我们仔细研究了少层电荷密度波（CDW）2 H-TaS 2器件的输运和电容特性。不同器件的CDW转变温度和阈值电压不同，这归因于这些基于少层2 H-TaS 2薄片的微器件的层间相互作用和不均匀的局部缺陷。在我们的实验中，2 H-TaS_2器件在低温下观察到半导体性质而不是金属性质。对于存在CDW的不同测量器件，相对阈值电压的温度依赖性可以缩放到（1- T / Tr）^0.5 +delta，其中delta=0.08。同时进行电导-电压和电容-电压测量。在很低的交流有源电压下，我们发现这两种测量的磁滞回线完全匹配。我们的结果指出，电容-电压测量也可以用来确定CDW的阈值脱钉电压，这为我们研究CDW提供了一种新的方法。
英文摘要：
We carefully investigated the transport and capacitance properties of few layer charge density wave (CDW) 2H-TaS2 devices. The CDW transition temperature and the threshold voltage vary from device to device, which is attributed to the interlayer interaction and inhomogeneous local defects of these micro-devices based on few layer 2H-TaS2 flakes. Semiconductivity rather than metallic property of 2H-TaS2 devices was observed in our experiment at low temperature. The temperature dependence of the relative threshold voltage can be scaled to (1- T / Tr )^0.5+delta with delta=0.08 for the different measured devices with presence of the CDWs. The conductance-voltage and capacity-voltage measurements were performed simultaneously. At very low ac active voltage, we found that the hysteresis loops of these two measurements exactly match each other. Our results point out that the capacity-voltage measurements can also be used to define the threshold depinning voltage of the CDW, which give us a new method to investigate the CDWs.
Van der Waals moiré materials have emerged as a highly controllable platform to study the electronic correlation phenomena. In particular, robust correlated insulating states have recently been discovered at both integer and fractional filling factors of the semiconductor moiré systems. Here, we reveal the thermodynamic properties of these states by measuring the gate capacitance of MoSe2/WS2 moiré superlattices. We observe a series of incompressible states for filling factor 0 - 8 and anomalously large capacitance (nearly 60% above the device's geometrical capacitance) in the intervening comp…
We present a physics-based circuit-compatible model for double-gated two-dimensional semiconductor based field effect transistors, which provides explicit expressions for the drain current, terminal charges and intrinsic capacitances. The drain current model is based on the drift-diffusion mechanism for the carrier transport and considers Fermi-Dirac statistics coupled with an appropriate field-effect approach. The terminal charge and intrinsic capacitance models are calculated adopting a Ward-Dutton linear charge partition scheme that guarantees charge-conservation. It has been implemented in…
Capacitance and charge relaxation resistance of chaotic cavities - Joint distribution of two linear statistics in the Laguerre ensemble of random matrices
A Metal-dielectric-topological insulator capacitor device based on hBN-encapsulated CVD grown Bi2Se3 is realized and investigated in the radio frequency regime. The RF quantum capacitance and device resistance are extracted for frequencies as a high as 10 GHz, and studied as a function of the applied gate voltage. The combination of the superior quality hBN dielectric gate with the optimized transport characteristics of CVD grown Bi2Se3 (n~10^18cm-3 in 8 nm) allow us to attain a bulk depleted regime by dielectric gating. A quantum capacitance minimum is observed revealing a purely Dirac regime…
Designable electron transport features in one-dimensional arrays of metallic nanoparticles: Monte Carlo study of the relation between shape and transport
On-chip superconducting GHz RF reflectometry of the capacitance response in bilayer graphene
DGIST Research Institute, DGIST（大邱冈科学技术院研究院）；Department of Physics and Chemistry, DGIST（大邱冈科学技术院物理化学系）；Quantum Technology Institute, Korea Research Institute of Standards and Science（韩国标准科学研究院量子技术研究所）；Industrial AX Innovation Research Institute and Sensor Technology Support Center, DGIST（大邱冈科学技术院工业AX创新研究所和传感器技术支持中心）；Research Center for Materials Nanoarchitectonics, National Institute for Materials Science（物质材料研究机构材料纳米结构研究中心）；Research Center for Electronic and Optical Materials, National Institute for Materials Science（物质材料研究机构电子光学材料研究中心）；Department of Physics, Kyungpook National University（庆北大学物理系）；Department of Interdisciplinary Engineering, DGIST（大邱冈科学技术院交叉工程系）
We have decomposed the modeling of the field-effect transistors into the two independent parts: the current continuity based kinetics and the charge neutrality based electrostatics. The former part, that is universal for all FETs, leads to an explicit and closed form of I-V characteristics as a function of the total channel charge. The latter part, which is specific for a particular material and geometric configurations can be considered as an independent engineering task. The quantum capacitance and the interface trap density are consistently incorporated into the solution of the current cont…
Small-signal model for 2D-material based field-effect transistors targeting radio-frequency applications: the importance of considering non-reciprocal capacitances
When transistor gate insulators have nanometer-scale equivalent oxide thickness (EOT), the gate capacitance ($C_\textrm{G}$) becomes smaller than the oxide capacitance ($C_\textrm{ox}$) due to the quantum capacitance and charge centroid capacitance of the channel. Here, we study the capacitance of monolayer MoS$_\textrm{2}$ as a prototypical two-dimensional (2D) channel while considering spatial variations in the potential, charge density, and density of states. At 0.5 nm EOT, the monolayer MoS$_\textrm{2}$ capacitance is smaller than its quantum capacitance, limiting the single-gated $C_\text…
BiSbTeSe$_2$ is a 3D topological insulator (3D-TI) with Dirac type surface states and low bulk carrier density, as donors and acceptors compensate each other. Dominating low temperature surface transport in this material is heralded by Shubnikov-de Haas oscillations and the quantum Hall effect. Here, we experimentally probe and model the electronic density of states (DOS) in thin layers of BiSbTeSe$_2$ by capacitance experiments both without and in quantizing magnetic fields. By probing the lowest Landau levels, we show that a large fraction of the electrons filled via field effect into the sy…
We theoretically explore mechanisms that can potentially give rise to the steady-state and transient negative capacitance in a uniaxial ferroelectric film stabilized by a dielectric layer. The analytical expressions for the steady-state capacitance of a single-domain and poly-domain states are derived within Landau-Ginzburg-Devonshire approach and used to study the state stability vs. the domain splitting as a function of dielectric layer thickness. Analytical expressions for the critical thickness of the dielectric layer, polarization amplitude, equilibrium domain period and susceptibility ar…
Coupled quantum Hall edge channels show intriguing non-trivial modes, for example, charge and neutral modes at Landau level filling factors 2 and 2/3. We propose an appropriate and effective model with Coulomb interaction and disorder-induced tunneling characterized by coupling capacitances and tunneling conductances, respectively. This model explains how the transport eigenmodes, within the interaction- and disorder-dominated regimes, change with the coupling capacitance, tunneling conductance, and measurement frequency. We propose frequency- and time-domain transport experiments, from which …
We suggest a possible realization of a solid-state memory capacitive (memcapacitive) system. Our approach relies on the slow polarization rate of a medium between plates of a regular capacitor. To achieve this goal, we consider a multi-layer structure embedded in a capacitor. The multi-layer structure is formed by metallic layers separated by an insulator so that non-linear electronic transport (tunneling) between the layers can occur. The suggested memcapacitor shows hysteretic charge-voltage and capacitance-voltage curves, and both negative and diverging capacitance within certain ranges of …
