Long‐Range Interaction Between NO2 Molecules, Impurity Boron Atoms and Si Atoms with Dangling Bonds in Porous Silicon

Abstract

Density functional theory (DFT) simulation show that in p‐doped porous silicon (PS), boron (B) atoms are passivated by surface dangling bonds of Si atoms (pb‐centers) at distances up to 25 Å. A positive charge of the pb‐centers leads to the appearance of an increased potential region and a Coulomb blockade (CB) of free holes. When a NO2 molecule is adsorbed on a surface OH group near the pb‐center, a shallow acceptor state arises. This state is related to the NO2 molecule and not to the B atom. When an electron is captured from the valence band by the NO2 molecule, the potential around it and the pb‐center decreases, which removes CB.