Phys. Rev. B 92, 085417 (2015)
Freestanding Bi₂Se₃ single-crystal flakes of variable thicknesses are grown using a catalyst-free vapor-solid synthesis and are subsequently transferred onto a clean Si⁺⁺/SiO₂ substrate where the flakes are contacted in Hall bar geometry. Low-temperature magnetoresistance measurements are presented which show a linear magnetoresistance for high magnetic fields and weak antilocalization (WAL) at low fields. Despite an overall strong charge-carrier tunability for thinner devices, we find that electron transport is dominated by bulk contributions for all devices. Phase-coherence lengths l_ϕ as extracted from WAL measurements increase linearly with increasing electron density exceeding 1μm at 1.7 K. Although l_ϕ is in qualitative agreement with electron-electron interaction-induced dephasing, we find that spin-flip scattering processes limit l_ϕ at low temperatures.