We report electrical (angular magneto-resistance, and Hall), thermal (heat capacity) and spectroscopic (Raman, x-ray photo electron, angle resolved photo electron) characterization of bulk Bi 2 Se 3 topological insulator, which is being is grown by self flux method through solid state reaction from high temperature (950˚C) melt and slow cooling (2˚C/hour) of constituent elements. Bi 2 Se 3 exhibited metallic behaviour down to 5K. Magneto transport measurements revealed linear up to 400% and 30% MR at 5K under 14 Tesla field in perpendicular and parallel field direction respectively. We noticed that the magneto-resistance (MR) of Bi 2 Se 3 is very sensitive to the angle of applied field. MR is maximum when the field is normal to the sample surface, while it is minimum when the field is parallel. Hall coefficient (R H ) is seen nearly invariant with negative carrier sign down to 5K albeit having near periodic oscillations above 100K. Heat capacity (C p ) versus temperature plot is seen without any phase transitions down to 5K and is well fitted (Cp = γT + βT 3 ) at low temperature with calculated Debye temperature (Ѳ D ) value of 105.5K. Clear Raman peaks are seen at 72, 131 and 177 cm -1 corresponding to A 1g 1 , E g 2 and A 1g 2 respectively. Though, two distinct asymmetric characteristic peak shapes are seen for Bi 4f 7/2 and Bi 4f 5/2 , the Se 3d region is found to be broad displaying the overlapping of spin -orbit components of the same. Angle-resolved photoemission spectroscopy (ARPES) data of Bi 2 Se 3 revealed distinctly the bulk conduction bands (BCB), surface state (SS), Dirac point (DP) and bulk valence bands (BVB) and 3D bulk conduction signatures are clearly seen. Summarily, host of physical properties for as grown Bi 2 Se 3 crystal are reported here.

In this letter, we report growth and characterization of bulk Bi 2 Se 3 single crystals. The

We report the exotic photoluminescence (PL) behaviour of 3D topological insulator Bi2Te3 single crystals grown by customized self-flux method and mechanically exfoliated few layers (18 ± 2 nm)/thin flakes obtained by standard scotch tape method from as grown Bi2Te3 crystals. The experimental PL studies on bulk single crystal and mechanically exfoliated few layers of Bi2Te3 evidenced a broad red emission in the visible region from 600–690 nm upon 375 nm excitation wavelength corresponding to optical band gap of 2 eV. These findings are in good agreement with our theoretical results obtained using the ab initio density functional theory framework. Interestingly, the observed optical band gap is several times larger than the known electronic band gap of ~0.15 eV. The experimentally observed 2 eV optical band gap in the visible region for bulk as well as for mechanically exfoliated few layers Bi2Te3 single crystals clearly rules out the quantum confinement effects in the investigated samples which are well known in the 2D systems like MoS2,WS2, WSe2, and MoSe2 for 1–3 layers.