Temperature Dependence of the Growth and Saturation of Light-Induced Defects in a-Si:H

1991 ◽  
Vol 219 ◽  
Author(s):  
M. Isomura ◽  
N. Hata ◽  
S. Wagner
Keyword(s):  
Defect Density ◽  
Annealing Process ◽  
Intensity Dependence ◽  
Optical Generation ◽  
Defect Sites ◽  
Pool Model ◽  
Ion Laser ◽  
Increasing Temperature ◽  
Induced Defects ◽  
Optical Generation Rate

ABSTRACTWe report new experimental data on the light-soaking of a-Si:H with a Kr-ion laser at an optical generation rate G of at least 4×1021 to 3×1022 cm-3s1. We studied the temperature and intensity dependence of the saturation of the defect density and found that the saturation value of light-induced defects (Nsat) is insensitive to temperature and light intensity below about 90°C. Above 90°C Nsat drops with increasing temperature. This behavior can be explained within the defect pool model by a limited number of defect sites coupled with an annealing process.

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.

Comparison of Current and Light Induced Defects in a-Si:H

1993 ◽  
Vol 297 ◽  
Author(s):  
R.A. Street ◽  
W.B. Jackson ◽  
M. Hack
Keyword(s):  
Numerical Modelling ◽  
Reverse Bias ◽  
Defect Density ◽  
Reverse Current ◽  
Bias Current ◽  
Spatial Profile ◽  
Forward Current ◽  
Defect Creation ◽  
Induced Defects ◽  
Metastable Defect

Metastable defect creation by illumination and by a forward current in p-i-n devices are compared using CPM and reverse current measurements of the defect density. The data show that the same defects are formed by the two mechanisms, but with different spatial profiles. Numerical modelling shows how the spatial profile influences the reverse bias current.

scholarly journals Study on Annealing Process of Aluminum Oxide Passivation Layer for PERC Solar Cells

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1052
Author(s):  
Yu-Chun Huang ◽  
Ricky Wenkuei Chuang
Keyword(s):  
Carrier Lifetime ◽  
Defect Density ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Minority Carrier Lifetime ◽  
Atomic Layer ◽  
Film Structure ◽  
Open Circuit ◽  
Annealing Process ◽  
Surface Recombination Velocity

In this study, Atomic Layer Deposition (ALD) equipment was used to deposit Al2O3 film on a p-type silicon wafer, trimethylaluminum (TMA) and H2O were used as precursor materials, and then the post-annealing process was conducted under atmospheric pressure. The Al2O3 films annealed at different temperatures between 200–500 °C were compared to ascertain the effect of passivation films and to confirm the changes in film structure and thickness before and after annealing through TEM images. Furthermore, the negative fixed charge and interface defect density were analyzed using the C-V measurement method. Photo-induced carrier generation was used to measure the effective minority carrier lifetime, the implied open-circuit voltage, and the effective surface recombination velocity of the film. The carrier lifetime was found to be the longest (2181.7 μs) for Al2O3/Si post-annealed at 400 °C. Finally, with the use of VHF (40.68 MHz) plasma-enhanced chemical vapor deposition (PECVD) equipment, a silicon nitride (SiNx) film was plated as an anti-reflection layer over the front side of the wafer and as a capping layer on the back to realize a passivated emitter and rear contact (PERC) solar cell with optimal efficiency up to 21.54%.

Formation of Thermally Induced Defects in Silica Optical Material

2013 ◽  
Vol 853 ◽  
pp. 62-67
Author(s):  
Zhong Yin Xiao ◽  
Jian Xiang Wen ◽  
Wen Yun Luo ◽  
Wen Kai Wu ◽  
Ren Xiang Gong ◽  
...  
Keyword(s):  
High Temperature ◽  
Formation Process ◽  
Thermal History ◽  
Defect Formation ◽  
Annealing Process ◽  
Optical Material ◽  
Thermally Induced ◽  
Silica Material ◽  
Heating Treatment ◽  
Induced Defects

Characteristics of silica optical material largely depend on its thermal history. In this paper, formation of thermally induced defects in silica optical material is studied. The formation process of defect is analyzed in detail. The results show that there is an obvious difference in defect formation induced by heating treatment when the composition of silica optical material changes. Defect formation mainly displays as the produce process when the initial defects of the silica material are zero. However, defect formation expresses as the produce and annealing process when the initial defects of the silica material are not zero. The initial defect concentration can be decreased significantly when the silica material is heated in high temperature. At the same time, the new defect is also produced. These theoretic results are consistent with the previous experimental ones.

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.

Analysis and Suppression of Process-Induced Defects in Memory Devices.

