246,694 research outputs found
Recrystallization of epitaxial GaN under indentation
We report recrystallization of epitaxial (epi-) GaN(0001) film under
indentation.Hardness value is measured close to 10 GPa, using a Berkovich
indenter. Pop-in burst in the loading line indicates nucleation of dislocations
setting in plastic motion of lattice atoms under stress field for the
recrystallization process. Micro-Raman studies are used to identify the
recrystallization process. Raman area mapping indicates the crystallized
region. Phonon mode corresponding to E2(high) close to 570 cm-1 in the as-grown
epi-GaN is redshifted to stress free value close to 567 cm-1 in the indented
region. Evolution of A1(TO) and E1(TO) phonon modes are also reported to
signify the recrystallization process.Comment: 10 pages, 3 figures
Industrial capability to chem-mill aluminum alloy 2219 in T-37 and T-87
Procedures and chemical baths were developed for chem-milling aluminum alloy 2219. Using a series of sample etchings, it was found that good etching results could be obtained by using 'white plastic for porcelain repair (toluol, xylol, and petroleum distillates)' on top of cellosolve acetate as resist coatings and ferric chloride as on etchant
Surface optical Raman modes in InN nanostructures
Raman spectroscopic investigations are carried out on one-dimensional
nanostructures of InN,such as nanowires and nanobelts synthesized by chemical
vapor deposition. In addition to the optical phonons allowed by symmetry; A1,
E1 and E2(high) modes, two additional Raman peaks are observed around 528 cm-1
and 560 cm-1 for these nanostructures. Calculations for the frequencies of
surface optical (SO) phonon modes in InN nanostructures yield values close to
those of the new Raman modes. A possible reason for large intensities for SO
modes in these nanostructures is also discussed.Comment: 13 pages, 4 figures, Submitted in Journa
Quantum multiparty key distribution protocol without use of entanglement
We propose a quantum key distribution (QKD) protocol that enables three
parties agree at once on a shared common random bit string in presence of an
eavesdropper without use of entanglement. We prove its unconditional security
and analyze the key rate.Comment: 8 pages, no figur
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