Ac and Dc Characterization and Spice Modeling of Short Channel Polysilicon Tfts

1996 ◽  
Vol 424 ◽  
Author(s):  
M. D. Jacunski ◽  
M. S. Shur ◽  
T. Ytterdal ◽  
A. A. Owusu ◽  
M. Hack
Keyword(s):  
Frequency Dispersion ◽  
Channel Length ◽  
Short Channel ◽  
Spice Model ◽  
Dc Characteristics ◽  
Physically Based ◽  
In Series ◽  
Drain Bias ◽  
Long Channel ◽  
Good Agreement

AbstractWe present an analytical SPICE model for the AC and DC characteristics of n and p channel polysilicon TFTs which scales fully with channel length and width in all regimes of operation (leakage, subthreshold, above threshold, and kink) and accounts for the frequency dispersion of the capacitance. Once physically based parameters have been extracted from long channel TFTs, which include the gate length and drain bias dependencies of the device parameters, our model accurately reproduces short channel device characteristics. The AC model includes the input channel resistance in series with the gate oxide capacitance. As a result, our model is able to fit the frequency dispersion of the device capacitances. The model has been implemented in the AIM-Spice simulator and good agreement is observed between measured and modeled results for gate lengths down to 4 gim.

Early Effect for 28nm HK/MG PMOSFETs after Post Deposition Annealing Treatment

2014 ◽  
Vol 910 ◽  
pp. 40-43
Author(s):  
Win Der Lee ◽  
Mu Chun Wang
Keyword(s):  
Annealing Treatment ◽  
Channel Length ◽  
Strain Effect ◽  
Short Channel ◽  
Early Effect ◽  
Process Adjustment ◽  
High K ◽  
Long Channel ◽  
Post Deposition ◽  
Conventional Device

Exposing the Early effect (or called channel-length modulation effect) at deep subnano node high-k/metal gate (HK/MG) process is still beneficial to IC designers to reduce the obsession in design. This effect contributes the operating point in circuit concern and process adjustment. For the long channel device, the intercept under various gate voltages focuses on one point consistent with conventional device. However, the divergent phenomenon was observed at the short channel tested device due to the higher strain effect, causing the non-uniform electrical field distribution in channel.

Numerical Study of Long Channel Carbon Nanotube Based Transistors by Considering Variation in CNT Diameter

2020 ◽  
Vol 61 ◽  
pp. 78-87
Author(s):  
Sajjad Dehghani
Keyword(s):  
Carbon Nanotube ◽  
Chemical Sensors ◽  
Field Effect Transistors ◽  
Numerical Study ◽  
Electrical Current ◽  
Light Emitters ◽  
Short Channel ◽  
Numerical Studies ◽  
Long Channel ◽  
Good Agreement

While much numerical studies have been done on short channel carbon nanotube field effect transistors (CNT-FETs), there are only a few numerical reports on long channel devices. Long channel CNT-FETs have been widely used in chemical sensors and biosensors as well as light emitters. Therefore, numerical study is helpful for a better understanding of the behavior of such devices. In this paper, we numerically analyze long-channel CNT-FETs by solving the continuity and charge equations self-consistently. To increase the accuracy of simulation, filed-dependent mobility is applied to the equations. Furthermore, a method is proposed to obtain the electrical current of transistors as a function of CNT diameter. Obtained results are in good agreement with the previous experimental data. It is found that compared to a CNT-based resistor, the dependence of current on diameter is much higher in a CNT-FET. Finally, reproducibility of transistors based on the arrays of random CNTs of 1-2 nm diameter in terms of the CNTs number is also investigated.

scholarly journals Monte Carlo Calibrated Drift-Diffusion Simulation of Short Channel HFETs

VLSI Design ◽  
1998 ◽  
Vol 8 (1-4) ◽  
pp. 319-323
Author(s):  
A. Asenov ◽  
S. Babiker ◽  
S. P. Beaumont ◽  
J. R. Barker
Keyword(s):  
Monte Carlo ◽  
Mobility Model ◽  
Channel Length ◽  
Drift Diffusion ◽  
Short Channel ◽  
Velocity Overshoot ◽  
Saturation Velocity ◽  
Mc Simulation ◽  
Diffusion Simulation ◽  
Good Agreement

In this paper we present a methodology to use drift diffusion (DD) simulations in the design of short channel heterojunction FETs (HFETs) with well pronounced velocity overshoot. In the DD simulations the velocity overshoot in the channel is emulated by forcing the saturation velocity in the field dependent mobility model to values corresponding to the average velocity in the channel obtained from Monte Carlo (MC) simulation. To illustrate our approach we compare enhanced DD and MC simulation results for a pseudomorphic HEMTs with 0.12 μm channel length, which are in good agreement. The usefulness of the described methodology is illustrated in a simulation example of self aligned gamma gate pseudomorphic HEMTs. The effect of the gamma gate shape and the self aligned contacts on the overall device performance has been investigated.

