Doping and Electrical Transport in Silicon Nanowires

Single-crystal n-type and p-type silicon nanowires (SiNWs) have been prepared and characterized by electrical transport measurements. Laser catalytic growth was used to introduce controllably either boron or phosphorus dopants during the vapor phase growth of SiNWs. Two-terminal, gate-dependent measurements made on individual boron-doped and phosphorus-doped SiNWs show that these materials behave as p-type and n-type materials, respectively. Estimates of the carrier mobility made from gate-dependent transport measurements are consistent with diffusive transport. In addition, these studies show it is possible to heavily dope SiNWs and approach a metallic regime. Temperature-dependent measurements made on heavily doped SiNWs show no evidence for Coulomb blockade at temperatures down to 4.2 K, and thus testify to the structural and electronic uniformity of the SiNWs. Potential applications of the doped SiNWs are discussed.