Under-barrier leakage of the quantum-mechanical current density owing to the interference of electron waves in the 2D semiconductor nanostructures

The theoretical analysis of the under-barrier leakage of the local quantum-mechanical current density in the 2D semiconductor nanostructures that represent narrow and wide rectangular quantum wells sequentially located along the propagation direction of electron wave is presented. The wave arrives from the narrow quantum well at a semi-infinite rectangular potential barrier with height V ₀ in the wide quantum well. Under certain conditions, the exponentially decaying and coordinate-dependent leakage of the local quantum-mechanical current density under barrier is allowed for the waves with energies of less than V ₀ due to the interference of electron waves in such a nanostructure.     

Quantum-mechanical suppression and enhancement of SCEs in ultrathin SOI MOSFETs

This paper simulates the transport characteristics of ultrathin silicon-on-insulator MOSFETs, and evaluates the influence of the quantum-mechanical mechanism on the short-channel effects on the basis of the density-gradient model. It is clearly shown that the quantum-mechanical mechanism suppresses the buried-insulator-induced barrier lowering with regard to the subthreshold swing because the surface dark space yields a high-field region in the source region adjacent to the channel. It is also suggested that the quantum-mechanical mechanism enhances the impact of the apparent charge-sharing effect on the threshold voltage because the surface dark space effectively increases the thickness of the gate-oxide layer and buried-oxide layer.     

The value of the third-person effect in theory building

The third-person effect sheds light on the self–other discrepancy in perceived media effects on subsequent behavioral consequences. Despite the practical impetus and growing theoretical interest in the third-person effect, very little attention has been given to evaluating its value and efficacy for a more rigorous theory construction. The current research embraces a holistic approach to assess the worth of the third-person effect in theory building based on the six criteria for the evaluation of theory: explanatory power, predictive power, heuristic value, parsimony, testability, and internal consistency. Building on the discussion of its theoretical merits and limitations, new agendas for the third-person effect research are proposed.     

A 2D threshold-voltage model for small MOSFET with quantum-mechanical effects

A threshold condition different from the classical one is proposed for MOSFET with quantum effects, and is based on self-consistent numerical solution of the Schrödinger’s and Poisson’s equations. Furthermore, an accurate 1D threshold-voltage model including polysilicon-depletion effects is built by experimental fitting. Simulated results exhibit good agreement with measurement data. Based on this 1D model, a 2D quantum-modified threshold-voltage model for small MOSFET is developed by solving the quasi-2D Poisson’s equation and taking short-channel effects and quantum-mechanical effects into consideration. The model can also be used for deep-submicron MOSFET with high-k gate-dielectric and reasonable design of device parameters.     

Quantum corrections to threshold voltages for fully depleted SOI transistors with two independent gates

The linear charge coupling effect of threshold voltages V _th of the bottom (field) gate, i.e., a substrate of the silicon-on-insulator structure of fully depleted n-MIC transistors on a lightly doped silicon layer 20–50 nm thick, is studied depending on the voltage V _bg of the top asymmetrically biased (with negative polarity) N ⁺-poly-Si gate. It is shown that the quantum-mechanical correction conditioned by the electrostatically induced size effect of the transverse field should be considered when determining the linear charge coupling region between gates even at a silicon layer thickness of ～50 nm. An increase in the positive charge on the surface states at the heterointerface with a silicon layer increases the quantum-mechanical correction by a factor of 2–4 due to the quantum capacitance effect affecting donor-trap recharging in the case of a significant difference between the opposite-polarity potentials of the two gates.     

Effect of transverse constant electric field on the electron interference effects related to the under-barrier penetration of quantum-mechanical current density in 2D semiconductor nanostructures

The effect of transverse constant electric field F on the under-barrier penetration of the local quantum-mechanical current density in a 2D semiconductor structure is theoretically studied. The structure represents two quantum wells with identical widths that are sequentially located along the propagation direction of electron wave: the first well has the rectangular cross section, and the second well exhibits a semi-infinite rectangular potential barrier with height V ₀ that is modified by the transverse electric field. When an electron wave whose energy is less than resulting height of the potential barrier V _eff is incident from the first well on the barrier under certain conditions, the coordinate-dependent exponentially decaying penetration of the local quantum-mechanical current density may take place under the barrier due to the interference of electron waves in the nanostructure. It is demonstrated that the penetration parameters depend on field strength F.     

