Correlation Between Freeze-In Temperature of Defect Density and Hydrogen Concentration in a-Si:H

1991 ◽  
Vol 219 ◽  
Author(s):  
X. Xu ◽  
M. Isomura ◽  
J. H. Yoon ◽  
S. Wagner ◽  
J. R. Abelson
Keyword(s):  
Hydrogen Concentration ◽  
Defect Density ◽  
Dangling Bond ◽  
Bond Density ◽  
Higher Temperature ◽  
Defect Densities

ABSTRACTWe measured the freeze-in temperature of the dangling-bond density in a-Si:H in nine samples with hydrogen concentrations ranging from 7.0 to 31 at.%. The measurements were made by determining the defect density of samples quenched from successively higher temperature. We determined the defect densities with the constant photoconductivity method. The freeze-in temperature is 211±10 °C, and is independent of hydrogen concentration.

Simultaneous Relaxation of Network and Defects in Silicon-Implanted a-Si:H

1995 ◽  
Vol 377 ◽  
Author(s):  
J. Nakata ◽  
S. Sherman ◽  
S. Wagner ◽  
P. A. Stolk ◽  
J. M. Poate
Keyword(s):  
Electronic Transport ◽  
Annealing Temperature ◽  
Urbach Energy ◽  
Defect Density ◽  
Dark Conductivity ◽  
Equilibrium Theory ◽  
Hopping Conduction ◽  
Dangling Bond ◽  
Bond Density ◽  
Additional Illumination

ABSTRACTWe report extensive optical and electronic transport data on silicon-implanted a-Si:H, annealed in steps in the dark or with additional illumination. All measured properties relax gradually with increasing annealing temperature. The dark conductivity of the as-implanted film is dominated by hopping conduction via midgap defects. This channel is pinched off during the initial stages of annealing. The midgap defect density and the Urbach energy follow an annealing path that agrees qualitatively with the trajectory postulated by the equilibrium theory of the dangling-bond density. Therefore, the silicon network and the defect density equilibrate continuously during network relaxation.

Formation of stacking-fault tetrahedra in low defect density oxygen-implanted silicon-on-insulator material

1992 ◽  
Vol 50 (2) ◽  
pp. 1402-1403
Author(s):  
June-Dong Lee ◽  
Stephen Krause ◽  
Peter Roitman
Keyword(s):  
Integrated Circuits ◽  
Defect Density ◽  
Silicon Layer ◽  
Stacking Fault ◽  
Silicon On Insulator ◽  
Threading Dislocations ◽  
Annealing Conditions ◽  
Stacking Fault Tetrahedra ◽  
Higher Temperature ◽  
Defect Densities

Fabrication of integrated circuits on SOI (Silicon-On-Insulator) material is very attractive because it offers high component density, immunity to latch-up and radiation hardness. Among various SOI techniques SIMOX Separation by IMplantation of OXygen) provides the best material, with carrier mobilities and defect densities approaching bulk silicon values, Early SIMOX wafers were implanted at temperatures below 600°C and annealed at high temperature (>1300°C), which gave a high defect density (109cm−2), including threading dislocations and narrow stacking faults (SFs), as shown in Figure 1. Higher temperature (>600°C) implantation of SIMOX reduced defect densities to 106cm-2 with pairs of narrow SFs in the top silicon layer, as shown in Figure 2. This paper describes a further reduction of defect density in SIMOX material through various annealing conditions, which has resulted in a defect density less than 105cm−2. A new formation mechanism for stacking fault tetrahedra is also discussed.Silicon (100) wafers were sequentially implanted (620°C) and annealed (at 1320°C for 5 hours) to doses of 0.5, 0.5, and 0.8×l018cm-2.

scholarly journals Material Parameters in a Thick Hydrogenated Amorphous Silicon Detector and their Effect on Signal Collection

1989 ◽  
Vol 149 ◽  
Author(s):  
S. Qureshi ◽  
V. Perez-Mendez ◽  
S. N. Kaplan ◽  
I. Fujieda ◽  
G. Cho
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Detector ◽  
Dangling Bond ◽  
Material Parameters ◽  
Bond Density ◽  
Transient Photoconductivity ◽  
Signal Collection ◽  
Hydrogenated Amorphous

ABSTRACTTransient photoconductivity and ESR measurements were done to relate the ionized dangling bond density and the spin density of thick hydrogenated amorphous silicon (a-Si:H) detectors. We found that only a fraction (∼30–35%) of the total defect density as measured by ESR is ionized when the detector is biased into deep depletion. The measurements on annealed samples also show that this fraction is about 0.3. An explanation based on the shift of the Fermi energy is given. The measurements show that the time dependence of relaxation is a stretched exponential.

