Quasi Drift and Quasi Diffusion: A Grain size Dependent Polysilicon Tft Model

1999 ◽  
Vol 557 ◽  
Author(s):  
W. Eccleston
Keyword(s):  
Grain Size ◽  
Crystalline Silicon ◽  
Electrical Characteristics ◽  
High Current ◽  
Field Effect Mobility ◽  
Physical Processes ◽  
Potential Barriers ◽  
Size Dependent ◽  
Physically Based ◽  
Polysilicon Tft

AbstractMost of the models for Thin Film Transistors take no account of the way that electrons move across grain boundaries. The purpose of this work is to produce an analytical model, physically based, that takes account of both the change in height of the potential barriers that separate the grains, and the change of carrier density in the grains with gate voltage. The high current and subthreshold regions are treated. The model enables the change of field effect mobility with grain size and temperature to be determined. Two closed form expressions are provided which should be of value to both device and circuit designers, as well as providing insight to the physical processes occurring in such devices. They form a close analogy with the electrical characteristics of MOSFETs on crystalline silicon, diffusion and drift being replaced by quasi-diffusion and primary quasi-drift.

A Simple Physically Based Phenomenological Model for the Strengthening/Softening Behavior of Nanotwinned Copper

2015 ◽  
Vol 82 (12) ◽  
Author(s):  
X. Zhang ◽  
A. E. Romanov ◽  
E. C. Aifantis
Keyword(s):  
Grain Size ◽  
Constitutive Equation ◽  
Phenomenological Model ◽  
Temperature Effects ◽  
Atomistic Simulations ◽  
Gradient Plasticity ◽  
Size Dependent ◽  
Softening Behavior ◽  
Physically Based ◽  
Twin Thickness

A robust phenomenological model based on a modified size-dependent Voce-type constitutive equation is proposed to describe the dependence of strength on twin thickness, for nanotwinned copper (nt-Cu) polycrystals, in agreement with experiments and related atomistic simulations. A gradient plasticity argument is employed to determine the critical nanotwin thickness where the transition from Hall–Petch (HP) hardening to inverse Hall–Petch (IHP) softening occurs. Strain rate and temperature effects are also discussed. The proposed constitutive equation may be used for engineering design purposes by controlling the interplay between grain size and twin thickness.

Structural and Electrical Characterization of Shaped Beam Laser Recrystallized Polysilicon on Amorphous Substrates

1981 ◽  
Vol 4 ◽  
Author(s):  
T. J. Stultz ◽  
J. F. Gibbons
Keyword(s):  
Grain Size ◽  
Electrical Characterization ◽  
Grain Structure ◽  
Electrical Characteristics ◽  
Shaped Beam ◽  
Beam Laser ◽  
Cw Laser ◽  
Amorphous Substrates ◽  
Circular Beam

ABSTRACTStructural and electrical characterization of laser recrystallized LPCVD silicon films on amorphous substrates using a shaped cw laser beam have been performed. In comparing the results to data obtained using a circular beam, it was found that a significant increase in grain size can be achieved and that the surface morphology of the shaped beam recrystallized material was much smoother. It was also found that whereas circular beam recrystallized material has a random grain structure, shaped beam material is highly oriented with a <100> texture. Finally the electrical characteristics of the recrystallized film were very good when measured in directions parallel to the grain boundaries.

A Simulation Study for Optimizing Grain Size in Poly-Crystalline Silicon Material Using Impedance Spectroscopy

Silicon ◽  
2021 ◽  
Author(s):  
Umakanth V. ◽  
Ajit Singh ◽  
Sanjai Kumar ◽  
Neeraj Tyagi ◽  
V. K. Kaul ◽  
...  
Keyword(s):  
Grain Size ◽  
Impedance Spectroscopy ◽  
Simulation Study ◽  
Crystalline Silicon ◽  
Silicon Material

