A New Electrically Reversible Depassivation/Passivation Mechanism in Polycrystalline Silicon

1996 ◽  
Vol 424 ◽  
Author(s):  
Vyshnavi Suntharalingam ◽  
Stephen J. Fonash
Keyword(s):  
Electric Fields ◽  
Polycrystalline Silicon ◽  
Solid Phase ◽  
Hydrogen Release ◽  
Temperature Bias ◽  
Polysilicon Films ◽  
The Stability ◽  
Quartz Substrates ◽  
Hydrogenated Amorphous ◽  
Positively Charged

AbstractAn electrically reversible depassivation/passivation phenomenon, recently found for hydrogen passivated polysilicon [1] is further explored in this report. This reversible effect is seen in both ECR and RE hydrogen passivated n-channel thin film transistors (TFTs) but is not seen in the corresponding hydrogen passivated pchannel TFrs, nor is it seen in either n- or p-channel TETs before hydrogenation. This phenomenon has been observed when room temperature bias stressing TFTs fabricated on solid phase or laser crystallized polysilicon films on quartz substrates [1]. A model involving hydrogen release or capture at defects, positively charged hydrogen motion in device electric fields, and subsequent hydrogen capture at other defects has been proposed. This phenomenon has significant implications for polycrystalline silicon TFT’ design and operation. By extension, it also offers significant insight into the stability problems of hydrogenated amorphous silicon.

TEM characterization of Au/Polysilicon interactions

1990 ◽  
Vol 48 (4) ◽  
pp. 650-651
Author(s):  
N. David Theodore ◽  
Leslie H. Allen ◽  
C. Barry Carter ◽  
James W. Mayer
Keyword(s):  
Solid Phase ◽  
Single Crystal Silicon ◽  
Chemical Vapor ◽  
Electrical Contacts ◽  
Silicon Substrates ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Polysilicon Films ◽  
The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

P-channel Polycrystalline Silicon Thin Film Transistors on Steel Foil Substrates

2001 ◽  
Vol 664 ◽  
Author(s):  
Ming Wu ◽  
Sigurd Wagner
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Polycrystalline Silicon ◽  
Field Effect ◽  
Drain Current ◽  
Silicon Thin Film ◽  
Polysilicon Films ◽  
Source Voltage ◽  
Steel Substrates ◽  
Hydrogenated Amorphous

ABSTRACTWe fabricated self-aligned polycrystalline silicon (polysilicon) thin film transistors on flexible steel substrates. The polysilicon was formed by furnace crystallization of hydrogenated amorphous silicon at 950°C/20sec or 750°C/2min. The TFTs made from these polysilicon films have hole field effect mobilities in the linear regime of 22 cm2·V−1s−1 (950°C) and 14 cm2·V−1s−1 (750°C). The OFF current at 10 V drain-source voltage is 10−10A and the drain current ON/OFF ratio is ∼106.

The influence of the Stokes and Archimedes forces on the stability of a two-phase flow

2003 ◽  
Vol 3 ◽  
pp. 266-270
Author(s):  
B.H. Khudjuyerov ◽  
I.A. Chuliev
Keyword(s):  
Spectral Method ◽  
Stability Region ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Stability Characteristic ◽  
Phase Flow ◽  
Two Phase ◽  
The Stability

The problem of the stability of a two-phase flow is considered. The solution of the stability equations is performed by the spectral method using polynomials of Chebyshev. A decrease in the stability region gas flow with the addition of particles of the solid phase. The analysis influence on the stability characteristic of Stokes and Archimedes forces.

