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693 results on '"Ridgway M"'

156. Gettering of Pd to implantation-induced nanocavities in Si

Author

Brett, D. A., de M. Azevedo, G., Llewellyn, D. J., Ridgway, M. C., Brett, D. A., de M. Azevedo, G., Llewellyn, D. J., and Ridgway, M. C.

Abstract

The gettering of Pd to nanocavities in Si for implantation doses ranging from 5×10¹³ to 1×10¹⁵ cm¯² and annealing temperatures ranging from 750 to 1050 °C was investigated using Rutherford backscattering and cross-sectional transmission electron microscopy. For a given annealing temperature, the gettering efficiency increased as the dose decreased. For a given dose, maximum gettering efficiency was achieved at the intermediate temperatures studied. Competition between silicide formation and nanocavity gettering limited gettering efficiency.

Published
2003

157. Ferromagnetic Ga₁ˍₓ Mnₓ As produced by ion implantation and pulsed-laser melting

Author

Scarpulla, M. A., Dubon, O. D., Yu, K. M., Monteiro, O., Pillai, M. R., Aziz, M. J., Ridgway, M. C., Scarpulla, M. A., Dubon, O. D., Yu, K. M., Monteiro, O., Pillai, M. R., Aziz, M. J., and Ridgway, M. C.

Abstract

We demonstrate the formation of ferromagneticGa₁ˍₓMnₓAsfilms by Mn ion implantation into GaAs followed by pulsed-laser melting. Irradiation with a single excimer laser pulse results in the epitaxial regrowth of the implanted layer with Mn substitutional fraction up to 80% and effective Curie temperature up to 29 K for samples with a maximum Mn concentration of x≈0.03. A remanent magnetization persisting above 85 K has been observed for samples with x≈0.10, in which 40% of the Mn resides on substitutional lattice sites. We find that the ferromagnetism in Ga₁ˍₓMnₓAs is rather robust to the presence of structural defects.

Published
2003

158. Mutual passivation of group IV donors and nitrogen in diluted GaNₓAs₁ˍₓ alloys

Author

Yu, K. M., Walukiewicz, W., Wu, J., Shan, W., Beeman, J. W., Scarpulla, M. A., Dubon, O. D., Ridgway, M. C., Mars, D. E., Chamberlin, D. R., Yu, K. M., Walukiewicz, W., Wu, J., Shan, W., Beeman, J. W., Scarpulla, M. A., Dubon, O. D., Ridgway, M. C., Mars, D. E., and Chamberlin, D. R.

Abstract

We demonstrate the mutual passivation phenomenon of Ge donors and isovalent N in highly mismatched alloy GaNₓAs₁ˍₓdoped with Ge. Layers of this alloy were formed by the sequential implantation of Ge and N ions followed by pulsed laser melting and rapid thermal annealing. The mutual passivation effect results in the electrical deactivation of GeGa donors (Ge on Ga sites) and suppression of the NAs (N on As sites) induced band gap narrowing through the formation of GeGa–NAs nearest neighbor pairs. These results in combination with the analogous effect observed in Si-doped GaNₓAs₁ˍₓ provide clear evidence of the general nature of the mutual passivation phenomenon in highly mismatched semiconductor alloys.

Published
2003

170. Swift Heavy Ion Irradiation of Cobalt Nanoparticles

Author

Sprouster, D. J., primary, Giulian, R., additional, Schnohr, C. S., additional, Kluth, P., additional, Araujo, L. L., additional, Byrne, A. P., additional, Foran, G. J., additional, Ridgway, M. C., additional, and Paniago, Rogério Magalhaes, additional

Published
2009
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177. Formation of diluted III–V nitride thin films by N ion implantation

Author

Yu, K. M., Walukiewicz, W., Wu, J., Beeman, J. W., Ager, J. W., Haller, E. E., Shan, W., Xin, H. P., Tu, C. W., Ridgway, M. C., Yu, K. M., Walukiewicz, W., Wu, J., Beeman, J. W., Ager, J. W., Haller, E. E., Shan, W., Xin, H. P., Tu, C. W., and Ridgway, M. C.

