Phase-change materials (PCMs) offer a compelling platform for active metaoptics, owing to their large index contrast and fast yet stable phase transition attributes. Despite recent advances in phase-change metasurfaces, fully integrable solution that combines pronounced tuning measures, i.e., efficiency, dynamic range, speed, power consumption, is still elusive. Here, we demonstrate an situ electrically driven tunable metasurface by harnessing the full potential of PCM alloy, Ge2Sb2Te5...

Reconfiguration of silicon photonic integrated circuits relying on the weak, volatile thermo-optic or electro-optic effect usually suffers from a large footprint and energy consumption. Here, integrating phase-change material, Ge2Sb2Te5 (GST) with microring resonators, we demonstrate an energy-efficient, compact, non-volatile, reprogrammable platform. By adjusting number free-space laser pulses applied to GST, characterize strong broadband attenuation optical phase modulation effects...

Reconfigurability of photonic integrated circuits (PICs) has become increasingly important due to the growing demands for electronic-photonic systems on a chip driven by emerging applications, including neuromorphic computing, quantum information, and microwave photonics. Success in these fields usually requires highly scalable switching units as essential building blocks. Current switches, however, mainly rely materials with weak, volatile thermo-optic or electro-optic modulation effects,...

Heterogeneous integration of nanomaterials has enabled advanced electronics and photonics applications. However, similar progress been challenging for thermal applications, in part due to shorter wavelengths heat carriers (phonons) compared electrons photons. Here, we demonstrate unusually high isolation across ultrathin heterostructures, achieved by layering atomically thin two-dimensional (2D) materials. We realize artificial stacks monolayer graphene, MoS2, WSe2 with resistance greater...

Efficient hybrid plasmonic-photonic metasurfaces that simultaneously take advantage of the potential both pure metallic and all-dielectric nanoantennas are identified as an emerging technology in flat optics. Nevertheless, post-fabrication tunable still elusive. Here, we present a reconfigurable metasurface platform by incorporating phase-change material Ge$_{2}$Sb$_{2}$Te$_{5}$ (GST) into metal-dielectric meta-atoms for active non-volatile tuning properties light. We systematically design...

Metal contacts are a key limiter to the electronic performance of two-dimensional (2D) semiconductor devices. Here, we present comprehensive study contact interfaces between seven metals (Y, Sc, Ag, Al, Ti, Au, Ni, with work functions from 3.1 5.2 eV) and monolayer MoS2 grown by chemical vapor deposition. We evaporate thin metal films onto Raman spectroscopy, X-ray photoelectron diffraction, transmission electron microscopy, electrical characterization. uncover that (1) ultrathin oxidized Al...

Resistive random access memory (RRAM) is an important candidate for both digital, high-density data storage and analog, neuromorphic computing. RRAM operation relies on the formation rupture of nanoscale conductive filaments that carry enormous current densities whose behavior lies at heart this technology. Here, we directly measure temperature these in realistic with resolution using scanning thermal microscopy. We use conventional metal ultrathin graphene electrodes, which enable most...

The operation of resistive and phase-change memory (RRAM PCM) is controlled by highly localized self-heating effects, yet detailed studies their temperature are rare due to challenges nanoscale thermometry. Here we show that the combination Raman thermometry scanning thermal microscopy (SThM) can enable such measurements with high spatial resolution. We report temperature-dependent spectra HfO

Two-dimensional (2D) materials have recently been incorporated into resistive memory devices because of their atomically thin nature, but switching mechanism is not yet well understood. Here we study bipolar in MoTe2-based varying thickness and electrode area. Using scanning thermal microscopy (SThM), map the surface temperature under bias, revealing clear evidence localized heating at conductive "plugs" formed during switching. The SThM measurements are correlated to electro-thermal...

Layered materials based on transition-metal dichalcogenides (TMDs) are promising for a wide range of electronic and optoelectronic devices. Realizing such practical applications often requires metal–TMD connections or contacts. Hence, complete understanding band alignments potential barrier heights governing the transport through junctions is critical. However, it presently unclear how energy bands TMD align while in contact with metal as function number layers. In pursuit removing this...

Data storage based on a reversible material phase transition (e.g. amorphous to crystalline) has been studied for nearly five decades. Yet, it was only during the past years that some phase-change memory technologies GeSbTe) have approaching physical scaling limits of smallest possible cell. Here we review recent results from our group and others, which achieved sub-10 nm scale PCM with switching energy single femtojoules per bit. Fundamental could be as low attojoules cubic nanometer...

Nanoscale thermal sensing of devices with calibrated scanning microscopy. The calibration allows converting the electrical response thermo-resistive probes into temperature and considers variable probe-sample exchange processes.

