Direct absorption edge in GeSiSn alloys

Author(s):  
V. R. D’Costa ◽  
Y.-Y. Fang ◽  
J. Tolle ◽  
J. Kouvetakis ◽  
J. Menéndez ◽  
...  
1987 ◽  
Vol 61 (5) ◽  
pp. 275-278 ◽  
Author(s):  
K. Strössner ◽  
S. Ves ◽  
Chul Koo Kim ◽  
M. Cardona

1967 ◽  
Vol 11 (4) ◽  
pp. 138-140 ◽  
Author(s):  
David Redfield ◽  
Martin A. Afromowitz

1977 ◽  
Vol 15 (2) ◽  
pp. 875-879 ◽  
Author(s):  
Benjamin Welber ◽  
Manuel Cardona ◽  
Yet-Ful Tsay ◽  
Bernard Bendow

1991 ◽  
Vol 69 (3-4) ◽  
pp. 324-328 ◽  
Author(s):  
M. Parenteau ◽  
C. Carlone ◽  
M. Aubin ◽  
S. M. Khanna ◽  
W. T. Anderson ◽  
...  

Semi-insulating liquid encapsulated Czochralski GaAs wafers were submitted to irradiation with 1 MeV neutrons, thermal neutrons, 7 MeV electrons, and white electrons (up to 7 MeV). The direct absorption edge was then studied by means of transmission (T = 15 K) and thermoreflectance (T = 35 and 51 K) measurements. Thermoreflectance spectra showed that the position of the exciton does not shift after irradiation with 1 MeV neutrons, but that its broadening parameter Γ increases as the fluence increases. Transmission measurements have revealed the presence of two acceptor levels (C and Zn) in the unirradiated samples. The absorption associated with these impurities increased by a factor of 10 after irradiation with 1 MeV neutrons. This effect was not produced by the three other types of radiation. However, an absorption tail extending well below the direct edge is seen after irradiation with all four types of particles. A model proposed by Toyozawa fits this continuum quite well, suggesting that irradiation causes amorphization of the crystal. The rate of introduction of defects and its dependence on irradiation fluence is different for each type of radiation.


1980 ◽  
Vol 21 (10) ◽  
pp. 4879-4883 ◽  
Author(s):  
H. Müller ◽  
R. Trommer ◽  
M. Cardona ◽  
P. Vogl

1966 ◽  
Vol 17 (6) ◽  
pp. 302-304 ◽  
Author(s):  
R. A. Roberts ◽  
D. M. Roessler ◽  
W. C. Walker

1985 ◽  
Vol 56 (6) ◽  
pp. 479-483 ◽  
Author(s):  
S. Ves ◽  
K. Strössner ◽  
N.E. Christensen ◽  
Chul Koo Kim ◽  
M. Cardona

Author(s):  
R. L. Stears

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.


1979 ◽  
Vol 40 (3) ◽  
pp. 315-319 ◽  
Author(s):  
M. Escorne ◽  
A. Mauger ◽  
C. Godart ◽  
J.C. Achard

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