Broadband photodetectors (PDs) are essential for various applications, including optical communication, sensing, and imaging. Modern semiconductor PD technologies often face challenges related to spectral coverage, power consumption, complex manufacturing, and limited integration with silicon electronics. As photonics technologies continue to advance alongside growing performance demands, exploring new avenues for innovative, cost-effective broadband PDs with reduced power consumption and manufacturing complexity is becoming increasingly important. In this work, we present a zero-bias, waveguide-integrated PD based on single-layer MoS₂, which operates at telecom wavelengths with no dark current. By utilizing the photothermoelectric effect combined with internal photoemission process, our devices demonstrate a record responsivity of ∼180 V/W at 1550 nm, the highest reported in the literature for unbiased 2D PDs operating in the short-wave infrared. The recorded frequency response is in the millisecond range, limited by the electrical RC time constant. The PD noise equivalent power is ∼500 nW at 1 Hz, dominated by 1/f noise, and is reduced to ∼0.3 nW at the Johnson limit. Consequently, the specific detectivity (D*) is estimated to be ∼10⁵ Jones at the 1/f limit, reaching ∼2 × 10¹⁰ Jones at Johnson noise-limited operation. Our findings contribute to developing high-efficiency broadband MoS₂ PDs and emphasize the potential of 2D semiconductors in advancing self-powered PDs technology.

Engineering ferroelectric interfaces is key to improving device performance. Combining thin insulators with ferroelectrics is a promising approach for minimizing leakage currents and increasing the switching efficiency. In this work, we study the interface between atomic layer deposited amorphous Al₂O₃ and epitaxial BaTiO₃ films. These materials constitute simple and robust examples of an insulator and a ferroelectric, respectively. We confirm the microstructure and interface chemistry of the heterostructure. X-ray photoelectron spectroscopy was employed to quantify the interfacial band offsets, yielding energy barriers of 1.3 eV for holes and 2.1 eV for electrons. These results highlight Al₂O₃ as a promising candidate for an insulating layer on ferroelectrics, paving the way for efficient insulator-ferroelectrics structures for ferroelectric functional devices.

We present controlled interplay between the surface second-order and bulk third-order nonlinearities of gold, utilizing wave mixing between surface plasmons on the metal-air interface and free-space photons. By tuning the nonlinear interactions, we demonstrate experimentally that photons emerging from these inherently different mechanisms can interfere, while both their relative amplitude and phase are controlled solely by the pump beam. These results provide a foundation for engineering plasmonic nonlinearities and open new possibilities for quantum photonic applications.

The weak interlayer binding in two-dimensional layered materials such as graphite has been the subject of intensive experimental investigation and modeling for structural superlubric and electronic devices. Yet, the effects of sliding velocity and temperature on the interfacial lateral forces in mesoscale contacts are poorly understood. Here, we report experiments of friction and adhesion forces in atomically pristine mesoscopic superlubric graphite, conducted over a range of sliding velocities and temperatures. It is shown that the friction force, temperature, and velocity follow the linear correlation of ${(F_c-F)}^{3/2}/T$ vs $\text{ln}(v/T)$ ⁠, which intriguingly aligns well with the thermally activated Prandtl–Tomlinson model associated with single asperity contacts. Moreover, when the velocity is lower than 2500 nm/s and the friction force approaches zero, the adhesive force increases with velocity and decreases with increasing temperature, indicating a thermally activated exfoliation process. Our results demonstrate that in cases where the interface is constrained to be atomically flat, mesoscale contacts can manifest single asperity force characteristics, where the sliding interface is collectively affected by thermal energy.

Using ultrafast dual-frequency two-dimensional infrared spectroscopy (DF-2DIR), we probed how the strong coupling of high-frequency molecular vibrations to surface lattice resonances of infrared antennas, which act as a photonic cavity, affects intramolecular vibrational relaxation (IVR). DF-2DIR allows one to probe the IVR pathways beyond the vibrational state subspace of the polaritons and reservoir states, which is typically accessed in conventional 2DIR experiments. We observed anharmonic coupling between lower polariton and high-frequency molecular vibrational modes not coupled to the cavity directly, which appeared in the strongly coupled system by virtue of the polariton’s molecular component, and alternation of the rate of excitation energy excess transfer from the polariton to a distant molecular vibrational mode, which depended on the polariton transition frequency. These are in contrast with the weak coupling regime, where enhanced fields magnify molecular vibrational signals without affecting their dynamics. Our work demonstrates a promising experimental approach toward understanding of polariton chemistry phenomena.