A Novel Multi-Channel Poly-Si TFT Improving Hydrogen Passivation

1997 ◽  
Vol 471 ◽  
Author(s):  
C. M. Park ◽  
J.-H. Jeon ◽  
J.-S. Yoo ◽  
M.-K. Han
Keyword(s):  
Polycrystalline Silicon ◽  
Thin Film Transistor ◽  
Gate Oxide ◽  
Electrical Characteristics ◽  
Field Effect Mobility ◽  
Silicon Thin Film ◽  
New Device ◽  
Hydrogen Radicals ◽  
Long Channel ◽  
Conventional Device

ABSTARCT:We have fabricated a new multi-channel polycrystalline silicon thin film transistor (ploy-Si TFT), of which structure may be more effectively hydrogenated than conventional multi-channel poly-Si TFT. The new multi-channel TFT has stripe-cuts in gate electrode so that more hydrogen radicals penetrate into the gate oxide and passivate the active poly-Si layer. After 90 min. hydrogenation of the new device, the electrical characteristics such as threshold voltage and field effect mobility are improved more than those of conventional device.The new multi-channel poly-Si TFT, which receives more hydrogen radicals thorough gate oxide than the conventional multi-channel TFT, can be hydrogenated effectively in long channel devices. Besides the improvement of the device characteristics, our experimental results show that the dominant hydrogenation path is the diffusion though the gate oxide.

Grain-size-dependent gas-sensing properties of TiO2 nanomaterials

2015 ◽  
Vol 211 ◽  
pp. 67-76 ◽  
Author(s):  
B. Lyson-Sypien ◽  
M. Radecka ◽  
M. Rekas ◽  
K. Swierczek ◽  
K. Michalow-Mauke ◽  
...  
Keyword(s):  
Grain Size ◽  
Gas Sensing ◽  
Sensing Properties ◽  
Size Dependent ◽  
Gas Sensing Properties ◽  
Tio2 Nanomaterials

Controlling Grain Size in Oxide Ceramics for Optimization of Strength and Wear Resistance

2012 ◽  
Vol 715-716 ◽  
pp. 703-710
Author(s):  
W.M. Rainforth ◽  
P. Zeng ◽  
L. Ma
Keyword(s):  
Grain Size ◽  
Sliding Wear ◽  
Second Phase ◽  
Alumina Ceramics ◽  
Size Dependent ◽  
Mild Wear ◽  
Accumulation Mechanism ◽  
Wear Transition ◽  
Magnitude Increase ◽  
Zirconia Toughened Alumina

t is well known that alumina ceramics undergo a time dependent wear transition during sliding wear. The transition, which is associated with 1-2 orders of magnitude increase in specific wear rate, involves a change from mild wear to intergranular fracture. The transition is strongly grain size dependent, with the time to the transition decreasing with grain size. However, there is a minimum grain size that can be achieved in fully dense alumina using commercially viable processing. Alternative strategies for reducing grain size and increasing toughness are through the addition of a fine second phase, with SiC and ZrO2being the most promising. The resultant composite not only has finer grain size, but also exhibits additional toughening mechanisms. This paper reports on the microstructural control in alumina, zirconia toughened alumina and alumina-silicon carbide composites. The grain size and residual stress distribution are related to the damage accumulation mechanism that occur during frictional contact, in particular the surface specific dislocation activity.

Analytical Treatment of Field-Effect Conduction in Polysilicon thin film Transistors

1997 ◽  
Vol 471 ◽  
Author(s):  
W. Eccleston
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Thin Film Transistors ◽  
Field Effect ◽  
Drain Current ◽  
High Current ◽  
Analytical Treatment ◽  
Channel Mobility ◽  
Current Region ◽  
The Relationship

ABSTRACTThe drift of electrons in the channels of Thin Film Transistors is analysed for discrete grains separated by grain boundaries containing amorphous silicon. The model provides the relationship channel mobility and grain size. The relationship between drain current and the terminal voltages is also predicted. The model relates to normal high current region of transistor operation.

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