Transport Properties of Bi-related Nanowire Systems
- PDF / 316,074 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 20 Downloads / 183 Views
Transport Properties of Bi-related Nanowire Systems Y. M. Lin,1 S. B. Cronin,2 J. Y. Ying,3 J. Heremans,4 and M. S. Dresselhaus1,2,* Department of Electrical Engineering and Computer Science, 2Department of Physics, 3 Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 4 Delphi Research Labs, Delphi Automotive Systems, Warren, MI 48090 * On leave from the Massachusetts Institute of Technology, Cambridge, MA 02139 1
ABSTRACT We present here an electrical transport property study of Te-doped Bi nanowires, and Bi1-xSbx alloy nanowires embedded in a dielectric matrix. The crystal structure of the nanowires were characterized by X-ray diffraction measurements, indicating that the nanowires possess the same lattice structure as bulk Bi in the presence of a small amount of Te or Sb atoms. The resistance measurements of 40-nm Te-doped Bi nanowires were performed over a wide range of temperature (2 K≤ T ≤ 300 K), and the results are consistent with theoretical predictions. The 1D-to-3D localization transition and the boundary scattering effect are both observed in magneto-resistance measurements of Bi1-xSbx alloy nanowires at low temperatures (T < 4 K). INTRODUCTION Nanostructured materials have received much attention in the last decade because of their importance in fundamental studies and potential applications in diverse fields, such as chemistry, biology, optics, microelectronics, materials science, and thermoelectrics [1]. Various unusual phenomena and properties have been predicted and observed in nanoscaled materials. Among existing nanostructures, nanowires represent one of the most interesting systems because they exhibit stronger quantum confinement effects than 2D nanostructures such as superlattices, and they maintain structural continuity in one dimension, which allows for transport phenomena and they may serve as interconnections in future microelectronics applications. Bismuth (Bi) is a very attractive material for the study of low-dimensional systems. Bi is a group V semimetal, in which the electrons are distributed in three highly anisotropic carrier pockets at the L points of the Brillouin zone, and the holes are contained in one pocket at the T point. The small energy overlap (38 meV at 77 K) in bulk Bi between the L-point conduction band and the T-point valence band is predicted to vanish in Bi nanowires when the diameter is smaller than ~50 nm, thus causing a semimetal-to-semiconductor transition [2]. Experimental results for this quantum-confinement-induced semimetal-semiconductor transition in Bi nanowires have been previously reported [3-4]. Since Bi has very small electron effective masses (~0.001 m0 along the binary direction), quantum confinement effects can be observed at a larger scale (~50 nm), compared to less than 10 nm for most metals or semiconductors. In addition to band shifts due to quantum confinement effects, it is also possible to controllably alter the energy-band structure and transport properties of Bi by alloying with another Group V ele
Data Loading...
