Photocreated Defects and Light-Induced ESR in a-Si:H and Related Alloy Films

1996 ◽  
Vol 420 ◽  
Author(s):  
Tatsuo Shimizu ◽  
Rudolf Durny ◽  
Minoru Kumeda
Keyword(s):  
Dangling Bond ◽  
Dangling Bonds ◽  
Alloy Films ◽  
New Model

AbstractTwo major problems in the field of a-Si:H and related alloy films such as a-Sil-xNx:H are addressed in this contribution, namely, the photocreation of neutral Si dangling bonds and the origin of the components of the light-induced ESR (LESR). We have proposed a new model for the photocreation of neutral Si dangling bonds in a-Si:H based on the presence of floating bonds. The model can explain the metastabilization of the broken weak bonds without the movement of H atoms. The broad, the narrow, and the dangling bond components of the LESR signal have been attributed to holes captured at negatively charged floating bonds, electrons trapped at antibonding states of weak bonds and photoexcited carriers captured at charged dangling bonds, respectively.

Wandering Dangling Bond Model for Staebler-Wronski Effects

1998 ◽  
Vol 507 ◽  
Author(s):  
Masatoshi Ikeda ◽  
Akio Kitagawa ◽  
Masakuni Suzuki
Keyword(s):  
Rate Equations ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Covalent Bonds ◽  
New Model ◽  
Bond Model ◽  
Annealing Effects

ABSTRACTA new model for Staebler-Wronski effects is proposed. Defect pairs of (D°:D+) or (D°:D°) as a precursor of neutral dangling bonds are produced by electron-phonon interactions. Most of the defect-pairs immediately rebond after creation, but some of them separate resulting in wandering dangling bonds. The separation and the wandering take place through bond-switching. When wandering dangling bonds collide, most of them make covalent bonds via defect-pairs. The rate equations based on these processes are given and annealing effects on photo-generated dangling bonds are studied.

Mechanisms for Metastability in Hydrogenated Amorphous Silicon

2000 ◽  
Vol 609 ◽  
Author(s):  
R. Biswas ◽  
Y.-P. Li ◽  
B.C. Pan
Keyword(s):  
Amorphous Silicon ◽  
Structural Changes ◽  
Defect Formation ◽  
Hydrogenated Amorphous Silicon ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
New Model ◽  
Gap States ◽  
Hydrogenated Amorphous ◽  
Metastable Defect

ABSTRACTWe propose metastabilities in amorphous silicon fall into two classes. One class is the local changes of structure affecting a macroscopic fraction of sites. The other class is the metastable generation of dangling bonds with mid-gap states. The local metastability is explained by a new metastable state formed when H is flipped to the backside of the Si-H bond at monohydride sites. The dipole moment of this H-flip defect is larger and increases the infrared absorption. This H-flip defect accounts for large structural changes observed on light soaking including larger absorption and volume dilation. We propose a new model for the generation of metastable dangling bonds. The new ‘silicon network rebonding model’ involves breaking of weak silicon bonds and formation of isolated dangling bonds, through rebonding of the silicon network. Hydrogen motion is not involved in metastable defect formation. Defect formation proceeds by breaking weak silicon bonds and formation of dangling bond-floating bond pairs. The floating bonds migrate through the network and annihilate, producing isolated dangling bonds. This new model provides a new platform for understanding the atomistic origins of lightinduced degradation.

Sensitization of the Holes Lifetime by the Addition of Dangling Bonds in a-Si:H

2001 ◽  
Vol 664 ◽  
Author(s):  
L.F. Fonseca ◽  
S. Z. Weisz ◽  
I. Balberg
Keyword(s):  
Valence Band ◽  
Important Implication ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Defect States ◽  
Band Tail ◽  
Present Understanding

ABSTRACTThis paper is concerned with the phenomenon of the increase of the holes lifetime with the increase of the dangling bond concentration in a-Si:H. This rather surprising phenomenon that was observed, but not discussed, previously is shown to be a non-trivial effect which is based on the charged nature of the dangling bonds and a special scenario of the concentrations of the various defect states in the material. The most important implication of our study is that the charged dangling bonds can sensitize the valence band tail states, in contrast with the accepted roles of these types of states. The present understanding suggests that many new interesting phototransport phenomena can be found in a-Si:H.

