Doron Naveh

Tunable band gaps in bilayer graphene-BN heterostructures.

We investigate band gap tuning of bilayer graphene between hexagonal boron nitride sheets, by external electric fields. Using density functional theory, we show that the gap is continuously tunable from 0 to 0.2 eV and is robust to stacking disorder. Moreover, boron nitride sheets do not alter the fundamental response from that of free-standing bilayer graphene, apart from additional screening. The calculations suggest that graphene-boron nitride heterostructures could provide a viable route to graphene-based electronic devices.

Strain-driven light-polarization switching in deep ultraviolet nitride emitters

Residual strain plays a critical role in determining the crystalline quality of nitride epitaxial layers and in modifying their band structure; this often leads to several interesting physical phenomena. It is found, for example, that compressive strain in AlxGa1-xN layers grown on AlyGa1-yN (x<y) templates results in an anti-crossing of the valence bands at considerably much higher Al composition than expected. This happens even in the presence of large and negative crystal field splitting energy for AlxGa1-xN layers. A judicious magnitude of the compressive strain can support vertical light emission (out of the c-plane) from AlxGa1-xN quantum wells up to x\approx 0.80, which is desirable for the development of deep ultraviolet light-emitting diodes designed to operate below 250nm with transverse electric polarization characteristics.

Widely tunable black phosphorus mid-infrared photodetector

Lately rediscovered orthorhombic black phosphorus (BP) exhibits promising properties for near- and mid-infrared optoelectronics. Although recent electrical measurements indicate that a vertical electric field can effectively reduce its transport bandgap, the impact of the electric field on light-matter interaction remains unclear. Here we show that a vertical electric field can dynamically extend the photoresponse in a 5 nm-thick BP photodetector from 3.7 to beyond 7.7 μm, leveraging the Stark effect. We further demonstrate that such a widely tunable BP photodetector exhibits a peak extrinsic photo-responsivity of 518, 30, and 2.2 mA W−1 at 3.4, 5, and 7.7 μm, respectively, at 77 K. Furthermore, the extracted photo-carrier lifetime indicates a potential operational speed of 1.3 GHz. Our work not only demonstrates the potential of BP as an alternative mid-infrared material with broad optical tunability but also may enable the compact, integrated on-chip high-speed mid-infrared photodetectors, modulators, and spectrometers.The bandgap of ultrathin black phosphorus can be tuned by a vertical electric field. Here, the authors leverage such electric field to extend the photoresponse of a black phosphorus photodetector to 7.7 μm, opening the doors to various mid-infrared applications.

Protective molecular passivation of black phosphorus

Black phosphorus is a fascinating layered material, with extraordinary anisotropic mechanical, optical and electronic properties. However, the sensitivity of black phosphorus to oxygen and moisture poses significant challenges for technological applications of this unique material. Here, we report a viable solution that overcomes degradation of few-layer black phosphorus by passivating the surface with self-assembled monolayers of octadecyltrichlorosilane that provide long-term stability in ambient conditions. Importantly, we show that this treatment does not cause any undesired carrier doping of the bulk channel material, thanks to the emergent hierarchical interface structure. Our approach is compatible with conventional electronic materials processing technologies thus providing an immediate route toward practical applications in black phosphorus devices.Making black phosphorus airtightBlack phosphorus is a leading contender among new semiconductors for nanoscale optoelectronics, but its use is impeded by rapid degradation in air. A team of Israeli and US scientists, led by Doron Naveh from Bar Ilan University, has devised an inexpensive and scalable approach for long-term stabilization of black phosphorus, bringing it one step closer to real-world applications. By treating black phosphorus with octadecyltrichlorosilane (OTS), a chemical commonly used in semiconductor processing, Naveh and coworkers were able to produce self-assembled polymer coatings that protect black phosphorus from oxygen and moisture. Importantly, this chemical treatment does not alter the overall electronic properties of black phosphorus nor does it complicate subsequent device fabrication. With this advance, researchers can now stabilize and study black phosphorus devices with relative ease under normal operating conditions.

Raman scattering and electrical resistance of highly disordered graphene

Raman scattering (RS) spectra and current-voltage characteristics at room temperature were measured in six series of small samples fabricated by means of electron-beam lithography on the surface of a large size

Localization of Charge Carriers in Monolayer Graphene Gradually Disordered by Ion Irradiation

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Air-Stable Room-Temperature Mid-Infrared Photodetectors Based on hBN/Black Arsenic Phosphorus/hBN Heterostructures

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On the impact of Vertical Alignment of MoS 2 for Efficient Lithium Storage

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Combining 2D inorganic semiconductors and organic polymers at the frontier of the hard–soft materials interface

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Lithographically Patterned Functional Polymer–Graphene Hybrids for Nanoscale Electronics

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