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ZJU Makes Remarkable Advances in Research into Two-Dimensional Electron Gas

[From]:浙江大学[Editor]:[Date]:2015/07/08[Hits]:7

The two-dimensional electron gas (2DEG) at the interface of the heterostructures of semiconductors opens up exciting possibilities for novel physical phenomena and new electronic devices. Researchers from the Department of Physics of Zhejiang University, the Sandia National Laboratories of the USA, the Department of Electrical Engineering of the University of North Carolina at Charlotte and the Los Alamos National Lab of the USA conducted joint research into 2DEG at the rocksalt/zincblende interface of PbTe/CdTe (111) heterostructures.

Quantum oscillations are observed in the 2DEG system at the interface of novel heterostructures, PbTe/CdTe (111), with nearly identical lattice parameters (aPbTe = 0.6462 nm, aCdTe = 0.648 nm) but very different lattice structures (PbTe: rock salt, CdTe: zinc blende). The 2DEG formation mechanism, a mismatch in the bonding configurations of the valence electrons at the interface, is uniquely different from the other known 2DEG systems. The aberration-corrected scanning transmission electron microscope (AC-STEM) characterization indicates an abrupt interface without cation interdiffusion due to a large miscibility gap between the two constituent materials. Electronic transport measurements under magnetic field up to 60 T, with the observation of Landau level filling factor ν=1, unambiguously reveal a π Berry phase, suggesting the Dirac Fermion nature of the 2DEG at the heterostructure interface, and the PbTe/CdTe heterostructure being a new candidate for 2D topological crystalline insulators.
(a) Aberration-corrected scanning transmission electron microscope (AC-STEM) image of a PbTe/CdTe heterojunction, showing the arrangement of atoms near the interface.
(b) Quantum oscillations of magneto-resistance Rxx and Hall resistance Rxy.
(c) Quantum oscillations of magneto-resistance Rxx with magnetic field up to 60 T.
(d) Landau level fan diagram. The intercept at 1/B = 0 is −0.52 ± 0.07.