Kangliang Wei

A physical based analytic model of RRAM operation for circuit simulation

A physical based analytic model of metal oxide based RRAM cell under DC and pulse operation modes is presented. In this model, the transport behaviors of oxygen vacancies and oxygen ions, metal conductivity, electron hopping and heat conduction and the parasitic capacitance and resistance effects are covered. The developed analytic model is verified and calibrated by measured data. Furthermore, we implement the analytic model in a 2×2 RRAM array simulation and investigate the reliability of RRAM array for the first time.

Physically Based Evaluation of Electron Mobility in Ultrathin-Body Double-Gate Junctionless Transistors

In this letter, we presented theoretical results on the low-field electron mobility of ultrathin-body double-gate junctionless transistors. A 1D Poisson-Schrödinger problem perpendicular to the gate is self-consistently solved to get the electron wavefunctions, and the Kubo-Greenwood formula with consideration of phonon, surface roughness, and ionized impurity scattering is employed to evaluate the corresponding mobility components. The dependence of mobility on silicon layer thickness and doping concentration is also investigated.

Mixed-Mode Analysis of Different Mode Silicon Nanowire Transistors-Based Inverter

In this paper, we focused on the comparison and analysis of the performance of inversion-mode (IM), accumulation-mode (AM), and junctionless (JL) silicon nanowire field-effect transistors (NWTs)-based inverter. The effects of the radius, equivalent oxide thickness and source/drain doping in the different mode nanowire device structure are investigated. The capacitance components and transient characteristics, which determine the behavior of devices in the circuits, are studied and compared among different mode nanowire devices. The mixed-mode circuit simulations have been performed for the inverter circuit and three-stage ring oscillator consist of n-type and p-type IM/AM/JL NWTs. JL NWTs show lower Miller capacitance which contributes to suppressing the overshoot effect in the circuits. Results of these simulations can give insights into the in-circuit behavior of these future generation devices.

Random interface trap induced fluctuation in 22nm high-k/metal gate junctionless and inversion-mode FinFETs

The impact of random interface trap (RIT) on the junctionless MOSFET (JL-FET) is investigated. Both acceptor-like and donor-like interface traps are considered to 22nm high-k metal gate (HKMG) junctionless structure and traditional inversion-mode FinFET. Fluctuations in threshold voltage, on current, leakage current, drain induced barrier lowering and subthreshold swing are analyzed. The results show that the position effect and type of interface traps (ITs) can induce different fluctuation for JL-FET and FinFET.

Investigation of Hole Mobility in Strained InSb Ultrathin Body pMOSFETs

Hole mobility in strained ultrathin body InSb-on-insulator (InSb-OI) devices is calculated by a microscopic approach. The anisotropic valence band structures, in consideration of quantum confinement, are obtained via solving the six-band k· p Schrödinger and Poisson equations self-consistently. Hole mobility is calculated using the Kubo-Greenwood formula accounting for nonpolar acoustic and optical phonons, polar optical phonons, and surface roughness scatterings. The models are calibrated and verified with experimental data. The influences of body thickness and strain effect, including both biaxial and uniaxial strains, are investigated in InSb-OI devices. Our results indicate that mobility degradation occurs in both single-gate (SG) and double-gate (DG) mode when body thickness scales down below a certain range. Moreover, mobility in the DG mode outperforms that in the SG for thick body thickness, but loses its superiority over SG for extremely thin body. Compressive strain is favorable to hole mobility. Furthermore, more enhancement is achieved by uniaxial strain than biaxial strain.

An adaptive grid algorithm for self-consistent k·p Schrodinger and Poisson equations in UTB InSb-based pMOSFETs

Hole mobility in ultra-thin body (UTB) InSb-OI devices is calculated by a microscopic approach. An adaptive grid algorithm is employed to discretize 2-D k space. The accurate valence band structures are obtained via solving the 6-band k·p Schrödinger and Poisson equations self-consistently. Hole mobility is computed using the Kubo-Greenwood formalism accounting for nonpolar acoustic and optical phonons, polar optical phonons, and surface roughness scattering mechanisms.

Calculation of the valence band structure in strained In 0.7 Ga 0.3 As devices with different surface orientation

Using the eight-band k·p Hamiltonian approach, the valence band structure of strained In0.7Ga0.3As is calculated for (001), (110) and (111) orientation. The impact of biaxial strain and uniaxial strain on energy band splitting and warping is investigated. The dependency of the valence band structure on the surface electric field and body thickness is also studied in this work.

A compact model of resistive switching devices

In this paper a compact model both for bipolar and unipolar resistive switching device is proposed. Basic I–V characteristics of RRAM are easily and correctly represented by this model. The model is verified by the bipolar RRAM experiment results. The model can be used as simple and fast tool to design and optimize RRAM.

Impact of Random Interface Traps and Random Dopants in High-

In this paper, the fluctuation of random interface traps (RITs) and its interaction with random dopants of 22-nm junctionless FETs (JL-FET) with high- k/metal gate (HKMG) are investigated with 3-D statistical TCAD simulations. The impacts of RIT and random dopant fluctuation (RDF) on the performances of JL-FET are evaluated separately and together. The results show that acceptor-like interface traps mainly affect the drive current, while donor-like interface traps have a significant impact on the subthreshold region. RIT and RDF have different impacts on device performance. Although the influence of RDF is larger than RIT, the impact of RIT cannot be neglected due to their strong correlation. The variation induced by RIT and RDF should be taken into account simultaneously for HKMG JL-FETs.

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3D paralleled electro-thermal coupled full band ensemble MC simulation platform is developed for analysis of local heating effect on performance and reliability of semiconductor devices. This new developed simulation platform provides a powerful tool for thermal-aware device and circuit design of nano scale devices.