Exploration of Amorphous Silicon Thin Film Transistor Degradation with Thermal Anneal

1993 ◽  
Vol 297 ◽  
Author(s):  
R.F. Kwasnick ◽  
G.E. Possin ◽  
W.L. Hill II
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Substrate Surface ◽  
Thin Film Transistor ◽  
Transfer Characteristic ◽  
Channel Length ◽  
Silicon Thin Film ◽  
Short Channel ◽  
Effective Mobility ◽  
Long Channel

We have measured the device characterisics of short and long channel inverted- staggered hydrogenated amorphous silicon thin film transistors (TFTs) with either Mo or Cr source/drain metal after annealing at temperatures from 225 C to 275 C. The TFT deposition temperature at the substrate surface was about 270 C. From the slope of the transfer characteristic an effective mobility is extracted. Devices with Mo source/drain metal exhibit an initial effective mobility increase at short times (within about 30 min), while those with Cr do not. At long times the mobility of all devices decreases. The mobility changes are greatest for short channel length devices because of contact effects. The channel length dependence of the behavior permits a separation of the device behavior into contact and intrinsic mobility components.

Contact Effects in High Mobility Microcrystalline Silicon Thin-Film Transistors

2007 ◽  
Vol 989 ◽  
Author(s):  
Kah Yoong Chan ◽  
Eerke Bunte ◽  
Helmut Stiebig ◽  
Dietmar Knipp
Keyword(s):  
Thin Film ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
High Mobility ◽  
Chemical Vapor ◽  
Channel Length ◽  
Microcrystalline Silicon ◽  
Silicon Thin Film ◽  
Short Channel ◽  
Long Channel

AbstractMicrocrystalline silicon (mc-Si:H) has recently been proven to be a promising material for thin-film transistors (TFTs). We present mc-Si:H TFTs fabricated by plasma-enhanced chemical vapor deposition at temperatures below 200°C in a condition similar to the fabrication of amorphous silicon TFTs. The mc-Si:H TFTs exhibit device mobilities exceeding 30 cm2/Vs and threshold voltages in the range of 2.5V. Such high mobilities are observed for long channel devices (50-200 mm). For short channel device (2 mm), the mobility reduces to 7 cm2/Vs. Furthermore the threshold voltage of the TFTs decreases with decreasing channel length. A simple model is developed, which explains the observed reduction of the device mobility and threshold voltage with decreasing channel length by the influence of drain and source contacts.

scholarly journals Four Level Simulation of MOSFET

1998 ◽  
Vol 21 (3) ◽  
pp. 231-257 ◽  
Author(s):  
M. N. Doja ◽  
Moinuddin ◽  
Umesh Kumar
Keyword(s):  
Channel Length ◽  
Short Channel ◽  
Mobility Degradation ◽  
Field Dependent ◽  
Degradation Models ◽  
Long Channel

In this paper a software (MOSOFT) has been developed for 4-level simulation of MOSFETS. This software simulates the device characteristics up to micron channel length and includes long channel, short channel, subthreshold and field dependent mobility degradation models.

Modeling and Investigation of SiGe Based MOSFET Structure Transport Characteristics

2007 ◽  
Vol 555 ◽  
pp. 101-106
Author(s):  
P.M. Lukić ◽  
R.M. Ramović ◽  
Rajko M. Šašić
Keyword(s):  
Electric Field ◽  
Carrier Mobility ◽  
Mobility Model ◽  
Channel Length ◽  
Operating Characteristics ◽  
Short Channel ◽  
Electric Field Effects ◽  
Vertical Electric Field ◽  
Source Resistance ◽  
Long Channel

The focus of this paper was the investigation and modeling of transport characteristics in a strained SiGe based MOSFET structure, which might be of fundamental importance for the understanding of its operating characteristics. In the investigation, carrier mobility dependence on the lateral and vertical electric field is especially considered. Carrier mobility models for long channel as well as short channel SiGe MOSFETs are also presented. Average effective electric field model is proposed taking into account impact of high electric field effects on the effective channel length. In the final effective carrier mobility model, for the short channel SiGe MOSFETs, serial drain to source resistance is included. At the same time, proposed models are relatively simple. By using the presented model, simulations were performed.

