Electron delocalization and relaxation behavior in Cu-doped Bi2Se3 films

Abstract

Cu x Bi 2 Se 3 is known for superconductivity due to Cu intercalation in the van der Waals gaps between the quintuple layers of Bi 2 Se 3 at x > 0.10. Here we report the synthesis and transport properties of Cu-doped Cu x Bi 2 Se 3 films prepared by chemical-vapor-deposition (CVD) method with 0.11 ≥ x ≥ 0. It is found that the insulating-like temperature-dependent resistivity of polycrystalline Cu x Bi 2 Se 3 films exhibits a marked metallic downturn and an increase of carrier concentration below ~37K. There is also a time-dependent slow relaxation behavior in the resistance at low temperature. These effects might be related to the strong hybridization between Cu + and Cu 2+ conduction bands from the intercalated Cu + and substituted Cu 2+ sites in Bi 2 Se 3 films. The findings here have important implications for the understanding and development of doping induced superconductivity in topological insulators.

Structural and Magnetotransport Studies of Iron‐Intercalated Bi2Se3 Single Crystals

“…The redshift implies that Fe atoms occupy the sites between QLs and weakens the interaction between layers, which results in the decrease in phonon mode energy. The high quality of the crystal can be observed clearly, as the low‐frequency E g 1 mode has been observed in this work, which is absent in most of the reports . Table shows the shift in peak positions for the different observed modes.…”

The dimensional crossover of quantum transport properties in few-layered Bi2Se3 thin films

“…[33][34][35] To obtain a greater transport contribution from the topological SS, it is important to obtain TI thin lms with a high crystallization quality. The methods usually used for preparing TI thin lms include molecular beam epitaxy (MBE), 33,[36][37][38][39][40] chemical vapor deposition, [41][42][43][44] physical vapor deposition, [45][46][47][48] pulsed laser deposition (PLD) [49][50][51][52][53][54][55][56][57][58][59][60] and sputtering. 61,62 The MBE is the method mainly used to obtain at and thin TI lms for fundamental research, because of its advantages of 2D growth, single crystal yield and easily controlled doping.…”

Boosting the surface conduction in a topological insulator

“…The lack of consensus of the microscopic mechanism impedes progress. Slow relaxation behaviours have also been observed in experiments without irradiation 10,11 . The salient feature of all these studies 4-11 -persistence with non-exponential relaxation-suggests a common underlying origin.…”

“…The mechanism proposed here-space-charge separation between the surface and bulk carriers-is relevant for any topological insulator. It is surprising that these effects have remained largely unnoticed and not understood [4][5][6][7][8][9][10][11] . Possibly, the anomaly in transport observed in Cd-doped Bi 2 Se 3 42 and Sn-doped Bi 1.1 Sb 0.9 Te 2 S 43 are…”