Bi_2Te_3 thin films and GeTe/B_2Te_3 superlattices of different thicknesses are prepared on the silicon dioxide substrates by magnetron sputtering technique and thermally annealed at 573 K for 30 min. Thermoelectric...Bi_2Te_3 thin films and GeTe/B_2Te_3 superlattices of different thicknesses are prepared on the silicon dioxide substrates by magnetron sputtering technique and thermally annealed at 573 K for 30 min. Thermoelectric（TE）measurements indicate that optimal thickness and thickness ratio improve the TE performance of Bi_2Te_3 thin films and GeTe/B_2Te_3 superlattices, respectively. High TE performances with figure-of-merit（ZT） values as high as 1.32 and 1.56 are achieved at 443 K for 30 nm and 50 nm Bi_2Te_3 thin films, respectively. These ZT values are higher than those of p-type Bi_2Te_3 alloys as reported. Relatively high ZT of the GeTe/B_2Te_3 superlattices at 300-380 K were 0.62-0.76. The achieved high ZT value may be attributed to the unique nano-and microstructures of the films,which increase phonon scattering and reduce thermal conductivity. The results indicate that Bi_2Te_3-based thin films can serve as high-performance materials for applications in TE devices.展开更多
Majorana fermions have been predicted to exist at the edge states of a two-dimensional topological superconductor.We fabricated single quintuple layer(QL)Bi2Te3/FeTe heterostructure with the step-flow epitaxy method a...Majorana fermions have been predicted to exist at the edge states of a two-dimensional topological superconductor.We fabricated single quintuple layer(QL)Bi2Te3/FeTe heterostructure with the step-flow epitaxy method and studied the topological properties of this system by using angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy.We observed the coexistence of robust superconductivity and edge states on the single QL Bi2Te3 islands which can be potential evidence for topological superconductor.展开更多
Flower-like Bi2Te3 nanostructures were successfully synthesised for the first time by a simple magnetron technique or D.C. sputtering method. The phase and morphology of the products were characterized by X-ray diffra...Flower-like Bi2Te3 nanostructures were successfully synthesised for the first time by a simple magnetron technique or D.C. sputtering method. The phase and morphology of the products were characterized by X-ray diffraction （XRD）, manning electron microscope （SEM） and atomic force microscope （AFM）. It was found that the as-deposited Bi2Te3 has a well re-crystallized Rhombohedral phase and consisted of a wealth of flower-like structure, also the thermo-electric properties of Bi2Te3 were examined and we find that the Seebeck coefficient is 136.6μ volt/K.展开更多
Superlattice nanowires are expected to show further enhanced thermoelectric performance compared with conventional nanowires or superlattice thin films. We report the epitaxial growth of high density Bi2Te3/Sb superla...Superlattice nanowires are expected to show further enhanced thermoelectric performance compared with conventional nanowires or superlattice thin films. We report the epitaxial growth of high density Bi2Te3/Sb superlattice nanowire arrays with a very small bilayer thickness by pulse electrodeposition. Transmission electron microscopy, selected area electron diffraction and high resolution transmission electron microscopy were used to characterize the superlattice nanowires, and Harman technique was employed to measure the figure of merit （ZT） of the superlattice nanowire array in high vacuum condition. The superlattice nanowire arrays exhibit a ZT of 0.15 at 330 K, and a temperature difference of about 6.6 K can be realized across the nanowire arrays.展开更多
文摘Bi_2Te_3 thin films and GeTe/B_2Te_3 superlattices of different thicknesses are prepared on the silicon dioxide substrates by magnetron sputtering technique and thermally annealed at 573 K for 30 min. Thermoelectric（TE）measurements indicate that optimal thickness and thickness ratio improve the TE performance of Bi_2Te_3 thin films and GeTe/B_2Te_3 superlattices, respectively. High TE performances with figure-of-merit（ZT） values as high as 1.32 and 1.56 are achieved at 443 K for 30 nm and 50 nm Bi_2Te_3 thin films, respectively. These ZT values are higher than those of p-type Bi_2Te_3 alloys as reported. Relatively high ZT of the GeTe/B_2Te_3 superlattices at 300-380 K were 0.62-0.76. The achieved high ZT value may be attributed to the unique nano-and microstructures of the films,which increase phonon scattering and reduce thermal conductivity. The results indicate that Bi_2Te_3-based thin films can serve as high-performance materials for applications in TE devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61734008 and 11774143)the National Key Research and Development Program of China(Grant Nos.2018YFA0307100,2016YFA0301703,and 2016YFA0300300)+4 种基金the Natural Science Foundation of Guangdong Province,China(Grant Nos.2015A030313840 and 2017A030313033)the State Key Laboratory of Low-Dimensional Quantum Physics(Grant No.KF201602)Technology and Innovation Commission of Shenzhen Municipality,China(Grant Nos.ZDSYS20170303165926217 and JCYJ20170412152334605)Guangdong Provincial Key Laboratory,China(Grant No.2019B121203002)J.-W.M.was partially supported by the Program for Guangdong Introducing Innovative and Entrepreneurial Teams,China(Grant No.2017ZT07C062).
文摘Majorana fermions have been predicted to exist at the edge states of a two-dimensional topological superconductor.We fabricated single quintuple layer(QL)Bi2Te3/FeTe heterostructure with the step-flow epitaxy method and studied the topological properties of this system by using angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy.We observed the coexistence of robust superconductivity and edge states on the single QL Bi2Te3 islands which can be potential evidence for topological superconductor.
文摘Flower-like Bi2Te3 nanostructures were successfully synthesised for the first time by a simple magnetron technique or D.C. sputtering method. The phase and morphology of the products were characterized by X-ray diffraction （XRD）, manning electron microscope （SEM） and atomic force microscope （AFM）. It was found that the as-deposited Bi2Te3 has a well re-crystallized Rhombohedral phase and consisted of a wealth of flower-like structure, also the thermo-electric properties of Bi2Te3 were examined and we find that the Seebeck coefficient is 136.6μ volt/K.
文摘Superlattice nanowires are expected to show further enhanced thermoelectric performance compared with conventional nanowires or superlattice thin films. We report the epitaxial growth of high density Bi2Te3/Sb superlattice nanowire arrays with a very small bilayer thickness by pulse electrodeposition. Transmission electron microscopy, selected area electron diffraction and high resolution transmission electron microscopy were used to characterize the superlattice nanowires, and Harman technique was employed to measure the figure of merit （ZT） of the superlattice nanowire array in high vacuum condition. The superlattice nanowire arrays exhibit a ZT of 0.15 at 330 K, and a temperature difference of about 6.6 K can be realized across the nanowire arrays.