Electrohydrodynamic stability: Taylor–Melcher theory for a liquid bridge suspended in a dielectric gas

2002 ◽  
Vol 452 ◽  
pp. 163-187 ◽  
Author(s):  
C. L. BURCHAM ◽  
D. A. SAVILLE
Keyword(s):  
Surface Tension ◽  
Dielectric Constant ◽  
Electric Fields ◽  
Liquid Bridge ◽  
Numerical Solutions ◽  
Specific Conductivity ◽  
Axisymmetric Deformation ◽  
Aspect Ratios ◽  
The Stability ◽  
Theory And Experiment

A liquid bridge is a column of liquid, pinned at each end. Here we analyse the stability of a bridge pinned between planar electrodes held at different potentials and surrounded by a non-conducting, dielectric gas. In the absence of electric fields, surface tension destabilizes bridges with aspect ratios (length/diameter) greater than π. Here we describe how electrical forces counteract surface tension, using a linearized model. When the liquid is treated as an Ohmic conductor, the specific conductivity level is irrelevant and only the dielectric properties of the bridge and the surrounding gas are involved. Fourier series and a biharmonic, biorthogonal set of Papkovich–Fadle functions are used to formulate an eigenvalue problem. Numerical solutions disclose that the most unstable axisymmetric deformation is antisymmetric with respect to the bridge’s midplane. It is shown that whilst a bridge whose length exceeds its circumference may be unstable, a sufficiently strong axial field provides stability if the dielectric constant of the bridge exceeds that of the surrounding fluid. Conversely, a field destabilizes a bridge whose dielectric constant is lower than that of its surroundings, even when its aspect ratio is less than π. Bridge behaviour is sensitive to the presence of conduction along the surface and much higher fields are required for stability when surface transport is present. The theoretical results are compared with experimental work (Burcham & Saville 2000) that demonstrated how a field stabilizes an otherwise unstable configuration. According to the experiments, the bridge undergoes two asymmetric transitions (cylinder-to-amphora and pinch-off) as the field is reduced. Agreement between theory and experiment for the field strength at the pinch-off transition is excellent, but less so for the change from cylinder to amphora. Using surface conductivity as an adjustable parameter brings theory and experiment into agreement.

Light-Induced Metastable Defects in a-Si:H: Towards an Understanding

1985 ◽  
Vol 49 ◽  
Author(s):  
Martin Stutzmann ◽  
Warren B. Jackson ◽  
Chuang Chuang Tsai
Keyword(s):  
Amorphous Silicon ◽  
Mechanical Stress ◽  
Hydrogenated Amorphous Silicon ◽  
Material Parameters ◽  
Kinetic Behaviour ◽  
Proposed Model ◽  
Special Cases ◽  
The Stability ◽  
Hydrogenated Amorphous

AbstractThe dependence of the creation and the annealing of metastable dangling bonds in hydrogenated amorphous silicon on various material parameters will be discussed in the context of a recently proposed model. After a brief review of the kinetic behaviour governing defect creation and annealing in undoped a- Si:H, a number of special cases will be analyzed: the influence of alloying with O, N, C, and Ge, changes introduced by doping and compensation, and the role of mechanical stress. Finally, possibilities to increase the stability of a-Si:H based devices will be examined.

Comparison of Pulsed Laser and Furnace Annealing of Nitrogen Implanted Silicon

1983 ◽  
Vol 23 ◽  
Author(s):  
T. P. Smith ◽  
P. J. Stiles ◽  
W. M. Augustyniak ◽  
W. L. Brown ◽  
D. C. Jacobson ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Polycrystalline Silicon ◽  
Laser Annealing ◽  
Semiconductor Device ◽  
Solid Phase ◽  
Pulsed Laser ◽  
Nitride Layer ◽  
High Dose ◽  
Infrared Transmission ◽  
Furnace Annealing

ABSTRACTFormation of buried insulating layers and redistribution of impurities during annealing are important processes in new semiconductor device technologies. We have studied pulsed ruby laser and furnace annealing of high dose (D>1017 N/cm2) 50 KeV nitrogen implanted silicon. Using He Back scattering and channeling, X-ray diffraction, transmission electron microscopy, and infrared transmission spectroscopy, we have compared liquid and solid phase regrowth, diffusion, impurity segregation and nitride formation. As has been previously reported, during furnace annealing at or above 1200C nitrogen redistributes and forms a polycrystalline silicon nitride (Si3N4 ) layer. [1–4] In contrast, pulsed laser annealing produces a buried amorphous silicon nitride layer filled with voids or bubbles below a layer of polycrystalline silicon.

