First-principles study of doped Si and Ge nanowires

• Published in: Physica. E, Low-dimensional systems & nanostructures Vol. 40; no. 6; pp. 2169 - 2171
• Main Authors: Peelaers, H., Partoens, B., Peeters, F.M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2008; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Doping and impurity implantation in germanium and silicon; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Formation energies; Nanowires; Physics; Quantum wires; Segregation; Structure of solids and liquids; crystallography; 73.21.Hb; Nanowires; Segregation; Formation energies; 73.22.Dj; 78.67.Lt; 73.21.Hb; 73.22.Dj; 78.67.Lt; Doping; Nanowires; Formation energies; Segregation; Phosphorus additions; Dangling bonds; Density functional method; Impurity site; Boron additions; Germanium; Silicon; Impurity states; Impurity segregation
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2007.10.090

Using density functional theory we calculate the formation energies for B and P doped Si and Ge nanowires which are oriented in the [1 1 0] direction. First the preferential position for the dopants is calculated in fully passivated nanowires. It is found that the dopants prefer the edge or near edge positions. Further we show that a dangling bond has a large influence on these formation energies. When a dangling bond is present, P dopants will segregate to the edge of the wire, thereby trapping its additional electron and thus lowering the conductance. For B dopants this effect is smaller.