Dynamical Conductivity and Plasmon Excitation in Bi

Abstract

The reflectivity of bismuth crystals is measured in the spectral range 50 to 600 cm-l. From the measured data the dielectric function is determined by a'Kramers-Kronig analysis. The dispersion of this function is explained by the dynamical conductivity of a free electron gas. At frequencies above the plasma edge there is a contribution which is due to the excitation of plasmons by the interaction of the free electrons with the Coulomb fields of impurities. This contribution can be expected from model calculations of the dynamical conductivity, considering ionized impurity scattering and screening effects.An Wismut-Kristallen wird das Reflexionsvermogen im Spektralbereich zwischen 50 und 500 cm-I gemessen. Aus den Messungen wird die dielektrische Funktion durch eine Kramers-Kronig-Analyse ermittelt, ihr spektraler Verlauf wird durch die dynamische Leitfiihigkeit des freien Elektronengases erkliirt. Ein Beitrag bei Frequenzen oberhalb der Plasmakante wird Plasmonen zugeschrieben, die durch die Wechselwirkung der freien Elektronen mit den Coulomb-Feldern ionisierter Storstellen angeregt werden. Ein solcher Beitrag wird aus Modellrechnungen fur die dynamische Leitfiihigkeit erwartet, wenn man die Streuung an ionisierten Storstellen und Abschirmeffekte betrachtet.

Intersubband Transitions in Thin Bismuth Films

“…The relation yields with mxx = 0.00641m0 and myy = 1.362m0 [16] m* = 0.0128m,. Inserting the electron concentration at 5 K, n = 3.2 x 10" cm-3 [17], we obtain ~u,,/27cc = 1496 cm-', in fact in considerable agreement with the measured value, wp/2nc = 1590cm-I [14]. Due to the thickness dependent subbands, the plasma frequencies of thin samples cannot be interpreted using (13) with the bulk values for m* at the Fermi level, and (11) has to be evaluated taking into account size quantization.…”

“…The relation of the current to an electric field Ex normal to the trigonal c-axis of the films in the semiclassical model of nearly free conducting electrons [14] is…”

Optical studies of metallodielectric photonic crystals: Bismuth and gallium infiltrated opals

“…24 Our measurements reveal some of them: there is a prominent shoulder at Ϸ4 eV, a broad peak at about 1.4 eV ͑denoted here VC ), and small peaks at Ϸ0.7 and Ϸ0.4 eV. Due to the small concentration of free carriers (Ϸ10 18 cm Ϫ3 ) the corresponding plasma frequency in bismuth was found to be in the far-IR range, 25,26 and thus is not shown in Fig. 2͑a͒.…”

A Contribution to DC Transport in Thin Bi Films

“…or due to extrinsic impurities etc. It is possible to take these perturbations into account similarly as the ionized impurities in (15). I n the present paper, however, we will take a more global view and describe these perturbations (in addition to ionized impurities and carrier fluctuations) by a scattering frequency w,.…”