Tunable RF phase shifters based on Vanadium Dioxide metal insulator transition

This paper presents the design, fabrication, and electrical characterization of a reconfigurable RF capacitive shunt switch that exploits the electro-thermally triggered vanadium dioxide (VO2) insulator to metal phase transition. The RF switch is further exploited to build wide-band RF true-time delay tunable phase shifters. By triggering the VO2 switch insulator to metal transition (IMT), the total capacitance can be reconfigured from the series of two metal-insulator-metal (MIM) capacitors to a single MIM capacitor. The effect of bias voltage on losses and phase shift is investigated, explained, and compared to the state of the art in the field. We report thermal actuation of the devices by heating the devices above VO2 IMT temperature. By cascading multiple stages a maximum of 40° per dB loss close to 7 GHz were obtained

Polarity Control of Top Gated Black Phosphorous FETs by Workfunction Engineering of Pre-Patterned Au and Ag Embedded Electrodes

We propose and experimentally demonstrate top-gated complementary n- and p-type black phosphorous field effect devices (FETs) by engineering the workfunction of pre-patterned electrodes embedded in a SiO2 bottom layer. Pre-patterned electrodes offer the advantages of reducing the exposure time of exfoliated flakes to oxidant agents with respect to top-contacted devices and maximizing the accessible area for sensing applications. The presented devices are realized by mechanical exfoliation of multilayer black phosphorous flakes on top of pre-patterned embedded source and drain contacts. A capping layer consisting of 15-nm thick Al2O3 is deposited to prevent flakes degradation and serves as top gate dielectric. The silicon substrate can be exploited as back gate to program the FETs threshold voltage. We deposited both Au and Ag embedded contacts to investigate the impact of electrodes workfunction on BP FETs polarity. Au contacted devices show p-type conduction with ON/OFF current ratio 140 and holes mobility up to 40 cm(2)V(-1)s(-1). Devices with Ag contacts exhibit prevalent n-type conduction with ON/OFF ratio 1700 and electron mobility 2 cm(2)V(-1)s(-1). The reported results represent a substantial improvement with respect to reported alternative implementations of black phosphorous FETs with pre-patterned, non-embedded electrodes. Moreover, we demonstrate that Ag is a promising metal for electron injection in black phosphorous FETs

WSe2/SnSe2 vdW heterojunction Tunnel FET with subthermionic characteristic and MOSFET co-integrated on same WSe2 flake

Two-dimensional/two-dimensional (2D/2D) heterojunctions form one of the most versatile technological solutions for building tunneling field effect transistors because of the sharp and potentially clean interfaces resulting from van der Waals assembly. Several evidences of room temperature band-to-band tunneling (BTBT) have been recently reported, but only few tunneling devices have been proven to break the Boltzmann limit of the minimum subthreshold slope, 60 mV per decade at 300 K. Here, we report the fabrication and characterization of a vertical p-type Tunnel FET (TFET) co-integrated on the same flake with a p-type MOSFET in a WSe2/SnSe2 material system platform. Due to the selected beneficial band alignment and to a van der Waals device architecture having an excellent heterostructure 2D-2D interface, the reported tunneling devices have a sub-thermionic point swing, reaching a value of 35 mV per decade, while maintaining excellent ON/OFF current ratio in excess of 10(5) at V-DS = 500 mV. The TFET characteristics are directly compared with the ones of a WSe2 MOSFET realized on the very same flake used in the heterojunction. The tunneling device clearly outperforms the 2D MOSFET in the subthreshold region, crossing its characteristic over several orders of magnitude of the output current and providing better digital and analog figures of merit

Towards a general synthesis of di-aza-amino acids containing peptides

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An Experimental Study on Mixed-Dimensional 1D-2D van der Waals Single-Walled Carbon Nanotube-WSe2 Hetero-Junction

This experimental study investigates a novel multi-functional one dimensional-two dimensional (1D-2D) heterojunction made of two different band-gap semiconductors, i.e. single-walled carbon nanotube (SWCNT) and tungsten di-selenide (WSe2). The proposed ultra-scaled van der Waals junction behaves like a p-type field-effect transistor (FET) or a gated p-n diode, depending upon the gate bias. A detailed physical study of charge transportation mechanism is presented in a wide range of applied potentials. The obtained results are important towards scaling nanoelectronics to atomic thicknesses by means of the 1D-2D hybrid junctions with additional multi-functional solid-state devices

First measurement of the Z→μ+μ−Z\rightarrow \mu^+ \mu^- angular coefficients in the forward region of pppp collisions at s=13\sqrt{s}=13 TeV