Reduction of Neutral Dangling Bond Density by Light Soaking in Nanocrystalline Silicon

1998 ◽  
Vol 507 ◽  
Author(s):  
Takahiro Matsumoto ◽  
Yasuaki Masumoto ◽  
Michio Kondo
Keyword(s):  
Electron Spin Resonance ◽  
Defect Density ◽  
Light Exposure ◽  
Reduction Rate ◽  
Nanocrystalline Silicon ◽  
Dangling Bond ◽  
Bond Density ◽  
Spin Resonance ◽  
Neutral Defect ◽  
Nanocrystalline Si

ABSTRACTThe effects of light exposure on neutral defect density at the surface of nanocrystalline Si are investigated by electron-spin resonance (ESR) experiments. A decrease of the neutral dangling bond density by light soaking was observed in this nanostructure. The reduction rate of ESR signal intensity becomes large with increasing light exposure intensity, and the reduction occurs from the excitation energy higher than 2 eV in vacuum. The reduction of the defect density can be explained in terms of the conversion of neutral states to charged states by carrier trapping.

CORRELATION BETWEEN OPTICAL DEFECT DENSITY AND SPIN DENSITY IN AMORPHOUS SILICON CARBIDE

1991 ◽  
Vol 05 (04) ◽  
pp. 285-292 ◽  
Author(s):  
F. DEMICHELIS ◽  
C.F. PIRRI ◽  
E. TRESSO
Keyword(s):  
Silicon Carbide ◽  
Absorption Coefficient ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Dangling Bond ◽  
Amorphous Silicon Carbide ◽  
Bond Density ◽  
Spin Resonance ◽  
Excess Absorption ◽  
Deposition Conditions

Amorphous silicon carbide (a-SiC:H) films deposited by different techniques under different deposition conditions have been submitted to photo-thermal deflection and photoacoustic spectroscopy (PDS and PAS) and electron spin resonance (ESR) measurements in order to obtain, through the trend of low energy absorption coefficient and the density of spins, information on the nature, energy and number of defects. The results obtained from the two techniques are often in disagreement since the dangling bond density generally does not scale with the integrated defect density. In order to explain the discrepancy the absorption coefficient has been calculated, following the Tauc model, in the three regions of fundamental absorption, Urbach tail and excess absorption. An expression for the density of defects has been obtained which depends on the integrated excess absorption coefficient through a proportionality factor.

The Effect of Post-Deuteration on Metastability in a-Si:H

1993 ◽  
Vol 297 ◽  
Author(s):  
N.H. Nickel ◽  
W.B. Jackson ◽  
C.C. Tsai
Keyword(s):  
Defect Formation ◽  
Chemical Potential ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Dangling Bond ◽  
Deuterium Plasma ◽  
Bond Density ◽  
Intense Light ◽  
Hydrogenated Amorphous ◽  
Metastable Defect

Hydrogenated amorphous silicon films were deuterated through a sequence of 1h exposures to a remote deuterium plasma at 350°C. The concentration profiles of hydrogen and deuterium were determined by SIMS at various times during the exposure sequence. The defect density in state A, after deuteration and after illumination with white light were determined using CPM measurements following each 1h exposure sequence. We find that post-deuteration does not alter the defect density in state A, change the Urbach edge, nor significantly alter metastable defect formation. Intense light soaking increases the defect density by about 5 × 10l6cm−3 independent of the total H + D concentration. These results suggest that D always enters the sample in pairs pinning the hydrogen chemical potential which supports the idea of a negative U system for hydrogen and deuterium. Despite an increase of Si-H bonds by as much as 3 × 1021cm−3, the annealed dangling bond density and the weak Si-Si bond density did not change.This suggests that the density of weak Si-Si bonds as well as the dangling bond density is determined by equilibration with strong Si-Si bonds through the interchange of H. The implications of these results for H bonding will be discussed.

New experiments on the relationship between light-induced defects and photoconductivity degradation

2001 ◽  
Vol 664 ◽  
Author(s):  
Stephan Heck ◽  
Howard M. Branz
Keyword(s):  
Activation Energy ◽  
Defect Density ◽  
Activation Energies ◽  
Dangling Bond ◽  
Fast Recovery ◽  
Slow Recovery ◽  
Degradation Model ◽  
Induced Defects ◽  
The Relationship ◽  
Hydrogenated Amorphous

