Irradiation of Nanostrained Monolayer WSe2_2 for Site-Controlled Single-Photon Emission up to 150 K

Quantum-dot-like WSe$_2$ single-photon emitters have become a promising platform for future on-chip scalable quantum light sources with unique advantages over existing technologies, notably the potential for site-specific engineering. However, the required cryogenic temperatures for the functionality of these sources have been an inhibitor of their full potential. Existing strain engineering methods face fundamental challenges in extending the working temperature while maintaining the emitter's fabrication yield and purity. In this work, we demonstrate a novel method of designing site-specific single-photon emitters in atomically thin WSe$_2$ with near-unity yield utilizing independent and simultaneous strain engineering via nanoscale stressors and defect engineering via electron-beam irradiation. Many of these emitters exhibit exciton-biexciton cascaded emission, purities above 95%, and working temperatures extending up to 150 K, which is the highest observed in van der Waals semiconductor single-photon emitters without Purcell enhancement. This methodology, coupled with possible plasmonic or optical micro-cavity integration, potentially furthers the realization of future scalable, room-temperature, and high-quality van der Waals quantum light sources

Cavity-Enhanced 2D Material Quantum Emitters Deterministically Integrated with Silicon Nitride Microresonators

Optically active defects in 2D materials, such as hexagonal boron nitride (hBN) and transition metal dichalcogenides (TMDs), are an attractive class of single-photon emitters with high brightness, room-temperature operation, site-specific engineering of emitter arrays, and tunability with external strain and electric fields. In this work, we demonstrate a novel approach to precisely align and embed hBN and TMDs within background-free silicon nitride microring resonators. Through the Purcell effect, high-purity hBN emitters exhibit a cavity-enhanced spectral coupling efficiency up to $46\%$ at room temperature, which exceeds the theoretical limit for cavity-free waveguide-emitter coupling and previous demonstrations by nearly an order-of-magnitude. The devices are fabricated with a CMOS-compatible process and exhibit no degradation of the 2D material optical properties, robustness to thermal annealing, and 100 nm positioning accuracy of quantum emitters within single-mode waveguides, opening a path for scalable quantum photonic chips with on-demand single-photon sources

A mode-balanced reconfigurable logic gate built in a van der Waals strata

Abstract: Two-dimensional (2D) semiconducting materials, in particular transition-metal dichalcogenides, have emerged as the preferred channel materials for sub-5 nm field-effect transistors (FETs). However, the lack of practical doping techniques for these materials poses a significant challenge to designing complementary logic gates containing both n- and p-type FETs. Although electrical tuning of the polarity of 2D-FETs can potentially circumvent this problem, such devices suffer from the lack of balanced n- and p-mode transistor performance, forming one of the most enigmatic challenges of the reconfigurable 2D-FET technology. Here we provide a solution to this dilemma by judicious use of van der Waals (vdW) materials consisting of conductors, dielectrics and semiconductors forming a 50 nm thin quantum engineered strata that can guarantee a purely vdW-type interlayer interaction, which faithfully preserves the mid-gap contact design and thereby achieves an intrinsically mode-balanced and fully reconfigurable all-2D logic gate. The intrinsically mode-balanced gate eliminates the need for transistor sizing and allows post-fabrication reconfigurability to the transistor operation mode, simultaneously allowing an ultra-compact footprint and increased circuit functionality, which can be potentially exploited to build more area-efficient and low-cost integrated electronics for the internet of things (IoT) paradigm

Defect and strain engineering of monolayer WSe2 enables site-controlled single-photon emission up to 150 K

Quantum defects in 2D semiconductors are promising quantum light sources, but the required cryogenic temperatures limit their applicability. Here, the authors report a method to create single-photon emitters in monolayer WSe2 operating at temperatures up to 150 K without plasmonic or optical cavities