Studies of the Dielectric Constant of Thin Film Bismuth Nanowire Samples Using Optical Reflectometry
Abstract
Arrays of 10 to 120 nm diameter single crystalline bismuth nanowires have been formed inside amorphous alumina templates. Since bismuth has a small effective mass compared to other materials, significant quantum mechanical confinement is expected to occur in wires with diameter less than 5O microns. The subbands formed by quantum confinement cause interesting modifications to the dielectric function of bismuth, This study measures the dielectric function of bismuth nanowires in an energy range where the effects of quantum confinement are predicted (0.05 to 0.5 eV). Using Fourier transform infrared reflectometry, the dielectric constant as a function of energy is obtained for the alumina/bismuth composite system. Effective medium theory is used to subtract the effect of the alumina template from the measurement of the composite material, thus yielding the dielectric function of bismuth nanowires. A strong absorption peak is observed at approx. 1000/cm in the frequency dependent dielectric function in the photon energy range measured. The dependence of the frequency and intensity of this oscillator on incident light polarization and wire diameter are reviewed. In addition the dependence of the optical absorption on antimony and tellurium doping of the nanowires are reported.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2001
- Accession Number
- ADP011026
Entities
People
- M. Padi
- M. R. Black
- O. Rabin
- S. B. Cronin
- Y. -m Lin
Organizations
- Massachusetts Institute of Technology