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.

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.

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.

Bond equilibrium theory for Te-rich liquid Tl–Te alloys

1977 ◽  
Vol 55 (11) ◽  
pp. 1930-1936 ◽  
Author(s):  
Melvin Cutler
Keyword(s):  
Free Energy ◽  
Good Description ◽  
Hole Concentration ◽  
Enthalpy Of Mixing ◽  
Dangling Bond ◽  
Fermi Model ◽  
Bond Model ◽  
Independent Information ◽  
Molecular Bond ◽  
Rich Liquid

Recent work has provided independent information about the behavior of the hole concentration c in TlxTe1−x as a function of temperature T and composition x in the range 0.2 ≤ x ≤ 0.6. This makes possible a critical reexamination of a molecular bond model for the structure of the alloy, in which holes are generated by broken Te—Te bonds. The earlier theory is revised to formulate an unrestricted independent bond model (ibm), for which the equations are simple and have obvious physical interpretations. This provides a good description of c(T) but only a qualitatively correct c(x). Using a Thomas–Fermi model for the screening interaction between holes and the acceptor ions, it is shown that the equilibrium constant can be expected to increase rapidly with c at large enough values. A modification in which the free energy of a dangling bond is decreased by proximity to a Tl—Te bond is found to significantly improve the result for c(x). The thermochemical behavior is derived. The entropy of mixing is in fair agreement with experiment, but the enthalpy of mixing is grossly wrong. This reflects the neglect of intermolecular interactions in the theory, which, it seems, can easily account for the remaining discrepancies in the predicted behavior of c.

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.

Nature of Charged Metastable Defects in Network Rebonding Model

2002 ◽  
Vol 715 ◽  
Author(s):  
R. Biswas ◽  
B. C. Pan
Keyword(s):  
Low Temperature ◽  
Rate Equations ◽  
Atomistic Model ◽  
Dangling Bonds ◽  
Defect Creation ◽  
Higher Temperature ◽  
Kinetics Of Degradation ◽  
Kinetics Of ◽  
Defect Densities ◽  
Positively Charged

AbstractWe recently developed an atomistic model of metastability of a-Si:H, where defect creation is driven by the breaking of weak silicon bonds. The kinetics of degradation in this model is simulated with coupled rate equations that show t1/3 kinetics of defect creation and saturation behavior similar to experiment. Saturated defect densities of neutral dangling bonds are accompanied by a much smaller density of negatively charged floating bonds and positively charged dangling bonds (D+). We propose a two-step annealing mechanism where the positively charged D+ dangling bonds are annealed at low temperature and the D0 at higher temperature -which accounts for hysteresis in mobility lifetime products.

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.

Light-Intensity Dependence of the Staebler-Wronski Effect in a-Si:H with Various Densities of Defects

2005 ◽  
Vol 862 ◽  
Author(s):  
Minoru Kumeda ◽  
Ryohei Sakai ◽  
Akiharu Morimoto ◽  
Tatsuo Shimizu
Keyword(s):  
Light Intensity ◽  
Weak Dependence ◽  
Rate Equations ◽  
Dangling Bonds ◽  
Illumination Time ◽  
Intensity Dependence ◽  
Weak Light ◽  
Staebler Wronski Effect

AbstractThe light-intensity dependence of the photocreation of dangling bonds (DBs) were investigated for a-Si:H films with increasing density of defects before light soaking. Samples in which the density of neutral DBs had been increased by annealing at 400 C for 1 h exhibited a weak light-intensity dependence of the photocreated DBs compared to that for the as-deposited sample. Furthermore, the sample which had been illuminated with a light intensity of 1 W/cm2 for 1 h also showed a weak dependence. The results can be qualitatively explained by using rate equations for the densities of DBs and floating bonds (FBs) based on the FB-mediated photocreation of DBs. When both the densities of DBs and FBs before illumination increase, the light-intensity dependence of the DB density for a moderate value of the illumination time becomes weaker, qualitatively consistent with the observed results.

Thermal annealing effects of dangling bonds in hydrogenated polymorphous silicon

2008 ◽  
Vol 104 (5) ◽  
pp. 053715 ◽  
Author(s):  
K. Takeda ◽  
K. Morigaki ◽  
H. Hikita ◽  
P. Roca i Cabarrocas
Keyword(s):  
Thermal Annealing ◽  
Dangling Bonds ◽  
Annealing Effects

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.

THE CHEMICAL BOND IN SEMICONDUCTORS: THE GROUP V B TO VII B ELEMENTS AND COMPOUNDS FORMED BETWEEN THEM

1956 ◽  
Vol 34 (12A) ◽  
pp. 1369-1376 ◽  
Author(s):  
E. Mooser ◽  
W. B. Pearson
Keyword(s):  
Optical Properties ◽  
Chemical Bond ◽  
Chemical Bonding ◽  
Valence Bond ◽  
Electrical And Optical Properties ◽  
Group V ◽  
New Model ◽  
Bond Model

A brief review is first given of the developments which led to an understanding of the important role played by chemical bonding in semiconductors. The properties of the Group V B to VII B elements and of some compounds formed between these elements are then considered according to the valence bond model of Pauling. This leads to the conclusion that the band scheme in these substances is somewhat different to that which has been generally accepted, and we discuss the new model in relation to their electrical and optical properties.

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