Comment on "Quantum transport in the surface states of epitaxial Bi(111) thin films"

Zhu et al. [Phys. Rev. B 94, 121401(R) (2016)] recently reported an experimental work that claims that epitaxial Bi(111) films grown on Si(111) are (1) topologically nontrivial, and (2) metallic only at the surface and insulating in the interior bulk, consistent with the old prediction of a semimetal-to-semiconductor (SMSC) transition. Here we point out that although Bi can be nontrivial, the SMSC transition does not happen at the same time. Through the comparison of the thickness and temperature dependence of the film conductivity of Bi with Bi0.9Sb0.1 performed in situ, we find no evidence of the insulating bulk states of Bi when the thickness is less than 240 angstrom, which is in accordance with our angle-resolved photoemission spectroscopy measurements and density functional theory calculations.