The first study of the angular distribution of $\mu^+ \mu^-$ pairs produced in the forward rapidity region via the Drell-Yan reaction $pp \rightarrow \gamma^{*}/Z +X \rightarrow l^+ l^- + X$ is presented, using data collected with the LHCb detector at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.1 $\rm{fb}^{-1}$. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the $Z$-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton

Precision measurement of forward ZZ boson production in proton-proton collisions at s=13\sqrt{s} = 13 TeV

A precision measurement of the $Z$ boson production cross-section at $\sqrt{s} = 13$ TeV in the forward region is presented, using $pp$ collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb$^{-1}$. The production cross-section is measured using $Z\rightarrow\mu^+\mu^-$ events within the fiducial region defined as pseudorapidity $2.020$ GeV/$c$ for both muons and dimuon invariant mass $60<M_{\mu\mu}<120$ GeV/$c^2$. The integrated cross-section is determined to be \begin{equation*} \sigma(Z\rightarrow\mu^+\mu^-) = 195.3 \pm 0.2 \pm 1.5 \pm 3.9~pb, \end{equation*} where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions, including a prediction at next-to-next-to-leading order in perturbative quantum chromodynamics and a prediction with resummation

First measurement of the Z→μ+μ−Z\rightarrow \mu^+ \mu^- angular coefficients in the forward region of pppp collisions at s=13\sqrt{s}=13 TeV

The first study of the angular distribution of $\mu^+ \mu^-$ pairs produced in the forward rapidity region via the Drell-Yan reaction $pp \rightarrow \gamma^{*}/Z +X \rightarrow l^+ l^- + X$ is presented, using data collected with the LHCb detector at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.1 $\rm{fb}^{-1}$. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the $Z$-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton

Measurement of the charm mixing parameter yCP−yCPKπy_{CP} - y_{CP}^{K\pi} using two-body D0D^0 meson decays

A measurement of the ratios of the effective decay widths of $D^0 \to \pi^-\pi^+$ and $D^0 \to K^-K^+$ decays over that of $D^0 \to K^-\pi^+$ decays is performed with the LHCb experiment using proton-proton collisions at a centre-of-mass energy of $13 \, \mathrm{TeV}$, corresponding to an integrated luminosity of $6 \, \mathrm{fb^{-1}}$. These observables give access to the charm mixing parameters $y_{CP}^{\pi\pi} - y_{CP}^{K\pi}$ and $y_{CP}^{KK} - y_{CP}^{K\pi}$, and are measured as $y_{CP}^{\pi\pi} - y_{CP}^{K\pi} = (6.57 \pm 0.53 \pm 0.16) \times 10^{-3}$, $y_{CP}^{KK} - y_{CP}^{K\pi} = (7.08 \pm 0.30 \pm 0.14) \times 10^{-3}$, where the first uncertainties are statistical and the second systematic. The combination of the two measurements is $y_{CP} - y_{CP}^{K\pi} = (6.96 \pm 0.26 \pm 0.13) \times 10^{-3}$, which is four times more precise than the previous world average

Nuclear modification factor of neutral pions in the forward and backward regions in ppPb collisions

The nuclear modification factor of neutral pions is measured in proton-lead collisions collected at a center-of-mass energy per nucleon of $8.16$ TeV with the LHCb detector. The $\pi^0$ production cross section is measured differentially in transverse momentum ($p_{T}$) for 1.5π0 production cross section is measured differentially in transverse momentum (pT) for 1.5<pT<10.0  GeV and in center-of-mass pseudorapidity (ηc.m.) regions 2.5<ηc.m.<3.5 (forward) and -4.0<ηc.m.<-3.0 (backward) defined relative to the proton beam direction. The forward measurement shows a sizable suppression of π0 production, while the backward measurement shows the first evidence of π0 enhancement in proton-lead collisions at the LHC. Together, these measurements provide precise constraints on models of nuclear structure and particle production in high-energy nuclear collisions.The nuclear modification factor of neutral pions is measured in proton-lead collisions collected at a center-of-mass energy per nucleon of 8.16~{\rm TeV}$with the LHCb detector. The$\pi^0$production cross section is measured differentially in transverse momentum ($p_{\rm T}$) for$1.5<p_{\rm T}<10.0~{\rm GeV}$and in center-of-mass pseudorapidity ($\eta_{\rm c.m.}$) regions$2.5<\eta_{\rm c.m.}<3.5$(forward) and$-4.0<\eta_{\rm c.m.}<-3.0$(backward) defined relative to the proton beam direction. The forward measurement shows a sizable suppression of$\pi^0$production, while the backward measurement shows the first evidence of$\pi^0$ enhancement in proton-lead collisions at the LHC. Together, these measurements provide precise constraints on models of nuclear structure and particle production in high-energy nuclear collisions