arXiv subjects

Hong-Seok Kim

Publications and source records attributed to Hong-Seok Kim.

22 records · Page 2Linked to original sources

arXiv2015

Gate-tunable superconducting quantum interference devices of PbS nanowires

We report on the fabrication and electrical transport properties of gate-tunable superconducting quantum interference devices (SQUIDs), made of semiconducting PbS nanowire contacted with PbIn superconducting electrodes. Applied with a magnetic field perpendicular to the plane of the nano-hybrid SQUID, periodic oscillations of the critical current due to the flux quantization in SQUID are observed up to T = 4.0 K. Nonsinusoidal current-phase relationship is obtained as a function of temperature and gate voltage, which is consistent with a short and diffusive junction model.

cond-mat.mes-hall↗

arXiv2015

Quantum interference effects in chemical vapor deposited graphene

We report several quantum interference effects in graphene grown by chemical vapor deposition. A crossover between weak localization and weak antilocalization effects is observed when varying the gate voltage and we discuss the underlying scattering mechanisms. The characteristic length scale for phase coherence is compared with that estimated from universal conductance fluctuations in the microporeformed graphene sample. These extensive temperature- and gate-dependent measurements of the intervalley and intravalley scattering lengths provide important and useful insight for the macroscopic applications of graphene-based quantum devices.

cond-mat.mes-hall↗

arXiv2015

Quantum electrical transport properties of topological insulator Bi2Te3 nanowires

We investigate the quantum transport properties of surface electrons on a topological insulator Bi2Te3 nanowire in a magnetotransport study. Although the nanowires are synthesized by using a relatively coarse method of electrochemical deposition, clear Aharonov-Bohm oscillations of phases 0 and pi are observed, owing to the highly coherent surface electron channel. The oscillation amplitude exhibits exponential temperature dependence, suggesting that the phase coherence length L_phi is inversely proportional to the temperature, as in quasi-ballistic systems. In addition, a weak antilocalization analysis on the surface channel by using a one-dimensional localization theory, enabled by successful extraction of the surface contribution from the magnetoconductance data, is provided in support of the temperature dependence of L_phi.

cond-mat.mes-hall↗

arXiv2015

Hot Carrier Trapping Induced Negative Photoconductance in InAs Nanowires toward Novel Nonvolatile Memory

We report a novel negative photoconductivity (NPC) mechanism in n-type indium arsenide nanowires (NWs). Photoexcitation significantly suppresses the conductivity with a gain up to 10^5. The origin of NPC is attributed to the depletion of conduction channels by light assisted hot electron trapping, supported by gate voltage threshold shift and wavelength dependent photoconductance measurements. Scanning photocurrent microscopy excludes the possibility that NPC originates from the NW/metal contacts and reveals a competing positive photoconductivity. The conductivity recovery after illumination substantially slows down at low temperature, indicating a thermally activated detrapping mechanism. At 78 K, the spontaneous recovery of the conductance is completely quenched, resulting in a reversible memory device which can be switched by light and gate voltage pulses. The novel NPC based optoelectronics may find exciting applications in photodetection and nonvolatile memory with low power consumption.

cond-mat.mes-hall↗