 V is associated with rest atoms [32,37], that is, they are considered in the framework of the approximation of the local density of electronic states of a given atom. However, our experimental data, namely the presence of identical peaks for the entire family of spectra, for both adatoms and rest atoms and other characteristic points, show that these peaks on the surface of pure silicon should be considered as a manifestation of the surface two-dimensional bands of states of the structure (7 × 7).…”