Monte Carlo Simulation of Nanoscale SOI MOSFETs

A comparative review is presented of the current research on the quantum-mechanical and classical Monte Carlo simulation of SOI MOSFETs. A quantum-mechanical simulation method is proposed whereby the energy of transverse channel quantization is represented by a correction term. A newly developed simulation program, called BALSOI, is outlined. A comparison is made between the results of a 2D classical Monte Carlo simulation and those obtained by the quantum-mechanical method. It is observed that the differences are much smaller than what one might expect. This finding is explained as due to the considerable effect of the space charge, which is mainly governed by the classical, longitudinal motion of carriers through the channel. An analytical formula is derived for the effect of channel quantization on the gate–channel capacitance. The strength of tunneling current through a short-channel transistor in the off state is considered.     

Backgatting effect in GaAs FETs with a channel–semi-insulating substrate boundaryAhmed Chaouki Megherbi a,*, Said Benramache b, Abderrazak Guettaf a

This study focuses on modeling the effects of deep hole traps, mainly the effect of the substrate（backgating effect） in a GaAs transistor MESFT. This effect is explained by the existence, at the interface, of a space charge zone. Any modulation in this area leads to response levels trapping the holes therein to the operating temperature. We subsequently developed a model treating the channel substrate interface as an N–P junction, allowing us to deduce the time dependence of the component parameters of the total resistance R ds, the pinch-off voltage V P, channel resistance, fully open R co and the parasitic series resistance R S to bind the effect trap holes H1and H0. When compared with the experimental results, the values of the R DS（t S/ model for both traps show that there is an agreement between theory and experiment; it has inferred parameter traps, namely the density and the time constant of the trap. This means that a space charge region exists at the channel–substrate interface and that the properties can be approximated to an N–P junction.     

Quantum-based Simulation analysis of scaling in ultrathin body device structures

We present self-consistent solutions of ultrathin body device structures to understand the influence of quantum-mechanical confinement on the predictions of classical scaling theory. We show that two-dimensional (2-D) electrostatics considerations play a more dominant role than quantum-mechanical effects in the subthreshold behavior of ultrathin fully depleted silicon-on-insulator structures. We also show how modifications to the doping profile can be used to alleviate 2-D short-channel effects.     

Temperature dependent model for threshold voltage and subthreshold slope of strained-Si channel MOSFETs with a polysilicon gate

We present a temperature dependent model for the threshold voltage V_t and subthreshold slope S of strained-Si channel MOSFETs and validate it with reported experimental data for a wide range of temperature, channel doping concentration, oxide thickness and strain value. Such model includes the effect of lattice strain on material, temperature dependent effective mass of carriers, interface-trapped charge density and bandgap narrowing due to heavy channel doping. Also considered are polydepletion effects, carrier localization effect in the ultra-thin channel and quantum-mechanical effects. Our investigation reveals that the threshold voltage reduces linearly with increasing temperature whereas the subthreshold slope increases. In addition V_t is found to be sensitive to strain while S is weakly dependent on strain. Moreover, the channel doping concentration influences both V_t and S, and also the rate of change of V_t with temperature. Furthermore, S decreases for a lightly doped channel particularly at lower temperatures.     

Comparison of modulation doped effect in negative differential resistance field effect transistors (NDRFETs)

N-shaped negative differential resistance field effect transistors (NDRFETs) have been fabricated and demonstrated. The interesting N-shaped NDRs are three terminal controlled phenomena. This N-shaped NDR behavior is found in the higher drain-to-source voltage (V_DS) regime and is obtained both at positive and negative gate-to-source bias (V_GS). We believe that the NDR phenomena are attributed to the real space transfer (RST) effect. Due to the modulation doped effect and different barrier height, the NDR behavior can easily be controlled. The influence of V_GS bias on the NDR characteristics is also investigated.     

Improved dislocation model of silicon solar cells with the effect of front and back surface recombination velocity

We have extended a previous model for calculating the effects of dislocations on the characteristics of a Si solar cell to include the effects of front and back surface recombination. This improved dislocation model uses Green's function approach to solve the three‐dimensional continuity equation of the minority carriers with suitable boundary conditions corresponding to surface recombination at the n and p sides. The dislocations are considered to be localized lines, extending perpendicular to the front and back surfaces of the cell and having a recombination velocity. We discuss effect of several parameters such as bulk dislocation density, minority carrier diffusion length in p and n regions on the J‐V characteristics, and spectral response of the cell. It is shown that these results agree well with previously published, experimental data. Copyright © 2013 John Wiley & Sons, Ltd.     