Abstract

iluted III–Nₓ–V₁ˍₓ alloys were successfully synthesized by nitrogen implantation into GaAs,InP, and AlyGa1−yAs. In all three cases the fundamental band-gap energy for the ion beam synthesized III–Nₓ–V₁ˍₓ alloys was found to decrease with increasing N implantation dose in a manner similar to that observed in epitaxially grownGaNₓAs1−x and InNₓP₁ˍₓalloys. In GaNₓAs₁ˍₓ the highest value of x (fraction of “active” substitutional N on As sublattice) achieved was 0.006. It was observed that NAs is thermally unstable at temperatures higher than 850 °C. The highest value of x achieved in InNₓP₁ˍₓ was higher, 0.012, and the NP was found to be stable to at least 850 °C. In addition, the N activation efficiency in implantedInNₓP₁ˍₓ was at least a factor of 2 higher than that in GaNₓAs₁ˍₓ under similar processing conditions. AlyGa1−yNₓAs₁ˍₓ had not been made previously by epitaxial techniques. N implantation was successful in producing AlyGa1−yNₓAs₁ˍₓalloys. Notably, the band gap of these alloys remains direct, even above the value of y (y>0.44) where the band gap of the host material is indirect.

Published
2001

178. Direct observation of irradiation-induced nanocavity shrinkage in Si

Author

Zhu, X. F., Williams, J. S., Conway, M. J., Ridgway, M. C., Fortuna, F., Ruault, M.-O., Bernas, H., Zhu, X. F., Williams, J. S., Conway, M. J., Ridgway, M. C., Fortuna, F., Ruault, M.-O., and Bernas, H.

Abstract

Nanocavities in Si substrates, formed by conventional H implantation and thermal annealing, are shown to evolve in size during subsequent Si irradiation. Both ex situ and in situ analytical techniques were used to demonstrate that the mean nanocavity diameter decreases as a function of Si irradiation dose in both the crystalline and amorphous phases. Potential mechanisms for this irradiation-induced nanocavity evolution are discussed. In the crystalline phase, the observed decrease in diameter is attributed to the gettering of interstitials. When the matrix surrounding the cavities is amorphized, cavity shrinkage may be mediated by one of two processes: nanocavities can supply vacancies into the amorphous phase and/or the amorphous phase may flow plastically into the nanocavities. Both processes yield the necessary decrease in density of the amorphous phase relative to crystalline material.

Published
2001

179. Cutting Off Aid To Expropriators.

Author

Hall Jr., Ridgway M.

Subjects
*INTERNATIONAL economic assistance, *ECONOMIC sanctions, UNITED States economic policy, 1961-1971
Abstract

Examines the implications of the United States government's termination of all foreign aid to Peru under the Hickenlooper Amendment. Effect of Peru's decision to nationalize the holdings of International Petroleum Corp.; Background of the Hickenlooper Amendment; Illustration of the ineffectiveness of economic sanctions; Problems with the Hickenlooper Amendment; Calls by the Task Force on International Development for President Richard Nixon to seek repeal of the Hickenlooper Amendment.

Published
1971

181. Fine Structure in Swift Heavy Ion Tracks in AmorphousSiO2

Author

Kluth, P., primary, Schnohr, C. S., additional, Pakarinen, O. H., additional, Djurabekova, F., additional, Sprouster, D. J., additional, Giulian, R., additional, Ridgway, M. C., additional, Byrne, A. P., additional, Trautmann, C., additional, Cookson, D. J., additional, Nordlund, K., additional, and Toulemonde, M., additional

Published
2008
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190. Xuet al.Reply

Author

Xu, Q., primary, Sharp, I. D., additional, Yuan, C. W., additional, Yi, D. O., additional, Liao, C. Y., additional, Glaeser, A. M., additional, Minor, A. M., additional, Beeman, J. W., additional, Ridgway, M. C., additional, Kluth, P., additional, Ager, J. W., additional, Chrzan, D. C., additional, and Haller, E. E., additional

Published
2007
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193. Superheating and supercooling of Ge nanocrystals embedded in SiO2

Author

Xu, Q, primary, Sharp, I D, additional, Yuan, C W, additional, Yi, D O, additional, Liao, C Y, additional, Glaeser, A M, additional, Minor, A M, additional, Beeman, J W, additional, Ridgway, M C, additional, Kluth, P, additional, Ager, J W, additional, Chrzan, D C, additional, and Haller, E E, additional

Published
2007
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