ABSTRACTWe report experimental results that help settle apparent inconsistencies in earlier work on photoconductivity and light-induced defects in hydrogenated amorphous silicon (a-Si:H) and point toward a new understanding of this subject. After observing that light-induced photoconductivity degradation anneals out at much lower T than the light-induced increase in deep defect density, Han and Fritzsche[1] suggested that two kinds of defects are created during illumination of a-Si:H. In this view, one kind of defect degrades the photoconductivity and the other increases defect sub-bandgap optical absorption. However, the light-induced degradation model of Stutzmann et al.[2] assumes that photoconductivity is inversely proportional to the dangling-bond defect density. We observe two kinds of defects that are distinguished by their annealing activation energies, but because their densities remain in strict linear proportion during their creation, the two kinds of defects cannot be completely independent.In our measurements of photoconductivity and defect absorption (constant photocurrent method) during 25°C light soaking and during a series of isochronal anneals between 25 < T < 190°C, we find that the absorption measured with E ≤1.1 eV, first increases during annealing, then exhibits the usual absorption decrease found for deeper defects. The maximum in this absorption at E ≤1.1eV occurs simultaneously with a transition from fast to slow recovery of photoconductivity. The absorption for E ≤1.1eV shows two distinct annealing activation energies: the signal rises with about 0.87 eV and falls with about 1.15 eV. The 0.87 eV activation energy roughly equals the activation energy for the dominant, fast, recovery of photoconductivity. The 1.15 eV activation energy roughly equals the single activation energy for annealing of the light-induced dangling bond absorption.

The Role of Charged Defects In Current Transport Through Hydrogenated Amorphous Silicon Alloys

1998 ◽  
Vol 507 ◽  
Author(s):  
S.P. Lau ◽  
J.M. Shannon ◽  
B.J. Sealy ◽  
J.M. Marshall
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Current Transport ◽  
Dangling Bond ◽  
Silicon Alloys ◽  
Metal Structures ◽  
Bond State ◽  
Donor States ◽  
Charged Defects

ABSTRACTCurrent transport in metal-semiconductor-metal structures based on amorphous silicon alloys has been studied in relation to the density of dangling bond state defects. The density of defects was changed by varying alloy composition or by current stressing. We show that the change of current-voltage characteristics and activation energy with defect density and the onset of Poole-Frenkel conduction with composition require charged defects. It is found that there are more charged defects in amorphous silicon nitride (a-Si1−xNx:H) than in amorphous silicon carbide (a-Si1−xCx:H). In addition, an excess of negatively charged dangling bond defects compared to positively charged dangling bond defects is observed in a-Si1−xNx:H films. This is attributed to the presence of N4+ act as the donor states in silicon nitride. We find that the density of charged dangling bond defects can be higher than 1019cm−3.

Growth and Characterization of 2″ 6H-Silicon Carbide

1999 ◽  
Vol 572 ◽  
Author(s):  
Erwin Schmitt ◽  
Robert Eckstein ◽  
Martin Kölbl ◽  
Amd-Dietrich Weber
Keyword(s):  
Silicon Carbide ◽  
Boundary Conditions ◽  
Growth Process ◽  
Defect Density ◽  
Crystal Quality ◽  
Process Conditions ◽  
Thermal Boundary Conditions ◽  
Sublimation Growth ◽  
Defect Densities

ABSTRACTFor the growth of 2″ 6H-SiC a sublimation growth process was developed. By different means of characterization crystal quality was evaluated. Higher defect densities, mainly in the periphery of the crystals were found to be correlated to unfavourable process conditions. Improvement of thermal boundary conditions lead to a decreased defect density and better homogeneity over the wafer area.

Investigation of the Defect Size and Density in Thin SiON Filmfor Organic Device Encapsulation

2016 ◽  
Vol 2016 (1) ◽  
pp. 000272-000276
Author(s):  
Kunmo Chu ◽  
Ki Deok Bae ◽  
Byong Gwon Song ◽  
Yong Young Park ◽  
Jaekwan Kim ◽  
...  
Keyword(s):  
Defect Density ◽  
Chemical Vapor ◽  
Defect Size ◽  
Intrinsic Defect ◽  
Ni Substrate ◽  
Defect Site ◽  
Defect Sites ◽  
Chemical Vapor Deposited ◽  
Density Values ◽  
Defect Densities

Abstract In this study, thin SiON was grown by plasma enhanced chemical vapor deposited (PECVD) method as a thin-film encapsulation (TFE) layer. For defect visualization, electroplating results in a Cu bump grown at each defect site in the SiON film where electrolytic solution establishes contact with the Ni substrate. It was inferred that the Cu bump density could be representative of the intrinsic defect densities for the SiON film. The defect density values were obtained by monitoring the Cu bumps grown at defect sites in the SiON films and then evaluating the number of densities of the Cu bumps for the corresponding defect densities.At the same time, by analyzing the cross section of the Cu bumps grown on SiON film, a linear relation between the Cu bump diameter and the defect size increase was obtained. We expect that this electroplating method allows for rapid visualization of defect distribution and quality evaluation of TFE layers.

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