Nano Electronics on Atomically Controlled van der Waals Quantum Heterostructures
Technical Report,15 Aug 2015,14 Feb 2017
HARVARD COLLEGE PRESIDENT and FELLOWS OF Cambridge United States
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We report molecular beam epitaxial growth and electronic transport properties of high quality topological insulator Bi2Se3 thin films on hexagonal boron nitride. We present a comprehensive study on topological insulator TI Bi2Se3 thin films on hexagonal boron nitride h-BNcareful heteroepitaxial growth using molecular beam epitaxy MBE and thorough characterizations of their structural and electrical properties. TIs have been spotlighted for their exotic charge and spin transport properties through topologically protected Dirac surface states.Bi2Se3 has in particular attracted an intense attention due to its well-separated topological surface states TSSs located in the bulk band gap energy, the largest among the group V2-VI3 TI family. However, experimental efforts on Bi2Se3 have been frequently resulted in the bulk conduction being dominant over TSSs in transport due to bulk doping effects of defect sites. The usual approach to avoid this problem is compensation-doping or alloying. While this approach has been successful in probing the various novel phenomena exhibited by TSSs, it unavoidably results in energy gap smaller than that of pristine Bi2Se3 or an increased degree of disorder, potentially degrading its merits in device applications. On the other hand, high quality TI Bi2Se3 with a reduced concentration of defects can be achieved by the heteroepitaxial growth on a substrate with a compatible lattice structure. h-BN is one of the ideal substrates for Bi2Se3 in this purpose since they share the hexagonal lattice symmetry and dangling-bond-free two-dimensional 2D van der Waals vdW layered structure.
- Electrical and Electronic Equipment