Films*

BiSbTe alloys are a part of an intriguing class of quantum materials known as topological insulators (TIs). We present our investigation of the local band structure of topologically insulating (Bi_1-xSb_x)₂Te₃ thin films using scanning tunneling microscopy/spectroscopy (STM/S) and magneto-transport (MT) measurements. Both STS and Hall transport measurements reveal a tunable electronic structure, with a n-type to p-type crossover for (Bi_1-xSb_x)₂Te₃ thin films at x ≈ 0.6. However, Hall measurements show n-type conduction while STS shows p-type conduction for films of varying thicknesses. This n/p anomaly is due to the distinct transport behaviors of the bulk and surface states. We directly probe both bulk and surface states in these films using STS. Both the Fermi level and the Dirac point are located inside the bulk band gap, indicating bulk-like insulating behavior with accessible surface states. We further discuss bulk and surface contributions to conduction. Prior to this work, direct detection of topological surface states in BiSbTe systems has been achieved only for T<10 K. This work demonstrates the first direct measurement of topological surface states using STS at room temperature for any material.