Fano effect in the magnetoabsorption spectra of gallium arsenide

The magnetooptic absorption spectra of high-quality homoepitaxial GaAs layers in a magnetic field B up to 7.5 T at T=1.7 K are investigated. It is shown that the Fano effect is involved in the formation of certain lines of the magnetooptic spectrum. The parameters of the phenomenological Fano function are determined. It is shown that polariton effects of the diamagnetic exciton play a significant role in the investigated processes. Fiz. Tekh. Poluprovodn. 33, 19–24 (January 1999)     

Effect of inhomogeneities of Bi2T3 crystals on the transverse Nernst-Ettingshausen effect

The effect of inhomogeneities in p-Bi₂Te₃ crystals, grown by different methods, on the coefficients of the transverse Nernst-Ettingshausen and Hall effects has been studied. The degree of homogeneity of the crystals was estimated on the basis of thermo-emf (Seebeck coefficient) data. It was established that the concentration dependences of the Nernst-Ettingshausen coefficient at T=300 K in homogeneous and inhomogeneous samples are different. This makes it possible to use the Nernst-Ettingshausen effect data for quality assessment of Bi₂Te₃ crystals. It is shown that the anomalous drop of the Hall coefficient with increasing temperature in a number of samples is due to inhomogeneities, and in Sn-doped Bi₂Te₃ crystals it is due to the existence of an impurity level against the background of the valence-band states. Fiz. Tekh. Poluprovodn. 31, 441–443 (April 1997)     

A study of metamorphic HEMT technological improvements: Impact on parasitic effect electrical models

Metamorphic high electron mobility transistor (MHEMT) technology is well adapted to optical high bit rate telecommunication systems. In this context, we propose in this paper a global analysis of this technology in order to verify if it is suitable for system conditions in terms of on-state and off-state breakdown voltages, f_t and f_max, … Our interest concerns the transistor parasitic effects and their impact on the amplifier circuit performances, considering the transistor role in transmitter and receiver modules. We propose new electrical models for each experimentally measured parasitic effect and they could be added to the MHEMT basic models for circuit design.     

Impact of interface traps on gate-induced drain leakage current in n-type metal oxide semiconductor field effect transistor

As the features sizes of metal oxide semiconductor field effect transistor (MOSFET) are aggressively scaled into the submicron domain, hot carriers generated by the very large electric fields of drain region create serious reliability problems for the integrated circuit in MOS technology. The charges trapping in the gate oxide and the defects at the Si/SiO₂ interface have also undesirable effects on the degradation and ageing of MOSFET. Among the problems caused by these effects is the band-to-band tunnelling (BBT) of hot carriers in the gate-to-drain overlap region which is the source of the gate-induced drain leakage current I _gidl. The oxide charges shift the flat-band voltage and result in an enhancement of the I _gidl current. On the other hand, the generation of interface traps introduce an additional band-trap-band (BTB) leakage mechanism and lead to a significant increase ?I _gidl in a drain leakage current. In this work we propose a new method to calculate the I _gidl current which takes into account of the BTB leakage mechanism in order to clarify the impact of interface traps located in the gate-to-drain overlap region on the I _gidl current.     

Synthesis of a novel organic nonlinear optical chromophore and the Testing for μgβ Value

Much attention has been devoted to nonlinear optica (NLO) materials over the past decade because of the poten tial applications in the field of telecommunications, optica signal processing, optical switching, and so forth. Organi NLO materials with high p…     

Nanoelectronics [quantum electron devices]

The dimensions of semiconductor devices can now be reduced to the point where quantum-mechanical effects must be considered in device performance. New device concepts have therefore been proposed, and already realised, in which quantum-mechanical effects are used to achieve increased electron mobilities or in which interference phenomena are utilised. At present, the major drawbacks of nanoelectronics are the technological problems of realising the devices. The emphasis of the paper is on new technological concepts for device realisation. Additionally, an overview of proposed and realised devices is given. Future advances in nanofabrication may come from the development of the scanning tunnelling microscope and related systems     

The effect of a quantizing electric field on the transverse mobility of electrons in a superlattice

The effect of a quantizing static electric field parallel to the axis of a semiconductor superstructure on the charge-carrier mobility in the direction perpendicular to this axis is studied. The transverse conductivity of charge carriers was calculated on the basis of a quantum-mechanical kinetic equation. Using the results of the numerical analysis, the dependences of the time of the carriers’ momentum relaxation on their transverse energy and also the dependences of the charge-carrier mobility on the strength of the longitudinal quantizing electric field were plotted. It is shown that the dependence of the density of current flowing perpendicularly to the superlattice axis on the strength of the longitudinal electric field is oscillatory.     

THEORETICAL ANALYSIS OF THE PRESSUREMAGNETO-ELECTRIC EFFECT OF JFET

In this paper the pressure-magneto-electric effect of Junction Field Effect Transistor(JFET)is discussed by using standard relaxation techniques.A theoretical evaluation of thepressure sensitivity and Hall sensitivity of the n-channel silicon JFET with various geometries(W/L),gate voltages(V_(FS))and drain voltages(V_(DS))is made.The results show that whenP≠0,B=0,the current-pressure sensitivity is about 2.5%.cm~2/N,supposing W/L(?)1/2-1.Based on that,a junction field effect pressure sensor with high stability and low noise is designed.