Publication Date:
2015-06-24
Description:
The requirement for large bulk resistivity in topological insulators has led to the design of complex ternary and quaternary phases with balanced donor and acceptor levels. A common feature of the optimized phases is that they lie close to the p - to n -transition. The tetradymite Bi 2 Te 3− x Se x system exhibits minimum bulk conductance at the ordered composition Bi 2 Te 2 Se. By combining local and integral measurements of the density of states, we find that the point of minimum electrical conductivity at x = 1.0 where carriers change from hole-like to electron-like is characterized by conductivity of the mixed type. Our experimental findings, which are interpreted within the framework of a two-band model for the different carrier types, indicate that the mixed state originates from different types of native defects that strongly compensate at the crossover point.
Electronic ISSN:
2166-532X
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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