Asymmetric Doping in Silicon Nanostructures: The Impact of Surface Dangling Bonds

• Published in: Nano letters Vol. 10; no. 5; pp. 1671 - 1676
• Main Authors: Hong, Ki-Ha, Kim, Jongseob, Lee, Jung Hoon, Shin, Jaikwang, Chung, U-In
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12.05.2010
• Subjects: Binding Sites; Computer Simulation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron states; Exact sciences and technology; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Macromolecular Substances - chemistry; Materials science; Methods of electronic structure calculations; Models, Chemical; Models, Molecular; Molecular Conformation; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanostructures - chemistry; Nanostructures - ultrastructure; Particle Size; Physics; Quantum wires; Silicon - chemistry; Surface Properties; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); dopant deactivation; silicon nanocrystal; Silicon nanostructure; asymmetric doping; doping; silicon nanowire; trap; surface dangling bond; Quantum confinement; Dangling bonds; Conduction bands; p type semiconductor; Doping; Growth mechanism; Density functional method; Quantum effect; Silicon; Nanowires; Nanostructures; Nanostructured materials
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl904282v

We investigate peculiar dopant deactivation behaviors of Si nanostrucures with first principle calculations and reveal that surface dangling bonds (SDBs) on Si nanostructures could be fundamental obstacles in nanoscale doping. In contrast to bulk Si, as the size of Si becomes smaller, SDBs on Si nanostructures prefer to be charged and asymmetrically deactivate n- and p-type doping. The asymmetric dopant deactivation in Si nanostructures is ascribed to the preference for negatively charged SDBs as a result of a larger quantum confinement effect on the conduction band. On the basis of our results, we show that the control of the growth direction of silicon nanowire as well as surface passivation is very important in preventing dopant deactivation.