Unraveling the obscure electronic transition and tuning of Fermi level in Cu substituted Bi2Te3 compound

Observation of a broad peak in the temperature (T) dependent resistivity (ρ) in Cu substituted Bi2Te3 has been reported earlier, though its origin remains obscured to date. Our investigation reveals that an electronic phase transition accompanied by Fermi level tuning primarily contributes toward the observed ρ(T). The analysis reveals that tuning of the Fermi level affects bulk transport phenomena to produce the unique ρ(T). We have proposed a model to show how the bulk bandgap can affect ρ(T). We have shown that bulk carrier contribution has a greater role in producing such ρ(T), and a detailed discussion supported by temperature dependent ARPES study, Raman study, and XPS study as well as structural study conducted by x-ray diffraction has been presented.