Bolt reinforcement is a standard reinforcement method for jointed rock masses. However, regarding rock anchoring, the mechanical characteristics of the joint surface, as well as the angle between the bolt and the joint sliding surface, are important factors that affect rock support. Therefore, to understand the influence of a set angle, length, normal load, and other conditions that affect the shear strength of bolt joints, this study uses numerical software to establish the shear sliding model of bolt rock masses and analyzes the influence of the setting conditions of the bolt on the shear strength of a bolt rock mass, which can be done by changing the setting method of the bolt and normal mechanical conditions of the sliding surface. The results show that the shear strength of the anchor joint is not affected after the anchor reaches a certain length. The angle of the anchor strongly influences the shear strength of the anchor joint, and the shear strength curve is V-shaped, where the anchor angle is less than 90°. Moreover, the shear strength curve indicates a downward trend when the anchor angle is greater than 90°, and the shear strength of the anchorage joint increases with the increase of the normal load. Under the same anchor length (4 cm) in the anchor angle and shear strength coordinate system, the shear strength curve of the single anchor is above the shear strength curve of the double anchor, which is exclusively in the local anchor angle section under the condition of a large normal load and a large anchor angle. The shear strength curve of the double anchor is above the shear strength curve of the single anchor.

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Numerical Analysis of the Influence of Bolt Set on the Shear Resistance of Jointed Rock Masses

Based on analysis on short-channel effect and drain induced barrier lowering (DIBL) effect, a threshold voltage model for high-k MOSFET's is etablished by introducing a coefficient that interrelates the two effects. Influences of various factors on threshold voltage shift are simulated and investigated, and the optimal range of k values is obtained.

Threshold Voltage Model for Deep-Submicrometer MOSFET's

A new 0.1-/spl mu/m MOSFET structure called asymmetric halo by large-angle-tilt implant (AHLATI) is proposed for substantial reduction of short-channel and hot-carrier effects while enhancing the current driving capability. This structure differs from the conventional devices in that it has an asymmetric channel profile with a localized pileup region next to the source junction.

An 0.1-/spl mu/m asymmetric halo by large-angle-tilt implant (AHLATI) MOSFET for high performance and reliability

In this work, we analyzed the subthreshold current (ID) of pocket implanted MOSFETs using extensive device simulations and experimental data. We present an analytical model for the subthreshold current applicable for any type of FET and show that the subthreshold current of nMOSFETs, which is mainly due to diffusion, is determined by the internal two-dimensional hole distribution across the device. This hole distribution is affected by the electric potential of the gate and the doping concentration in the channel. The results obtained allow accurate modelling of the subthreshold current of future generation MOS devices

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Analysis of the subthreshold current of pocket or halo-implanted nMOSFETs

An analytical subthreshold current model for metal oxide semiconductor field effect transistors (MOSFETs) with pocket implantation is presented. The model is developed based on considering an averaged localized pileup of channel dopants near the source and drain ends of channel to account for the pocket implantation effect and to derive the channel potential using a pseudo-two-dimensional (2-D) method. This, together with the conventional drift-diffusion theory, leads to the development of a subthreshold current model for pocket-implanted MOS devices. Model verification is carried out using data measured from a set of pocket-implanted NMOSFETs fabricated from a 0.17-/spl mu/m, DRAM process. Very good agreement is obtained between the model calculations and measurement results.

An analytical subthreshold current model for pocket-implanted NMOSFETs

This work reports an anomalous subthreshold characteristic of the MOSFET for the first time. It is observed that the subthreshold characteristic does not change as the channel length decreases. The cause of channel length independent subthreshold characteristics is identified as the localized pileup of channel dopants near the source and drain ends of the channel. The low surface potential of this pileup region limits the subthreshold current of MOSFET. As a result, the ratio of on-current to off-current for this MOSFET increases as the channel length is reduced, which is an important parameter for low-voltage operation. It is found that a MOSFET with channel length independent subthreshold characteristic is more suitable for low-voltage operation.

Channel length independent subthreshold characteristics in submicron MOSFETs

A novel technique for the weight redistribution after the electron-electron scattering between weighted electrons in the weighted ensemble Monte Carlo simulation is proposed. By generating an additional electron after each electron-electron collision the conservation of energy, momentum and charge is guaranteed, which has not been possible in the previously reported methods. The proposed technique has been successfully applied to an ideal gas simulation. Based on the new model, the tail carrier behavior due to the electron-electron scattering in the n/sup +/-doped silicon is studied.

A new weight redistribution technique for electron-electron scattering in the MC simulation

A new hole mobility model for hydrodynamic simulation

This paper proposes and investigates a short-channel MOSFET model down to a 0.1-/spl mu/m regime for the frequency-domain analysis of the device operation through the harmonic balance technique. The efficiency and the preciseness of our method are validated by comparison of simulation results with the two-dimensional time-domain simulation tool, MEDICI. Along with the carrier transport model, the displacement current components are included in the terminal current equations for the extended analysis under external circuit environments.

Efficient frequency-domain simulation technique for short-channel MOSFET

We propose a harmonic balance technique for the frequency-domain analysis of MOSFET operation. Our approach is based on the charge-sheet and the non-quasistatic(NQS) MOSFET models in the channel region with the harmonic balance(HB) technique applied to the channel charges. Lateral field effect is considered in the formulation to analyze the short channel MOSFET devices. It is shown that the proposed method renders a computationally efficient tool to analyze the harmonic distortion occurrence in the MOSFET devices due to the nonlinear response of the channel charges.

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Chanho Lee

Papers

Channel length independent subthreshold characteristics in submicron MOSFETs

A new weight redistribution technique for electron-electron scattering in the MC simulation

A new hole mobility model for hydrodynamic simulation

Efficient frequency-domain simulation technique for short-channel MOSFET

An Efficient Frequency-Domain Analysis Technique of MOSFET Operation