Relation Between Defect Density and Local Structures of a-Si:H

1995 ◽  
Vol 377 ◽  
Author(s):  
M. Azuma ◽  
K. Nakamura ◽  
T. Yokoi ◽  
K. Yoshino ◽  
I. Shimizu
Keyword(s):  
Local Structure ◽  
Atomic Hydrogen ◽  
Defect Density ◽  
In Situ Monitoring ◽  
High Quality ◽  
Local Structures ◽  
Chemical Annealing ◽  
Rf Glow Discharge ◽  
The Stability

ABSTRACTHigh quality a-Si:H thin films with varied optical gaps in the range from 1.55 to 2.1 eV were fabricated by various methods, i.e., the standard RF glow discharge of silane, “Chemical Annealing” and ECR-H-plasma from SiCl2H2 under in situ monitoring with an ellipsome try. Despite marked differences in the local structure, all these films showed low defect density as low as (3–5) × 1015 cm3. In addition, the stability for light soaking was improved markedly for the films made by promoting intensively structural relaxation with atomic hydrogen.

Intentional Reconstruction of Silicon Network on the Surface and within Sub-Surface by H and Ar

1997 ◽  
Vol 467 ◽  
Author(s):  
W. Futako ◽  
K. Fukutani ◽  
I. Shimizu
Keyword(s):  
Thin Films ◽  
Glow Discharge ◽  
Thin Layer ◽  
Defect Density ◽  
Hydrogen Atoms ◽  
Silicon Thin Films ◽  
Chemical Annealing ◽  
Rf Glow Discharge ◽  
Wide Gap ◽  
The Stability

ABSTRACTSilicon thin films were prepared by “Chemical Annealing” where the deposition of thin layer (<3 nm thick) by RF glow discharge of SiH4 and the treatment with hydrogen atoms (H) or triplet state of argon (3Ar) were repeated alternatating. Consequently, wide gap a-Si:H with the gap of 2.1 eV was made by H-treatmentat rather low substrate temperature (Ts<150 °C), while a-Si:H with the gap narrower than 1.6 eV was obtained by the treatment with 3Ar at high Ts (>300 °C), resulting from the release of excessive hydrogen. Both the wider or the narrower gap films exhibited low defect density lower than 1016 cm−3 and obvious improvements in the stability for light soaking.

Fabrication of Polycrystalline Silicon on Glass from Fluorinated Precursors with the Aid of Atomic Hydrogen

1995 ◽  
Vol 403 ◽  
Author(s):  
T. Akasaka ◽  
D. He ◽  
I. Shimizu
Keyword(s):  
Thin Films ◽  
Atomic Hydrogen ◽  
Polycrystalline Silicon ◽  
In Situ Observation ◽  
Layer By Layer ◽  
High Quality ◽  
Deposition Parameters ◽  
Columnar Grains ◽  
Step Growth

AbstractHigh quality polycrystalline silicon was made on glass from fluorinated precursors by two step growth, i.e., (1) formation of seed crystals on glass by layer-by-layer(LL) technique and (2) grain-growth on the seeds. In LL technique, deposition of ultra-thin films and treatment with atomic hydrogen was repeated alternately. Columnar grains with 200 nm dia were grown epitaxy-like on the seeds by optimizing the deposition parameters under in situ observation with spectroscopic ellipsometry.

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

Study on Support of Roadways in Fractured Rock Mass under Mining-Induced Stresses

2013 ◽  
Vol 807-809 ◽  
pp. 2332-2339
Author(s):  
Qiang Wang ◽  
Jin Yu Chen
Keyword(s):  
Rock Mass ◽  
Abutment Pressure ◽  
Underground Mining ◽  
Fractured Rock ◽  
The State ◽  
In Situ Monitoring ◽  
Initial Stresses ◽  
Induced Stresses ◽  
The Stability

One of the difficult issues in underground mining is the ground control of roadway subject to mining induced stresses. As a longwall face advances, the state of initial stresses dramatically changes. Accordingly, lateral abutment pressure forms on the pillar and frontal abutment pressure on the roof and lateral sides of the roadway. These pressures will lead to severe deformation and deterioration of the rock mass surrounding the entries. In this paper, a systemic study on this issue is proposed using the combination of numerical modeling and in-situ monitoring which was carried out at a coal mine in the Lu.An Group, China. The condition of stress redistribution caused by mining-induced stresses and the state of the surrounding rock mass of the roadway situated in front the work face are systematically investigated. Different patterns of support and reinforcement as well as their effects on the stability of the roadway are also presented.

