4,531,805 research outputs found
The formation of the Christian biblical canon
Reviewed Book: McDonald, Lee M. The formation of the Christian biblical canon. Peabody, Mass: Hendrickson Pubs, 1995
Exact partition function in ABJM theory deformed by mass and Fayet-Iliopoulos terms
We exactly compute the partition function for ABJM
theory on deformed by mass and Fayet-Iliopoulos parameter
. For , the partition function has an infinite number of
Lee-Yang zeros. For general , in the decompactification limit the theory
exhibits a quantum (first-order) phase transition at .Comment: 11 pages, 1 figure. v2: references adde
Fabrication technology for high light-extraction ultraviolet thin-film flip-chip (UV TFFC) LEDs grown on SiC
The light output of deep ultraviolet (UV-C) AlGaN light-emitting diodes
(LEDs) is limited due to their poor light extraction efficiency (LEE). To
improve the LEE of AlGaN LEDs, we developed a fabrication technology to process
AlGaN LEDs grown on SiC into thin-film flip-chip LEDs (TFFC LEDs) with high
LEE. This process transfers the AlGaN LED epi onto a new substrate by
wafer-to-wafer bonding, and by removing the absorbing SiC substrate with a
highly selective SF6 plasma etch that stops at the AlN buffer layer. We
optimized the inductively coupled plasma (ICP) SF6 etch parameters to develop a
substrate-removal process with high reliability and precise epitaxial control,
without creating micromasking defects or degrading the health of the plasma
etching system. The SiC etch rate by SF6 plasma was ~46 \mu m/hr at a high RF
bias (400 W), and ~7 \mu m/hr at a low RF bias (49 W) with very high etch
selectivity between SiC and AlN. The high SF6 etch selectivity between SiC and
AlN was essential for removing the SiC substrate and exposing a pristine,
smooth AlN surface. We demonstrated the epi-transfer process by fabricating
high light extraction TFFC LEDs from AlGaN LEDs grown on SiC. To further
enhance the light extraction, the exposed N-face AlN was anisotropically etched
in dilute KOH. The LEE of the AlGaN LED improved by ~3X after KOH roughening at
room temperature. This AlGaN TFFC LED process establishes a viable path to high
external quantum efficiency (EQE) and power conversion efficiency (PCE) UV-C
LEDs.Comment: 22 pages, 6 figures. (accepted in Semiconductor Science and
Technology, SST-105156.R1 2018
Possible Triplet Electron Pairing and an Anisotropic Spin Susceptibility in Organic Superconductors (TMTSF)_2 X
We argue that (TMTSF)_2 PF_6 compound under pressure is likely a triplet
superconductor with a vector order parameter d(k) \equiv (d_a(k) \neq 0, d_c(k)
= ?, d_{b'}(k) = 0); |d_a(k)| > |d_c(k)|. It corresponds to an anisotropic spin
susceptibility at T=0: \chi_{b'} = \chi_0, \chi_a \ll \chi_0, where \chi_0 is
its value in a metallic phase. [The spin quantization axis, z, is parallel to a
so-called b'-axis]. We show that the suggested order parameter explains why the
upper critical field along the b'-axis exceeds all paramagnetic limiting
fields, including that for a nonuniform superconducting state, whereas the
upper critical field along the a-axis (a \perp b') is limited by the Pauli
paramagnetic effects [I. J. Lee, M. J. Naughton, G. M. Danner and P. M.
Chaikin, Phys. Rev. Lett. 78, 3555 (1997)]. The triplet order parameter is in
agreement with the recent Knight shift measurements by I. J. Lee et al. as well
as with the early results on a destruction of superconductivity by nonmagnetic
impurities and on the absence of the Hebel-Slichter peak in the NMR relaxation
rate.Comment: 4 pages, 1 eps figur
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