Dangling-Bond Relaxation and Metastability in P-Type Hydrogenated Amorphous Silicon

1995 ◽  
Vol 377 ◽  
Author(s):  
Richard S. Crandall ◽  
Martin W. Carlen ◽  
Klaus Lips ◽  
Yueqin Xu
Keyword(s):  
Elevated Temperature ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Type A ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Hole Trapping ◽  
P Type ◽  
Hydrogenated Amorphous

ABSTRACTWe discuss the subtle effects involved in observing slow dangling bond relaxation by studying capacitance transients in p-type hydrogenated amorphous silicon (a-Si:H). The data suggest that neutral dangling bonds are reversibly converted into metastable positive charged dangling bonds by hole trapping. These metastable positive dangling bonds reconvert to neutral dangling bonds upon annealing at elevated temperature. The annealing kinetics for this process are the same as those observed for annealing of quenched in conductivity changes in p-type a-Si:H.

Defect States Due to Silicon Dangling Bonds at the Si(100)/SiO2 Interface and the Passivation by Hydrogen Atoms

1999 ◽  
Vol 592 ◽  
Author(s):  
C. Kaneta ◽  
T. Yamasaki ◽  
T. Uchiyama ◽  
T. Uda ◽  
K. Terakura
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Interface States ◽  
The Other ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Defect States ◽  
Hydrogen Atoms ◽  
The Density Functional Theory ◽  
Upper Level

ABSTRACTThe defect states due to the Si dangling-bonds at the Si(100)/SiO2 interface is investigated by employing the first-principles method based on the density functional theory. Two prototypes of the defects at the interface are considered. One exists on one end of a Si-Si dimer. On the other hand, the other exists on an edge of a Si-O-Si bridge. The electronic structures for these systems were calculated to investigate the interface states. For the former, two defect states strongly localizing on the silicon dangling bond at the interface appear in the band gap. The latter defect also generates two defect states. But the upper level is in the conduction band, while the lower level is in the band gap. It is also shown that the interface states completely disappear by introducing a H atom into the interface and terminating the dangling bonds. Our results suggest the silicon dangling-bond on a Si-Si dimer with no adjacent O atoms as a candidate for the Pb1 center.

Optical and electronic properties of amorphous SiNx:H alloy films

1985 ◽  
Vol 63 (6) ◽  
pp. 846-851 ◽  
Author(s):  
T. V. Herak ◽  
R. D. McLeod ◽  
M. G. Collett ◽  
K. C. Kao ◽  
H. C. Card ◽  
...  
Keyword(s):  
Nitrogen Content ◽  
Electronic Properties ◽  
Optical Excitation ◽  
Dark Conductivity ◽  
Dangling Bond ◽  
Alloy Films ◽  
Optical And Electronic Properties ◽  
Rf Glow Discharge ◽  
Gap States ◽  
Induced Changes

The optical and electronic properties of a-SiNx:H alloy films fabricated by rf glow discharge have been measured for 0 ≤ x ≤ 0.6. The material is dispersive over the range of photon energies 0.5 ≤ hv ≤ 3.5 eV. The optical gap is about 1.65 eV and is practically independent of x for 0.1 < x < 0.4, but it increases rapidly with increasing x for 0 < x < 0.1 and x > 0.4. For x > 0.6 the refractive index approaches the value for Si3N4. The dark conductivity, the photoconductivity, and the ratio of the photoconductivity to the dark conductivity are enhanced by nitrogen incorporation when appropriate nitrogen content is used. All the experimental results indicate that the incorporated nitrogen does not act as a dopant, but rather acts as a dangling-bond compensator. Photo-induced changes in both dark conductivity and photoconductivity due to high-intensity optical excitation have been observed. The degree of such changes decreases with increasing nitrogen content. This phenomenon is attributed to the photo-induced change in the microstructure of the films that leads to a change in both the density and the distribution of gap states.

ESR Measurements of a-Si:H and a-Si0.5Ge0.5:H Films Under Solid-Phasecrystallization

1999 ◽  
Vol 557 ◽  
Author(s):  
I. H. Yun ◽  
O. H. Roh ◽  
J.-K. Lee
Keyword(s):  
Spin Density ◽  
Annealing Time ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
X Ray Diffraction ◽  
X Ray ◽  
G Value ◽  
In The Beginning

