Temperature dependence of the Raman spectrum of orthorhombic Bi2Se3
arxiv(2024)
摘要
Bismuth selenide, a benchmark topological insulator, grows in a trigonal
structure at ambient conditions and exhibits a number of enticing properties
related to the formation of Dirac surface states. Besides this polytype, a
metastable orthorhombic modification with Pnma space group has been produced by
electrodeposition and high-pressure high-temperature synthesis displaying upon
Sb doping significant thermoelectric properties in the midtemperature range.
However, very little experimental information is available on the fundamental
properties of this polytype, such as, e.g., the electronic band gap and the
lattice dynamics. We report here the temperature dependence of the Raman
spectra of orthorhombic Bi2Se3 between 10 K and 300 K, which displays an
anharmonic behavior of the optical phonons that can be modelled with a
two-phonon decay channel. In order to analyze the data we performed ab initio
calculations of the electronic bandstructure, the phonon frequencies at the
center of the Brillouin zone, and the phonon dispersion relations along the
main symmetry directions, examining the effect of spin-orbit coupling in both
phonon and electronic energies. Lastly, we report here cathodoluminescence
experiments at 83 K that set a lower limit to the electronic bandgap at 0.835
eV, pointing to an indirect nature, in agreement with our calculations. These
results shed light to essential properties of orthorhombic Bi2Se3 for further
understanding of the potential of this semiconductor for thermoelectrics and
new applications.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要