The Effect of Channel Length on the Residual Circulation in Tidally Dominated Channels

2005 ◽  
Vol 35 (10) ◽  
pp. 1826-1840 ◽  
Author(s):  
Chunyan Li ◽  
James O’Donnell
Keyword(s):  
Sea Level ◽  
Deep Water ◽  
Channel Length ◽  
Spatial Gradient ◽  
Exchange Flow ◽  
Residual Circulation ◽  
Short Channel ◽  
Mean Sea Level ◽  
The Mean ◽  
Long Channel

Abstract With an analytic model, this paper describes the subtidal circulation in tidally dominated channels of different lengths, with arbitrary lateral depth variations. The focus is on an important parameter associated with the reversal of the exchange flows. This parameter (δ) is defined as the ratio between the channel length and one-quarter of the tidal wavelength, which is determined by water depth and tidal frequency. In this study, a standard bottom drag coefficient, CD = 0.0025, is used. For a channel with δ smaller than 0.6–0.7 (short channels), the exchange flow at the open end has an inward transport in deep water and an outward transport in shallow water. This situation is just the opposite of channels with a δ value larger than 0.6–0.7 (long channels). For a channel with a δ value of about 0.35–0.5, the exchange flow at the open end reaches the maximum of a short channel. For a channel with a δ value of about 0.85–1.0, the exchange flow at the open end reaches the maximum of a long channel, with the inward flux of water occurring over the shoal area and the outward flow in the deep-water area. However, near the closed end of a long channel, the exchange flow appears as that in a short channel—that is, the exchange flow changes direction along the channel from the head to the open end of the channel. For a channel with a δ value of about 0.6–0.7, the tidally induced subtidal exchange flow at the open end reaches its minimum when there is little flow across the open end and the water residence time reaches its maximum. The mean sea level increases toward the closed end for all δ values. However, the spatial gradient of the mean sea level in a short channel is much smaller than that of a long channel. The differences between short and long channels are caused by a shift in dynamical balance of momentum or, equivalently, a change in tidal wave characteristics from a progressive wave to a standing wave.

Projected Performance of Sub-10 nm GaN-based Double Gate MOSFETs

2017 ◽  
Vol 2 (2) ◽  
pp. 15-19 ◽  
Author(s):  
Md. Saud Al Faisal ◽  
Md. Rokib Hasan ◽  
Marwan Hossain ◽  
Mohammad Saiful Islam
Keyword(s):  
High Speed ◽  
Field Effect Transistors ◽  
Cmos Technology ◽  
Channel Length ◽  
Capacitive Coupling ◽  
Oxide Semiconductor ◽  
Double Gate ◽  
Short Channel ◽  
Channel Effects ◽  
Silvaco Atlas

GaN-based double gate metal-oxide semiconductor field-effect transistors (DG-MOSFETs) in sub-10 nm regime have been designed for the next generation logic applications. To rigorously evaluate the device performance, non-equilibrium Green’s function formalism are performed using SILVACO ATLAS. The device is turn on at gate voltage, VGS =1 V while it is going to off at VGS = 0 V. The ON-state and OFF-state drain currents are found as 12 mA/μm and ~10-8 A/μm, respectively at the drain voltage, VDS = 0.75 V. The sub-threshold slope (SS) and drain induced barrier lowering (DIBL) are ~69 mV/decade and ~43 mV/V, which are very compatible with the CMOS technology. To improve the figure of merits of the proposed device, source to gate (S-G) and gate to drain (G-D) distances are varied which is mentioned as underlap. The lengths are maintained equal for both sides of the gate. The SS and DIBL are decreased with increasing the underlap length (LUN). Though the source to drain resistance is increased for enhancing the channel length, the underlap architectures exhibit better performance due to reduced capacitive coupling between the contacts (S-G and G-D) which minimize the short channel effects. Therefore, the proposed GaN-based DG-MOSFETs as one of the excellent promising candidates to substitute currently used MOSFETs for future high speed applications.

scholarly journals Impact of device scaling on the electrical properties of MoS2 field-effect transistors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Goutham Arutchelvan ◽  
Quentin Smets ◽  
Devin Verreck ◽  
Zubair Ahmed ◽  
Abhinav Gaur ◽  
...  
Keyword(s):  
Field Effect Transistors ◽  
Oxide Thickness ◽  
Channel Length ◽  
Contact Length ◽  
Power Performance ◽  
Semiconducting Materials ◽  
Large Area ◽  
Short Channel ◽  
Device Scaling ◽  
Performance Area

AbstractTwo-dimensional semiconducting materials are considered as ideal candidates for ultimate device scaling. However, a systematic study on the performance and variability impact of scaling the different device dimensions is still lacking. Here we investigate the scaling behavior across 1300 devices fabricated on large-area grown MoS2 material with channel length down to 30 nm, contact length down to 13 nm and capacitive effective oxide thickness (CET) down to 1.9 nm. These devices show best-in-class performance with transconductance of 185 μS/μm and a minimum subthreshold swing (SS) of 86 mV/dec. We find that scaling the top-contact length has no impact on the contact resistance and electrostatics of three monolayers MoS2 transistors, because edge injection is dominant. Further, we identify that SS degradation occurs at short channel length and can be mitigated by reducing the CET and lowering the Schottky barrier height. Finally, using a power performance area (PPA) analysis, we present a roadmap of material improvements to make 2D devices competitive with silicon gate-all-around devices.

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