Abh�ngigkeit der effektiven Masse von der Ladungstr�gerkonzentration im Bi2Se3

Abstract

High quality BizSe 3 crystals with 50 to 65 At % Se have been produced. As a consequence of a Se-doping, the carrier density varies between 3 9 1019 to 8 9 1017 cm -3. Based on optical reflection and transmission measurements in the near infrared the dispersion of the refractive index n(2) has been calculated. The plasma resonance frequency Vp1 lies within the energy region from 0.05 to about 0.1 eV. From n(2) and Vpl the effective mass of the electrons in Bi2Se 3 has been evaluated. Near the band edge a value of m~_e=0.02 m 0 has been found. It depends on the orientation of the crystals and on the carrier concentration. The results of the electrical and optical investigations give reason to assume an isotropic mean free time of the electrons. The "six-valley-model" of HASHIMOTO for the energy-surfaces in BizSe3, is confirmed.

Proximity-effect-induced Superconducting Gap in Topological Surface States – A Point Contact Spectroscopy Study of NbSe2/Bi2Se3 Superconductor-Topological Insulator Heterostructures

“…Based on the resistivity anisotropy measurements of single crystals and selected orientation thin films made by MBE 32, 33 , we take the resistivity anisotropic ratio to be ~ 4. Using a c-direction effective mass from the results of reflectance studies of Bi 2 Se 3 crystals 34 and  =  from the band structure calculations 20 , the out-of-plane mean free path is estimated to be ~16 nm for the bulk Bi 2 Se 3 . This is very close to the Bi 2 Se 3 thickness threshold when no NbSe 2 gap is observed.…”

Conduction Band Parameters of Bi2See from Shubnikov‐de Haas Investigations

“…Free carrier infrared dispersion and Hall effect data yielded a strongly concentration-dependent susceptibility mass perpendicular to the c-axis [4]. First results from Shubnikovde Haas (SdH) experiments were reported earlier [B].…”

Potential Thermoelectric Performance from Optimization of Hole-DopedBi2Se3

“…Bi 2 Se 3 ordinarily forms n-type specimens, so that more literature on n-type is available. Typical n-type mobilities at or even somewhat above these concentrations [35][36][37][38][39][40][41] are in this range or higher, so that assuming no great asymmetry in n-type vs p-type scattering rates, the assumed p-type mobilities are reasonable. The assumed carrier concentration dependence implies that mobility increases significantly as carrier concentration decreases, which is generally true until one reaches a limiting value, as in Ref.…”