Quantum capacitance

About: Quantum capacitance is a research topic. Over the lifetime, 954 publications have been published within this topic receiving 24165 citations.

Fringe field control of one-dimensional room temperature sub-band resolved quantum transport in site controlled AlGaN/GaN lateral nanowires

Abstract: We have demonstrated effective fringe field control of one-dimensional electron gas (1-DEG) in AlGaN/GaN lateral nanowires The nanowires are site controlled and formed by a combination of dry and anisotropic wet etching The nanowire dimensions are well controlled and can have a very high length/width aspect ratio of 10 μm/5 nm or larger The transport is controlled by a fringe gate and shows room temperature quantum transport where gradual filling of 1-D subbands gets manifested as oscillations in the transconductance The fringe gate threshold voltage for depletion of one-dimensional electron gas is found to increase with increasing drain voltage indicating efficient control of 1-DEG The transport characteristics and fringe field operation are explained by taking into account quantum capacitance in addition to the conventional geometric capacitance The effect of nanowire width and fringe gate position is also discussed

A current-voltage model for Schottky-barrier graphene based transistors

Abstract: A low complexity computational model of the current-voltage characteristics for graphene nano-ribbon (GNR) field effect transistors (FET), able to simulate a hundred of points in few seconds using a PC, is presented. For quantum capacitance controlled devices, self-consistent calculations of the electrostatic potential can be skipped. Instead, analytical closed-form electrostatic potential from Laplace's equation yields accurate results compared with that obtained by self-consistent Non-Equilibrium Green's Functions (NEGF) method. The model includes both tunnelling current through the Schottky barrier (SB) at the contact interfaces and thermionic current above the barrier, properly capturing the effect of arbitrary physical and electrical parameters.

Capacitance-voltage spectroscopy of silicon nanodots

Abstract: Frequency-dependent capacitance-voltage spectroscopy was applied to investigate the carrier transport dynamics in a silicon nanodots resonant tunneling device structure. Two negative differential resistance (NDR) regions in the current-voltage characteristics were found in this investigated structure. Two anomalous regions were also found in the capacitance-voltage spectroscopy, which coincide with the NDR regions in the current-voltage characteristics. The origin of the anomalous phenomenon was attributed to the mesoscopic quantum capacitance due to the holes transport through the energy states associated with the Si nanodots. An equivalent circuit model was proposed to quantitatively evaluate the frequency dependence of the capacitance-voltage spectroscopy.

A novel compact model of quantum effects in scaled SOI and double-gate MOSFETs

Abstract: Quantum-mechanical (QM) confinement of inversion-layer carriers significantly affects the threshold voltage and gate capacitance of highly scaled MOSFETs. In bulk-Si and partially depleted (PD) SOI (n)MOSFETs, the confinement is in the potential well defined by the gate-oxide barrier (which is virtually infinite) and the silicon conduction (or valence) band (the steep gradient of which defines the high transverse electric field, which controls the effect) (Stern, 1972). In ultra-thin-film fully depleted (FD) SOI and double-gate (DG) MOSFETs, the well is defined by the front- and back-gate oxide barriers, but the quantum effect can be significantly influenced by the electric field in the Si film (Majkusiak et al, 1998). Furthermore, as the film thickness (t/sub Si/) is increased, this influence becomes predominant as in the bulk-Si and PD/SOI devices. In this paper, we present a comprehensive compact model for the quantum-confinement effects for arbitrary t/sub Si/. The model, verified by numerical simulation results obtained with a self-consistent Schrodinger-Poisson solver (SCHRED; Vasileska et al, 2000), leads to characterizations of the threshold-voltage increase due to the carrier-energy quantization and the gate-capacitance reduction due to the perturbed carrier distribution.

Spin-accumulation capacitance and its application to magnetoimpedance

Abstract: It has been known that spin-dependent capacitances usually coexist with geometric capacitances in a magnetic multilayer. However, the charge and energy storage of the capacitance due to spin accumulation (SA) has not been fully understood. Here, we resolve this problem starting from the charge storage in the spin degree of freedom: spin accumulation manifests itself as an excess of electrons in one spin channel and an equal deficiency in the other under the quasi-neutrality condition. This enables us to model the two spin channels as the two plates of a capacitor. Taking a ferromagnet/nonmagnet junction as an example and using a method similar to that for treating quantum capacitance, we find that an SA capacitance can be introduced for each layer to measure its ability to store spins. A spatial charge storage is not essential for the SA capacitor and the energy stored in it is the splitting energy of the spin-dependent chemical potentials instead of the electrostatic energy. The SA capacitance is essenti...