The Effect of Temperature and Pressure on Residual Stress in LPCVD Polysilicon Films

1992 ◽  
Vol 276 ◽  
Author(s):  
D-G. Oei ◽  
S. L. McCarthy
Keyword(s):  
Residual Stress ◽  
Deposition Temperature ◽  
Polycrystalline Silicon ◽  
Chemical Vapor ◽  
Effect Of Temperature ◽  
Pressure Chemical ◽  
Polysilicon Films ◽  
Oriented Polycrystalline ◽  
Temperature And Pressure ◽  
Reduced Pressures

ABSTRACTMeasurements of the residual stress in polysilicon films made by Low Pressure Chemical Vapor Deposition (LPCVD) at different deposition pressures and temperatures are reported. The stress behavior of phosphorus (P)-ion implanted/annealed polysilicon films is also reported. Within the temperature range of deposition, 580 °C to 650 °C, the stress vs deposition temperature plot exhibits a transition region in which the stress of the film changes from highly compressive to highly tensile and back to highly compressive as the deposition temperature increases. This behavior was observed in films that were made by the LPCVD process at reduced pressures of 210 and 320 mTORR. At deposition temperatures below 590 °C the deposit is predominantly amorphous, and the film is highly compressive; at temperatures above 610 °C (110) oriented polycrystalline silicon is formed exhibiting high compressive residual stress.

Comparison of Structural and Electrical Characteristics of Solid-Phase Epitaxial Films Recrystallized By Rapid Thermal Annealing and Furnace Annealing

1985 ◽  
Vol 53 ◽  
Author(s):  
R. Sundaresan ◽  
P.-H. Chang ◽  
S.D.S. Malhi ◽  
H.W. Lam
Keyword(s):  
Solid Phase ◽  
Epitaxial Films ◽  
Electrical Characteristics ◽  
Lateral Extension ◽  
Rapid Thermal Anneal ◽  
Furnace Annealing ◽  
Layer 4 ◽  
Polysilicon Films ◽  
Average Electron ◽  
Temperature Furnace

ABSTRACTSolid-phase epitaxial regrowth of polysilicon films. amorphized by a room-temperature silicon implant. has been achieved using a (low temperature) furnace anneal or a (high temperature) rapid thermal anneal. Lateral extension of the growth onto an oxide layer, 4 μm wide, has also been observed. The electrical properties of the films were examined by building MO2S devices in them. Average electron mobilities of 520 cm2/v-sec and 200 cm2/v-sec have been measured for films regrown on top of silicon and oxide respectively.

First Principles Investigation of the Stability and the Chemical Behavior of Hydrogen in ThCoH4

2011 ◽  
Vol 66 (3) ◽  
pp. 269-274
Author(s):  
Samir F. Matar
Keyword(s):  
Negative Charge ◽  
Geometry Optimization ◽  
Full Geometry Optimization ◽  
Intermetallic Matrix ◽  
Charge Analysis ◽  
The Stability ◽  
The One ◽  
Site Selective ◽  
Bader Charge Analysis ◽  
Positively Charged

We address the changes in the electronic structure brought by the insertion of hydrogen into ThCo leading to the experimentally observed ThCoH4. Full geometry optimization positions the hydrogen in three sites stabilized in the expanded intermetallic matrix. From a Bader charge analysis, hydrogen is found to be in a narrow iono-covalent (~−0.6) to covalent (~−0.3) bonding which should enable site-selective desorption. The overall chemical picture shows a positively charged Thδ+ with the negative charge redistributed over a complex anion {CoH4}δ− with δ~1.8. Nevertheless this charge transfer remains far from the one in the more ionic hydridocobaltate anion CoH54− in Mg2CoH5, due to the largely electropositive character of Mg.

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