Electrochemical random-access memory (ECRAM) devices are a promising candidate for neuromorphic computing, as they mimic synaptic functions by modulating conductance through ion migration. However, the use of a thick electrolyte layer (>40 nm) in conventional ECRAMs leads to an unavoidable tradeoff between synaptic weight updates and operating speed. To address this problem, a Cu-based ultrathin ECRAM (UT-ECRAM) that uses a single 5 nm HfO_x active layer and a ≈1.2 nm AlO_x liner is designed. The highly efficient gate-tunable fast Cu-ion transport in the AlO_x/HfO_x UT-ECRAM enables 1) near-ideal linearity in weight updates (0.45) even achieved with a pulse width (t_w) of 50 μs, 2) dynamic multilevel retention of 10⁴ s, and 3) reliable cycling endurance of 10⁴ cycles. A numerical analysis based on device scaling quantitatively reveals that a relatively high concentration of field-driven Cu ions (≈10²⁰ cm⁻³) contributes to each synaptic weight update per gate voltage (V_G) pulse in the UT-ECRAM without becoming deactivated by traversing thicker layers. This improved gate sensitivity can ultimately overcome the linearity and the ratio/speed tradeoff relationships, paving the way for robust neuromorphic synaptic units.

Two-dimensional (2D) semiconductors are promising for photonic applications due to their exceptional optoelectronic properties, including large exciton binding energy, strong spin–orbit coupling, and potential integration with the standard complementary silicon-oxide-semiconductor (CMOS) technology. The dielectric environment can significantly affect the photoluminescence (PL) spectra of transition metal dichalcogenide (TMD) monolayers by modulating excitonic properties such as optical transitions and binding energies. Specifically, substrates with higher dielectric permittivity reduce exciton binding energy and the quasiparticle bandgap. Doping and the charge carrier concentration can further modify the emitted spectra by affecting the PL excitonic content. Increased doping can enhance trion formation and bandgap renormalization phenomena, leading to PL spectral shifts that depend on the semiconductor type. This study systematically investigates the substrate-induced dielectric screening, doping, and trapped charges in CVD-grown n-type 1L-WS₂ and p-type 1L-WSe₂ transferred onto CMOS-relevant SiO₂ and HfO₂ dielectrics. Our results show that p-type 1L-WSe₂ exhibits higher PL intensity and red-shifted trion emission on HfO₂, whereas n-type 1L-WS₂ shows a blue-shifted, lower-intensity PL for a similar dielectric environment. The difference arises from the interplay of the semiconductor type, doping, dielectric screening, and charge carrier concentration. We demonstrate that suspending the monolayers at the nanoscale enhances PL by reducing nonradiative recombination, enabling controlled micro-PL patterning and the formation of localized emission hot spots. Our results provide valuable insights for the development of next-generation CMOS-compatible optoelectronic devices.

Conventional FeRAM readout methods are destructive, requiring polarization switching of the FE capacitor (FeCAP) and write-back, which reduces endurance, increases latency, and energy consumption. Prior works on non-destructive readout (NDRO) relied on capacitance memory window (MW), which is slow and requires asymmetric FeCAP structure, compromising retention and increasing circuit complexity. Here, we present a novel NDRO method utilizing ultrafast transient response which applies to both symmetric and asymmetric structures. We experimentally demonstrate sub-ns read operations without altering the polarization state, achieving >10¹³ read cycles (limited by test time). This structure-agnostic method improves retention (tested at 125°C), endurance, and simplifies implementation, thus paving the way for fast, energy-efficient FeRAM-based solutions.

We demonstrate Andreev pair injection across Nb-WS₂ junction evident as Andreev reflection in differential conductivity spectra below Nb critical temperature \({T}_{c}\). The superconducting- 2D semiconducting junction defined by a focused ion beam, shaped Nb pads, and semi-dry transfer of single layer CVD-grown WS₂ crystals ensured the mechanical integrity of the 2D TMD film, reduced contamination and defects at Nb-WS₂ junction, enabling the pristine study of the interface and facilitating Andreev pair injection. We observed enhanced conductivity in \({dI}/{dV}\) spectra for junction voltages smaller than the corresponding Nb superconducting gap, which vanishes as the device temperature is increased above the \({T}_{c}\). The position and the temperature dependence of the conductivity peaks suggest proximity effect-related phenomena explained by developed modified BTK theory. The presented results are crucial for the future implementation of proximity-based 2D hybrid devices including quantum light sources and superconducting field-effect transistors based on superconductor-semiconductor junctions.

Quantum nanophotonics offers essential tools and technologies for controlling quantum states, while maintaining a miniature form factor and high scalability. For example, nanophotonic platforms can transfer information from the traditional degrees of freedom (DoFs), such as spin angular momentum (SAM) and orbital angular momentum (OAM), to the DoFs of the nanophotonic platform - and back, opening new directions for quantum information processing. Recent experiments have utilized the total angular momentum (TAM) of a photon as a unique means to produce entangled qubits in nanophotonic platforms. Yet, the process of transferring the information between the free-space DoFs and the TAM was never investigated, and its implications are still unknown. Here, we reveal the evolution of quantum information in heralded single photons as they couple into and out of the near-field of a nanophotonic system. Through quantum state tomography, we discover that the TAM qubit in the near-field becomes a free-space qudit entangled in the photonic SAM and OAM. The extracted density matrix and Wigner function in free-space indicate state preparation fidelity above 97%. The concepts described here bring new concepts and methodologies in developing high-dimensional quantum circuitry on a chip.