Monitoring and Analysis on the Supporting Structure for Deep Foundation Pit

2014 ◽  
Vol 580-583 ◽  
pp. 787-790
Author(s):  
Hai Xia Sun ◽  
Ke Zhang ◽  
Si Li Chen
Keyword(s):  
In Situ Monitoring ◽  
Monitoring Data ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Metro Station ◽  
Deep Foundation Pit ◽  
Supporting Structure ◽  
Deformation Features ◽  
The Stability

This article mainly expounds the importance of in-situ monitoring on the construction process of deep foundation pit. Taking the deep foundation pit of some Shenyang metro station for example, the deformation features of the supporting structure and the internal and external of foundation pit is analyzed, according to the monitoring data of the fender pile displacement during the excavation of deep foundation pit. The conclusion is obtained that the timely and accurate in-situ monitoring information is necessary to guaranteeing construction safety. We should pay more attention to the excavation speed and exert the interior support timely during the excavation of foundation pit to avoid large deformation and danger. The analytical results of monitoring data shows that the whole stage of foundation pit excavation is stable and the fender pile with internal supports can guarantee the stability of foundation pit.

High Quality Ultrathin Gate Dielectrics Prepared by In-Situ RTP

1995 ◽  
Vol 387 ◽  
Author(s):  
L. K. Han ◽  
M. Bhat ◽  
J. Yan ◽  
D. Wristers ◽  
D. L. Kwong
Keyword(s):  
Gate Dielectric ◽  
Defect Density ◽  
Gate Dielectrics ◽  
Charge Trapping ◽  
Interface State ◽  
High Quality ◽  
Hot Carrier ◽  
Thermal Oxide ◽  
State Generation

AbstractThis paper reports on the formation of high quality ultrathin oxynitride gate dielectric by in-situ rapid thermal multiprocessing. Four such gate dielectrics are discussed here; (i) in-situ NO-annealed SiO2, (ii) N2O- or NO- or O2-grown bottom oxide/RTCVD SiO2/thermal oxide, (iii) N2O-grown bottom oxide/Si3N4/N2O-oxide (ONO) and (iv) N2O-grown bottom oxide/RTCVD SiO2/N2O-oxide. Results show that capacitors with NO-based oxynitride gate dielectrics, stacked oxynitride gate dielectrics with varying quality of bottom oxide (O2/N2O/NO), and the ONO structures show high endurance to interface degradation, low defect-density and high charge-to-breakdown compared to thermal oxide. The N2O-last reoxidation step used in the stacked dielectrics and ONO structures is seen to suppress charge trapping and interface state generation under Fowler-Nordheim injection. The stacked oxynitride gate dielectrics also show excellent MOSFET performance in terms of transconductance and mobility. While the current drivability and mobilities are found to be comparable to thermal oxide for N-channel MOSFET's, the hot-carrier immunity of N-channel MOSFET's with the N2O-oxide/CVD-SiO2/N2O-oxide gate dielectrics is found to be significantly enhanced over that of conventional thermal oxide.

