Single crystal

About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.

Electronic transport properties of single-crystal bismuth nanowire arrays

Abstract: We present here a detailed study of the electrical transport properties of single-crystal bismuth nanowire arrays embedded in a dielectric matrix. Measurements of the resistance of Bi nanowire arrays with different wire diameters (60\char21{}110 nm) have been carried out over a wide range of temperatures (2.0\char21{}300 K) and magnetic fields (0\char21{}5.4 T). The transport properties of a heavily Te-doped Bi nanowire array have also been studied. At low temperatures, we show that the wire boundary scattering is the dominant scattering process for carriers in the undoped single-crystal Bi nanowires, while boundary scattering is less important for a heavily Te-doped sample, consistent with general theoretical considerations. The temperature dependences of the zero-field resistivity and of the longitudinal magneto-coefficient of the Bi nanowires were also studied and were found to be sensitive to the wire diameter. The quantum confinement of carriers is believed to play an important role in determining the overall temperature dependence of the zero-field resistivity. Theoretical considerations of the quantum confinement effects on the electronic band structure and on the transport properties of Bi nanowires are discussed. Despite the evidence for localization effects and diffusive electron interactions at low temperatures $(Tl~4.0\mathrm{K}),$ localization effects are not the dominant mechanisms affecting the resistivity or the magnetoresistance in the temperature range of this study.

Pressure-induced superconductivity in topological parent compound Bi2Te3

Abstract: We report a successful observation of pressure-induced superconductivity in a topological compound Bi2Te3 with Tc of ∼3 K between 3 to 6 GPa. The combined high-pressure structure investigations with synchrotron radiation indicated that the superconductivity occurred at the ambient phase without crystal structure phase transition. The Hall effects measurements indicated the hole-type carrier in the pressure-induced superconducting Bi2Te3 single crystal. Consequently, the first-principles calculations based on the structural data obtained by the Rietveld refinement of X-ray diffraction patterns at high pressure showed that the electronic structure under pressure remained topologically nontrivial. The results suggested that topological superconductivity can be realized in Bi2Te3 due to the proximity effect between superconducting bulk states and Dirac-type surface states. We also discuss the possibility that the bulk state could be a topological superconductor.

Growth of 2 inch ZnO bulk single crystal by the hydrothermal method

Abstract: Zinc oxide (ZnO) single crystals were grown by the hydrothermal method using a platinum inner container. The 2 inch ZnO wafers obtained from these bulk crystals possess an extremely high crystallinity and purity. The electrical resistivity is highly uniform over the entire wafer area. After annealing, the step-and-terrace structure was observed on the surface of the wafer. The etch pit density was decreased to less than 80 cm−2. These results suggest that these 2 inch ZnO wafers are suitable for wide band gap device applications.

Facile Synthesis of Single Crystal PtSe2 Nanosheets for Nanoscale Electronics.

Abstract: Ultrathin single crystal platinum diselenide (PtSe2 ) nanosheets are synthesized using H2 PtCl6 and Se as the precursors. The electronic properties are first investigated and exhibit p-type transport behavior with the mobility much larger than 7 cm2 V-1 s-1 . The further investigation on PtSe2 /MoS2 var der Waals p-n junction demonstrated that PtSe2 could be potentially applied in 2D electronics.

Ultrafast ion migration in hybrid perovskite polycrystalline thin films under light and suppression in single crystals

Abstract: Understanding the influence of light on ion migration in organic–inorganic halide perovskite (OIHP) materials is important to understand the photostability of perovskite solar cells. We reveal that light could greatly reduce the ion migration energy barrier in both polycrystalline and single crystalline OIHP. The activation energies derived from conductivity measurement under 0.25 Sun decrease to less than one half of the values in the dark. A typical ion drift velocity in CH3NH3PbI3 polycrystalline films is 1.2 μm s−1 under 1 Sun, compared with 0.016 μm s−1 under 0.02 Sun. Ion migration across the photoactive layers in most OIHP devices thus takes only subseconds under 1 Sun illumination, which is much shorter than what it was thought to take. Most important of all, ion migration through a single crystal surface is still too slow to be observed even after illumination for two days due to the large ion diffusion activation energy, >0.38 eV.