76 research outputs found
Multi-Cycle Test with Partial Observation on Scan-Based BIST Structure
Field test for reliability is usually performed with small amount of memory resource, and it requires a new technique which might be somewhat different from the conventional manufacturing tests. This paper proposes a novel technique that improves fault coverage or reduces the number of test vectors that is needed for achieving the given fault coverage on scan-based BIST structure. We evaluate a multi-cycle test method that observes the values of partial flip-flops on a chip during capture-mode. The experimental result shows that the partial observation achieves fault coverage improvement with small hardware overhead than the full observation.2011 Asian Test Symposium (ATS), 20-23 Nov. 2011, New Delhi, Indi
Electron emission from conduction band of diamond with negative electron affinity
Experimental evidence explaining the extremely low-threshold electron
emission from diamond reported in 1996 has been obtained for the first time.
Direct observation using combined ultraviolet photoelectron spectroscopy/field
emission spectroscopy (UPS/FES) proved that the origin of field-induced
electron emission from heavily nitrogen (N)-doped chemical vapour deposited
(CVD) diamond was at conduction band minimum (CBM) utilising negative electron
affinity (NEA). The significance of the result is that not only does it prove
the utilisation of NEA as the dominant factor for the extremely low-threshold
electron emission from heavily N-doped CVD diamond, but also strongly implies
that such low-threshold emission is possible from other types of diamond, and
even other materials having NEA surface. The low-threshold voltage, along with
the stable intensity and remarkably narrow energy width, suggests that this
type of electron emission can be applied to develop a next generation vacuum
nano-electronic devices with long lifetime and high energy resolution.Comment: 17 pages, 4 figures, Phys. Rev. B in pres
Tuning the Fr\"ohlich exciton-phonon scattering in monolayer MoS2
A direct band gap, remarkable light-matter coupling as well as strong
spin-orbit and Coulomb interaction establish two-dimensional (2D) crystals of
transition metal dichalcogenides (TMDs) as an emerging material class for
fundamental studies as well as novel technological concepts. Valley selective
optical excitation allows for optoelectronic applications based on the momentum
of excitons. In addition to lattice imperfections and disorder, scattering by
phonons is a significant mechanism for valley depolarization and decoherence in
TMDs at elevated temperatures preventing high-temperature valley polarization
required for realistic applications. Thus, a detailed knowledge about strength
and nature of the interaction of excitons with phonons is vital. We directly
access exciton-phonon coupling in charge tunable single layer MoS2 devices by
polarization resolved Raman spectroscopy. We observe a strong defect mediated
coupling between the long-range oscillating electric field induced by the
longitudinal optical (LO) phonon in the dipolar medium and the exciton. We find
that this so-called Fr\"ohlich exciton LO-phonon interaction is suppressed by
doping. This suppression correlates with a distinct increase of the degree of
valley polarization of up to 20 % even at elevated temperatures of 220 K. Our
result demonstrates a promising strategy to increase the degree of valley
polarization towards room temperature valleytronic applications.Comment: 18 pages, 3 figures, S
Cavity-control of interlayer excitons in van der Waals heterostructures
Monolayer transition metal dichalcogenides integrated in optical microcavities host exciton-polaritons as a hallmark of the strong light-matter coupling regime. Analogous concepts for hybrid light-matter systems employing spatially indirect excitons with a permanent electric dipole moment in heterobilayer crystals promise realizations of exciton-polariton gases and condensates with inherent dipolar interactions. Here, we implement cavity-control of interlayer excitons in vertical MoSe2-WSe2 heterostructures. Our experiments demonstrate the Purcell effect for heterobilayer emission in cavity-modified photonic environments, and quantify the light-matter coupling strength of interlayer excitons. The results will facilitate further developments of dipolar exciton-polariton gases and condensates in hybrid cavity – van der Waals heterostructure systems
Cavity-control of interlayer excitons in van der Waals heterostructures
Monolayer transition metal dichalcogenides integrated in optical microcavities host exciton-polaritons as a hallmark of the strong light-matter coupling regime. Analogous concepts for hybrid light-matter systems employing spatially indirect excitons with a permanent electric dipole moment in heterobilayer crystals promise realizations of exciton-polariton gases and condensates with inherent dipolar interactions. Here, we implement cavity-control of interlayer excitons in vertical MoSe2-WSe2 heterostructures. Our experiments demonstrate the Purcell effect for heterobilayer emission in cavity-modified photonic environments, and quantify the light-matter coupling strength of interlayer excitons. The results will facilitate further developments of dipolar exciton-polariton gases and condensates in hybrid cavity - van der Waals heterostructure systems
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