Emerging nonvolatile memories store data by reversible resistive switching in phase-change materials or metal oxides. As memory cell dimensions are reduced to ~10-nm scale below, electrical contacts can dominate the device behavior, yet often poorly understood. Here, we study contact resistance Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sb Te xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> (GST), TiO , and HfO with low-current...

Resistive random access memories (RRAM), based on the formation and rupture of conductive nanoscale filaments, have attracted increased attention for application in neuromorphic in-memory computing. However, this technology is, part, limited by its variability, which originates from stochastic extreme heating filaments. In study, we used scanning thermal microscopy (SThM) to assess effect filament-induced heat spreading surface metal oxide RRAMs with different device designs. We evaluate...

We propose a novel fiducial-free approach for the registration of C-arm fluoroscopy to 3-D ultrasound images prostate brachytherapy implants enable dosimetry. The involves reliable detection subset radioactive seeds from ultrasound, and use needle tracks in both registration. Seed is achieved through template matching radio frequency signals, followed by thresholding spatial filtering. resulting registered complete reconstruction implant multiple views. To compensate deformation caused...

Step junctions are often present in layered materials, i.e. where single-layer regions meet multi-layer regions, yet their effect on thermal transport is not understood to date. Here, we measure heat flow across graphene (GJs) from monolayer bilayer graphene, as well four-layer for the first time, both directions. The conductance of monolayer-bilayer GJ device ranges ~0.5 9.1x10^8 Wm-2K-1 between 50 K 300 K. Atomistic simulations such reveal that layers relatively decoupled, and low...

The effect of strain and oxygen deficiency on the Raman spectrum monoclinic HfO2 is investigated theoretically using first-principles calculations. 1% in-plane compressive applied to a c axes found blue shift phonon frequencies, while tensile does opposite. simulations are compared, good agreement with experimental results frequencies greater than 110 cm−1 for 50 nm thin films. Several modes measured below previously assigned be rotational gases present in air ambient (nitrogen oxygen)....

Triangular barrier has been proposed and implemented for the first time in a punch-through diode based selector by dopant profile engineering. Vertical 4F2 diodes have fabricated on an epitaxial Si stack consists of n+ / i delta-doped p+ (NIPIN) layers low temperature (sub-520°C) epitaxy. We experimentally demonstrate that while conventional NPN selectors exhibit severe sub-threshold slope degradation at high voltage, NIPIN produce ideal subthreshold ~120mV/decade with negligible...

In this paper, we propose a new 2 terminal selection device for STTRAM at 0.6 V, with high on current (>10MA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) and on-off ratio (10 xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ). has recently been proposed as an SRAM alternative fast program erase (0.5-5ns) low voltage (0.2V) high-current (<;20MA/cm [1]. An epitaxial Si NPN structure explored by simulations greater than 1.5V...

The traditional ways of tuning a Silicon photonic network are mainly based on the thermal-optic effect or free carrier silicon. drawbacks these methods volatile nature and extremely small change in complex refractive index (Δn<0.01). In order to achieve low energy consumption smaller footprint for applications such as memories computing, it is essential that two optical states system exhibit high contrast remain non-volatile. Phase materials (PCMs) GST provide solution exhibits drastic...

Recently, we have experimentally demonstrated a bipolar RRAM selector based on punch-through diode using an NPN stack by Si epitaxy (NPN selector). Historically, Metal-Insulator-Metal (MIM) has been promising candidate as due to low processing temperature which may enable back-end compatible stacked RRAM. In this report, present electrical performance comparison of the two technologies. is obtained from calibrated TCAD simulations. A simple Fowler Nordheim (FN) and Direct Tunneling (DT)...

Mos <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is a two-dimensional (2D) semi-conductor which now considered as channel material in 2D FETs [1]-[3]. Recently we found that single-layer (1L) grown by chemical vapour deposition (CVD) and encapsulated with high-quality Al O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> layer exhibit superior performance reliability compared to all previously reported [2]. However, while the <i...

Resistive random access memory (RRAM) is a promising candidate for future non-volatile applications due to its potential performance, scalability and compatibility with CMOS processing. The switching in the RRAM cell occurs via formation of conductive filaments composed sub-stoichiometric oxide (SSO). In this work, we model thermal conduction pair neighboring cells, taking into account more detailed phonon scattering effects SSO than previously considered. We find that devices scaled below...

Resistive memory (RRAM) is a promising technology for high density, non-volatile data storage. Metal-oxide RRAM involves forming and breaking conductive filaments (CF) in an oxide like Hf0 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as the mechanism of CFs are sub-50 nm diameter [1], causing sharp temperature gradients within oxide. However, imaging individual devices challenging due to their nanoscale size presence top electrode...