AbstractWe have investigated the solid-phase crystallization of a-Si1-xGex:H (x=0 and 0.5) films by using electron spin resonance and x-ray diffraction. The films were deposited on Coming 1737 glass in a plasma-enhanced chemical vapor deposition system using SiH4 and GeH4 gases. The films were then annealed to be crystallized at 600°C. It was observed that, for the a-Si:H film, both the spin density and the g-value first increased with annealing time, and then rapidly decreased as the film was crystallized. For the a-Si0.5Ge0.5:H film, the Ge dangling bond spin density increased from 3 × 1018 cm-3 to 2 × 1019 cm3 for the first stage of annealing and then decreased to 3 × 1017 cm-3 after being crystallized; the Si dangling bond spin density just increased to about 2 × 1017 cm-3 and remained nearly constant for further annealing. It is thought that exodiffusion of hydrogen resulted in the increase of spin density in the beginning, and then some portions of amorphous components were converted into the crystalline phase by further annealing. And the keen correlation between the dependence of x-ray peak intensity and the dependence of Ge dangling bond spin density on the annealing time suggests that the Ge dangling bonds rather than Si dangling bonds play an important role in the crystallization of the Si0.5Ge0.5 film.

ESR in 13C Enriched a-Si1−xCx:H

1989 ◽  
Vol 149 ◽  
Author(s):  
Xixiang Xu ◽  
Hideo Kidoh ◽  
Akiharu Morimoto ◽  
Minoru Kumeda ◽  
Tatsuo Shimizu
Keyword(s):  
Hyperfine Interaction ◽  
Single Line ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Doublet Line ◽  
Small X

ABSTRACTThe effect of using the 13C isotope on the ESR signal in a-Si1−x Cx:H is investigated. The ESR linewidth increases with increasing the C content for a-Si1−x Cx.:H with 12C, while it is almost unchanged for a-Si1−x Cx:H with 12C. However, a doublet line which is expected for a C dangling bond having the hyperfine interaction with the 13C nucleus was not detected. In the range of a small x, it is possible that Si dangling bonds with 13C at the back bonds are the origin of the wide ESR signal. In the range of a large x, 13C dangling bonds should exist, but they are in a clustered form, being observed as an exchange narrowed single line instead of the hyperfine split line.

scholarly journals On the spectral features of dangling bonds in CH4/H2O amorphous ice mixtures

2021 ◽  
Vol 23 (15) ◽  
pp. 9532-9538
Author(s):  
Belén Maté ◽  
Miguel Á. Satorre ◽  
Rafael Escribano
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Spectral Features ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Functional Theory ◽  
Frequency Shifts ◽  
Amorphous Ice

Dangling bond bands of pure H2O and CH4/H2O ice mixtures are studied at density functional theory levels. Agreement with experiments on frequency shifts and intensity enhancements of infrared dangling bond bands was found.

Increased Conductivity in P-Type Hydrogenated Amorphous Silicon

1986 ◽  
Vol 70 ◽  
Author(s):  
Jacques I. Pankove ◽  
Joseph Dresner
Keyword(s):  
Atomic Hydrogen ◽  
Radiative Recombination ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Implantation Damage ◽  
Order Of Magnitude ◽  
Recombination Centers ◽  
Neutralization Process ◽  
P Type ◽  
Hydrogenated Amorphous

ABSTRACTThe low conductivity of B-doped a-Si:H is usually attributed to the fact that only a small fraction of the boron is tetrahedrally coordinated. In the presence of hydrogen, that small fraction can be inactivated via the acceptor-neutralization process that was described for the case of B-doped crystalline Si. When a B-doped sample of a-Si:H was annealed to drive away hydrogen near the boron atoms, the conductivity increases by a factor of 600. Although a-Si:H can be doped either n-type or p-type, the doping efficiency is orders of magnitude poorer than in crystalline Si. In fact the doping efficiency of boron is one order of magnitude lower than that of phosphorus. Several models account for the low doping efficiency of a-Si:H, the most plausible being the location of B in a trigonal site, i.e. surrounded by three Si-atoms as shown in Fig. 1. Such a center is neutral and cannot act as an acceptor. The present work is an offshoot of our study of the hydrogenation of dangling bonds in crystalline Si (1). The awareness that H ties to a Si dangling bond more strongly than another Si-atom led us to passivate the numerous dangling bonds on the surface a Si-crystal. Then, we passivated dangling bonds in grain boundaries and in dislocations and we showed that ion implantation damage also could be neutralized by atomic hydrogen thus removing non-radiative recombination centers and allowing the luminescent transitions to become more efficient.

Sign in / Sign up

Export Citation Format

Share Document