Influence of Chemical Composition of Liquid Phase and Growth Process on Physical Properties of Bi₂Se₃, Bi₂Te₃and Bi₂Te₂Se Compounds

Abstract

We studied synthesis and crystal growth of Bi2Te3, Bi2Se3 and Bi2Te2Se compounds by means of vertical Bridgman method. Crystals were grown from stoichiometric melts and under different molar ratio of Bi:Te, Bi:Se or Bi:Te:Se. The obtained crystals were characterized by X-ray diffraction analysis, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, and the Hall effect measurements. Some of the samples demonstrated insulating bulk behavior, by means of resistivity versus temperature measurements.

Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi2Se3

“…Hall measurements58 yield a bulk hole density of 1.34 × 10 17  cm −3 and a mobility of 275 cm 2  V −1  s −1 . Using these values, the effective mass inferred from ARPES data and the Drude formula, we extract a velocity relaxation time of 18 fs in the bulk material.…”

Defects and high bulk resistivities in the Bi-rich tetradymite topological insulator Bi2+xTe2−xSe

“…We therefore grew a series of Bi 2+x Te 2−x Se crystals, with a maximum x of 0.06, by the classic Bridgeman-Stockbarger method. 25,34 The boules obtained in these growths are approximately 14 cm in length and 0.6 cm in diameter. Due to the chemical composition distribution that naturally occurs along crystal boules during such growth, the electrical properties at different positions in the boules are expected to be different.…”

Phase Separation and Bulk p‐n Transition in Single Crystals of Bi2Te2Se Topological Insulator

“…Some studies have suggested the presence of a unique Bi 2 Te 2 Se phase,9, 11 and, by thermal quenching from high temperature, it is possible to produce single‐phase Bi 2 Te 2 Se crystals with the disordered structure preserved 9. Other studies indicate that the Bi 2 Te 2 Se “phase” may in reality be a mixture of phases, as indicated by the broadening of powder X‐ray diffraction (PXRD) peaks of Bi 2 Te 2 Se, compared with those of Bi 2 Te 3 12. Due to the importance of Bi 2 Te 2 Se in both the thermoelectric and TI fields, we have undertaken a thorough characterization of the Bi 2 Te 2 Se single crystals grown by the Stockbarger method, to obtain a clear understanding of the composition, structure, defects, and properties.…”