Modulation of Growing Surface with Atomic Hydrogen and Excited Argon to Fabricate Narrow Gap a-Si:H

1996 ◽  
Vol 420 ◽  
Author(s):  
W. Futako ◽  
I. Shimizu ◽  
C. M. Fortmann
Keyword(s):  
Thin Layer ◽  
Substrate Temperature ◽  
Amorphous Silicon ◽  
Atomic Hydrogen ◽  
Hydrogenated Amorphous Silicon ◽  
High Substrate Temperature ◽  
Narrow Gap ◽  
High Quality ◽  
Chemical Annealing ◽  
Hydrogenated Amorphous

AbstractHydrogenated amorphous silicon (a-Si:H) with a gaps narrower than 1.7 eV were made by repeating the deposition of a thin layer (1–3 nm thick) and the treatment of growing surface with a mixture of H and Ar*. Crystallization induced by permeation of hydrogen into the subsurface at high substrate temperature (>200C) was efficiently prevented by treating with a mixture of H and Ar*. The activation of growing surface may arise from releasing a part of hydrogen on surface by treating with Ar*. High quality a-Si:H films containing hydrogen of 3 atom % with a gap of 1.6 eV were made by chemical annealing with a mixture of H and Ar*.

Local Structures around Zr, Ni and Cu for the Zr67Cu33 and Zr67Ni33 Metallic Glasses

2007 ◽  
Vol 539-543 ◽  
pp. 1959-1963 ◽  
Author(s):  
M. Matsuura ◽  
Masaki Sakurai ◽  
Wei Zhang ◽  
A. Inoue
Keyword(s):  
Synchrotron Radiation ◽  
Metallic Glasses ◽  
Local Structure ◽  
Liquid State ◽  
Local Structures ◽  
The Stability

XAFS measurements of the Cu, Ni and Zr K-edges for the melt-quenched Zr67Cu33 and Zr67Ni33 metallic glasses were curried out using synchrotron radiation at 20K. Fitting calculations for the EXAFS results reveal that local structure around Ni and Zr in Zr67Ni33 is well represented by those for the crystalline Zr2Ni, while local structure around Zr in Zr67Cu33 is better fitted by an icosahedron rather than crystalline Zr2Cu. Such differences of the local structure attribute to the differences of the stability of super-cooled liquid state and glass formability between Zr67Cu33 and Zr67Ni33 metallic glasses.

High Quality, Low Bandgap a-Si Films and Devices Produced Using Chemical Annealing

2010 ◽  
Vol 1245 ◽  
Author(s):  
Vikram Dalal ◽  
Ashutosh Shyam ◽  
Dan Congreve ◽  
Max Noack
Keyword(s):  
Quantum Efficiency ◽  
Defect Density ◽  
Amorphous Structure ◽  
Energy Curve ◽  
Layer By Layer ◽  
X Ray Diffraction ◽  
High Quality ◽  
Chemical Annealing ◽  
Annealing Cycle ◽  
Si Films

AbstractWe report on the growth and properties of novel amorphous Silicon (a-Si:H) p-i-n devices prepared using chemical annealing with argon gas. The i layer in the p-i-n devices was grown using a layer by layer approach, where the growth of a very thin a-Si:H layer (7-30 angstroms) grown using a silane:argon mixture was followed by chemical anneal by argon ions. Repeated cycling of such growth/anneal cycles was used to produce the desired total thickness of the i layer. The thickness of the a-Si layer, and duration of the anneal time, were varied systematically. Pressure and power of the plasma discharge were also systematically varied. It was found that a thin a-Si layer, <10 angstroms, and low pressures which led to relatively high ion flux on the surface, gave rise to a significantly smaller bandgap in the device, as indicated by a significant lateral shift in the quantum efficiency vs. photon energy curve to lower energies. The smallest Tauc gap observed was in the range of 1.62 eV. Corresponding to this smaller bandgap, the current in the solar cell increased, and the voltage decreased. The Urbach energies of the valence band tail were also measured in the device, using the quantum efficiency vs. energy curve, and found to be in the range of45 meV, indicating high quality devices. Too much ion bombardment led to an increase in Urbach energy, and an increase in defect density in the material. Raman spectra of the device i layer indicated an amorphous structure. When hydrogen was added to argon during the annealing cycle, some materials turned microcrystalline, as indicated by the Raman spectrum, and confirmed using x-ray diffraction.

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