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1.
The bias dependent interface charge is considered as the origin of the observed non-ideality in current–voltage and capacitance–voltage characteristics. Using the simplified model for the interface electronic structure based on defects interacting with the continuum of interface states, the microscopic origin of empirical parameters describing the bias dependent interface charge function is investigated. The results show that in non-ideal metal–semiconductor contacts the interface charge function depends on the interface disorder parameter, density of defects, barrier pinning parameter and the effective gap center. The theoretical predictions are tested against several sets of published experimental data on bias dependent ideality factor and excess capacitance in various metal–semicoductor systems. 相似文献
2.
X.S. Cai 《Applied Surface Science》2006,252(8):2776-2781
SiGe/Si quantum wells (QWs) with different Boron doping concentrations were grown by molecular beam epitaxy (MBE) on p-type Si(1 0 0) substrate. The activation energies of the heavily holes in ground states of QWs, which correspond to the energy differences between the heavy hole ground states and Si valence band, were measured by admittance spectroscopy. It is found that the activation energy in a heavily doped QW increases with doping concentration, which can be understood by the band alignment changes due to the doping in the QWs. Also, it is found that the activation energy in a QW with a doping concentration of 2 × 1020 cm−3 becomes larger after annealing at a temperature of 685 °C, which is attributed to more Boron atoms activation in the QW by annealing. 相似文献
3.
Mizuhiko Saeki 《Physica A》2010,389(18):3720-1903
The non-equilibrium thermo-field dynamics proposed by Arimitsu and Umezawa are generalized to the case of a non-bilinear unperturbed Hamiltonian which includes not only a bilinear part but also a non-bilinear part with momentum mixing. The forms of the quasi-particle operators for a semi-free boson field are derived. The form of the two-point Green’s function for the semi-free boson field is evaluated. A form of the admittance for a boson system interacting with its heat reservoir, which includes effects of the initial correlation and memory, is derived using the TCLE method formulated in terms of generalized non-equilibrium thermo-field dynamics. The expressions of the zeroth-order, first-order and second-order parts of the admittance in powers of the boson-boson interaction, are derived. 相似文献
4.
We examined the ac transport attribute of the multi-terminal structures in the absence and presence of magnetic field. We found that the ac response depends on the structural configurations and that the admittance varies with the features of the attached nanoribbons. In the vicinity of Dirac point the dc conductance manifests a dip or peak and the imaginary part (emittance) vanishes or not, depending on whether the attached ribbon is semiconductive or metallic. In the presence of magnetic field, the emittance becomes asymmetric reflecting the dynamic behaviors of electron and hole. 相似文献
5.
This paper presents an inverse formulation of the acoustic boundary value problem featuring arbitrary admittance boundary conditions. The problem is discretised by using finite elements to reconstruct the sound pressure field of a cavity based on a preferably small number of measurements. For that, a modal approach is investigated to handle the generally under-determined and ill-conditioned system of equations. The viability of the algorithm is tested to reconstruct sound pressure field inside a two-dimensional sedan passenger compartment. 相似文献
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Out‐of‐Equilibrium Fluctuation‐Dissipation Relations Verified by the Electrical and Thermoelectrical AC‐Conductances in a Quantum Dot 下载免费PDF全文
Adeline Crépieux 《Annalen der Physik》2017,529(9)
The electrical and heat currents flowing through a quantum dot are calculated in the presence of a time‐modulated gate voltage with the help of the out‐of‐equilibrium Green function technique. From the first harmonics of the currents, we extract the electrical and thermoelectrical trans‐admittances and ac‐conductances. Next, by a careful comparison of the ac‐conductances with the finite‐frequency electrical and mixed electrical‐heat noises, we establish the fluctuation‐dissipation relations linking these quantities, which are thus generalized out‐of‐equilibrium for a quantum system. It is shown that the electrical ac‐conductance associated to the displacement current is directly linked to the electrical noise summed over reservoirs, whereas the relation between the thermoelectrical ac‐conductance and the mixed noise contains an additional term proportional to the energy step that the electrons must overcome when traveling through the junction. A numerical study reveals however that a fluctuation‐dissipation relation involving a single reservoir applies for both electrical and thermoelectrical ac‐conductances when the frequency dominates over the other characteristic energies. 相似文献
8.
Metal–insulator–semiconductor structures based on n-Hg1−xCdxTe (x = 0.19–0.25) were grown by molecular-beam epitaxy on the GaAs (0 1 3) substrates. Near-surface graded-gap layers with high CdTe content were formed on both sides of the epitaxial HgCdTe. Admittance of these structures was studied experimentally in a wide temperature range (8–150) K. It is shown that an increase in the composition of the working layer and a decrease in temperature lead to a decrease in the frequency of transition to high-frequency behavior of the capacitance–voltage characteristics. The differential resistance of space charge region in the strong inversion increases with the composition of the working layer and for x = 0.22 and 0.25, the differential resistance is limited by the Shockley-Read generation. The values of the differential resistance of space charge region at different frequencies and temperatures were found. 相似文献
9.
Samares Kar 《Applied Surface Science》2006,252(11):3961-3967
An admittance spectroscopy technique has been developed for the interfaces between organic monolayers and silicon. The present work involves the development of an effective equivalent circuit to represent the silicon/organic-monolayer system, and the development of a parameter extraction procedure, which yields the monolayer capacitance and the monolayer thickness, the flat-band voltage, the silicon doping density, the silicon surface potential, the interface trap density, the interface trap capture cross-section and the interface trap energy. This technique was applied to three types of silicon/organic-monolayer system. 相似文献
10.
The effects of the electrochemical capacitance on the ac admittance phase of a quantum point contact
We investigate the ac admittance of a quantum point contact (QPC) in quantum hall regime. Experiment data shows that the phase of the QPC admittance is not transmission independent. With the increasing of the QPC transmission, the phase increases in large magnetic field, but stays constant in small field. The theoretical works indicated that the Coulomb interaction between the counter-propagate channels is the main reason for the non-constant phase in large field. Besides this, we also studied the other types of Coulomb interactions. Especially, the Coulomb interaction between the channels across the QPC could make the sample behave like a capacitance and thus a change from the capacitive behavior to inductive behavior is expected when the QPC is opening. Our investigation demonstrates that the Coulomb interaction can serve as a sensitive detection method for the internal properties of quantum devices, in particular, at gigahertz frequencies. 相似文献