Subband Recombination in a-Si:H

1992 ◽  
Vol 258 ◽  
Author(s):  
S.Q. Gu ◽  
P.C. Taylor
Keyword(s):  
Excitation Energy ◽  
Valence Band ◽  
Low Temperatures ◽  
Strong Dependence ◽  
Low Energy ◽  
Band Tail ◽  
Low Energy Tail

ABSTRACTPhotoluminescence (PL) in a-Si:H has been studied as a function of excitation energy from above the gap down to well below the gap. Although the width of the PL peak shows no strong dependence on the excitation energy at low temperatures, the low energy tail of bandtail PL exhibits an approximately exponential drop with decreasing energy, I ≈ exp(hν/δE), where δE increases with decreasing excitation energy for excitation energy below about 1.65 eV. This behavior is attributed to the slow downward hopping of holes in the valence band tail that are generated below a thermalization threshold at low temperatures.

Photoluminescence in Hydrogenated Silicon-Germanium Alloys

1987 ◽  
Vol 95 ◽  
Author(s):  
R. Ranganathan ◽  
M. Gal ◽  
J. M. Viner ◽  
P. C. Taylor
Keyword(s):  
Valence Band ◽  
Conduction Band ◽  
Silicon Germanium ◽  
Low Energy ◽  
Dangling Bond ◽  
Band Tail ◽  
Hydrogenated Silicon ◽  
Bond State ◽  
Constant Magnitude ◽  
Low Energy Tail

AbstractResults of a detailed study of photoluminescence (PL) in the a-Si1−xGex:H system are presented. Many samples exhibit a low energy “tail” to the PL efficiency which is of constant magnitude independent of x. There is a departure from this behavior when a low energy PL peak near 0.8–0.9 eV is present. The position of the low energy PL peak is independent of Ge concentration. It has been suggested that this PL transition is from an electron in the conduction band tail into a silicon dangling bond state. As Ge is added to a-Si:H it is the edge of the conduction band which decreases in energy while the valence band remains relatively constant in energy. It is therefore unlikely that the low energy PL is due to a transition from the conduction band into a silicon dangling bond state because the energy of the silicon dangling bond with respect to the valence band is probably essentially independent of Ge content. If the PL which peaks near 0.8 eV results from a transition which involves a silicon dangling bond, then the transition may be from the dangling bond to the valence band.

Optical absorption of crystalline tetracene in the low-energy tail of the So→S1 transition

1975 ◽  
Vol 32 (1) ◽  
pp. K37-K39 ◽  
Author(s):  
J. Berrehar ◽  
M. Schott ◽  
P. Delannoy
Keyword(s):  
Optical Absorption ◽  
Low Energy ◽  
Low Energy Tail

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.

scholarly journals Martensitic transformation in the systems based on Fe-Ni compositions in strong pulsed magnetic fields

2021 ◽  
pp. 22-29 ◽  
Author(s):  
I. Zolotarevskii
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Magnetic Fields ◽  
Temperature Dependence ◽  
Strong Magnetic Field ◽  
Low Temperatures ◽  
Strong Dependence ◽  
Magnetic Interaction ◽  
Iron Alloys ◽  
Pulsed Magnetic Fields

Purpose of work. To ascertain the causes of the abnormally large displacement of the martensitic point in steels and iron alloys in strong pulsed magnetic fields at low temperatures. Research methods. Generalization of experimental and theoretical investigations of the strong magnetic field influence on the martensitic transformation in steels and iron alloys, taking into account the magnetic state of austenite. The obtained results. The distributions of the martensitic point displacement ΔMS from the content of the main component - iron and the temperature of the martensitic γ → α- transformation beginning (martensitic point MS) in different experiments are obtained. It is shown that the obtained temperature dependence ΔMS(MS) in a strong magnetic field at low temperatures decomposes into two components, one of which correlates with the generalized Clapeyron-Clausius equations, and the other is opposite to it. In addition, it was found that steels and alloys with intense γ → α- transformation in a magnetic field contain at least 72.5% iron (wt), which at low temperatures in the fcc structure is antiferromagnetic. Scientific novelty. The anomalous temperature dependence of the distribution ΔMS(MS) in a strong magnetic field is explained on the basis of quantum representations of the magnetic interaction of atoms in the Fe-Ni system. This effect is associated with a number of other invar effects, in particular, with an abnormally large spontaneous and forced magnetostriction, a strong dependence of the resulting exchange integral on the interatomic distance. The point of view according to which in these alloys in a magnetic field γ → α- transformation occurs by the type of “magnetic first kind phase transformation” is substantiated. It is assumed that the nucleation of the martensitic phase in a magnetic field occurs in (at) local regions of γ- phase with disoriented atomic magnetic moments (with high compression and increased forced magnetostriction). Practical value. The information obtained in this work provides grounds for explaining the kinetic features of the transformation of austenite into martensite in steels and iron alloys.

scholarly journals On Low-Energy Tail Distortions in the Detector Response Function of X-Ray Microcalorimeter Spectrometers

2019 ◽  
Vol 199 (3-4) ◽  
pp. 1046-1054 ◽  
Author(s):  
G. C. O’Neil ◽  
P. Szypryt ◽  
E. Takacs ◽  
J. N. Tan ◽  
S. W. Buechele ◽  
...  
Keyword(s):  
Response Function ◽  
Low Energy ◽  
Detector Response ◽  
Detector Response Function ◽  
X Ray ◽  
Low Energy Tail

Low-energy tail of the giant dipole resonance inMo98andMo100deduced from photon-scattering experiments

2008 ◽  
Vol 77 (6) ◽  
Author(s):  
G. Rusev ◽  
R. Schwengner ◽  
F. Dönau ◽  
M. Erhard ◽  
E. Grosse ◽  
...  
Keyword(s):  
Giant Dipole Resonance ◽  
Low Energy ◽  
Photon Scattering ◽  
Dipole Resonance ◽  
Low Energy Tail

Anomalous Permeation of Low Energy Neon Atoms in Tungsten at Low Temperatures

1986 ◽  
Vol 25 (Part 2, No. 3) ◽  
pp. L240-L243 ◽  
Author(s):  
Susumu Fukatsu ◽  
Tomihiro Hashizume ◽  
Akira Sakai ◽  
Toshio Sakurai ◽  
Shin-ichi Hyodo
Keyword(s):  
Low Temperatures ◽  
Low Energy
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