2000 ◽  
Vol 610 ◽  
Author(s):  
R. Annunziata ◽  
R. Bottini ◽  
P. Colpani ◽  
C. Cremonesi ◽  
G. Ghidini ◽  
...  
Keyword(s):  
Point Defect ◽  
Defect Density ◽  
Amorphous Layer ◽  
High Dose ◽  
Thermal Treatments ◽  
Memory Devices ◽  
Layer Width ◽  
Implantation Energy ◽  
Induced Defects ◽  
The Impact

AbstractIn this paper we show that dopant decoration of process-induced defects is responsible for a failure mechanism of memory devices. From the electrical point-of-view, the defect-related failure consists in a source-to-drain resistive path formed by junction piping. This mechanism is made active by the very close spacing which is typical of present device structures. A device-like test structure is used for defect detection. This structure proves to be a very effective tool for studying the impact of various process steps on defect generation, in that it allowes statistical data about the formation of these defects to be collected. TEM analyses are extensively used for studying the evolution of end-of-range defects during subsequent thermal treatments and for measuring the amorphous layer width under various implantation conditions.The role of high dose implantations in the generation of this sort of defects is discussed. Even if the amorphous layer is completely recovered by a suitable recristallization annealing, residual defects grow and become dopant-decorated during post-implantation thermal treatments. Defect density is increased by oxidizing treatments. In this case point defect injection is active both in enhancing dopant diffusion and in growing defects.Defect formation is suppressed if the amorphous layer is made very shallow (≤ 50 nm) by suitable choices of the screen oxide and of the implantation energy. A binary collision code is used in order to estimate the dependence on energy of the self-interstitial excess outside the amorphous region. The results of these calculations indicate that defect suppression can be tentatively explained by point defect annihilation at the silicon surface.

Saturation behavior of the Light-Induced Defect Density in Hydrogenated Amorphous Silicon

1990 ◽  
Vol 192 ◽  
Author(s):  
H. R. Park ◽  
J. Z. Liu ◽  
P. Roca i Cabarrocas ◽  
A. Maruyama ◽  
M. Isomura ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Room Temperature ◽  
Urbach Energy ◽  
Defect Density ◽  
Generation Rate ◽  
Carrier Generation ◽  
Defect Generation ◽  
Ion Laser ◽  
Hydrogenated Amorphous ◽  
Defect Densities

ABSTRACTUsing a Kr ion laser (λ = 647.1 nm) to produce a carrier generation rate G of 3 × 1020 cm−3s−1, we have saturated the light-induced defect generation in hydrogenated (and fluorinated) amorphous silicon (a-Si:H(F)), within a few hours near room temperature. While the defect generation rate scales roughly with 1/G2, the saturation defect densities Ns,sat are essentially independent of G. The saturation is not due to thermal annealing. We have further measured Ns,sat m 37 a-Si:H(F) films grown in six different reactors under different conditions. The results show that Ns,sat lies between 5 × 1016 and 2 × 1017 cm−3, that Ns,sat drops with decreasing optical gap and hydrogen content, and that Ns,sat is not correlated with the initial defect density or with the Urbach energy.

A novel porous substrate for the growth of high quality GaN crystals by HVPE

RSC Advances ◽  
2014 ◽  
Vol 4 (66) ◽  
pp. 35106-35111 ◽  
Author(s):  
Yuanbin Dai ◽  
Yongzhong Wu ◽  
Lei Zhang ◽  
Yongliang Shao ◽  
Yuan Tian ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Defect Density ◽  
Annealing Process ◽  
High Temperature Annealing ◽  
Porous Substrate ◽  
High Quality

This manuscript describes a high temperature annealing process to prepare a porous substrate. The substrate was used for the growth of GaN by using HVPE method to provide reduced residual stress and low defect density.

Leveling Coatings for Reducing Atomic Oxygen Defect Density in Graphite Fiber-Epoxy Composites

1994 ◽  
Vol 37 (3) ◽  
pp. 26-31
Author(s):  
D. Jaworske ◽  
K. de Groh ◽  
G. Podojil ◽  
T. McCollum ◽  
J. Anzic
Keyword(s):  
Atomic Oxygen ◽  
Defect Density ◽  
Protective Coatings ◽  
Protective Layer ◽  
Oxide Coating ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Protective Oxide ◽  
Low Viscosity ◽  
Defect Sites

Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low-Earth orbit to reach underlying material. Onc concept for enhancing the lifetime of materials in low-Earth orbit is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface-tension-leveling coating concept, a low-viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 Å of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/cm2 were reduced to about 1000 defects/cm2 as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/cm2.

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