High-refractive-index 2D photonic structures for robust low-threshold multiband lasing.

High-refractive-index (HRI) dielectrics are gaining increasing attention as building blocks for compact lasers. Their ability to simultaneously support both electric and magnetic modes provides greater versatility as compared to plasmonic platforms. Moreover, their reduced absorption loss minimizes heat generation, further enhancing their performance.

Deterministic grayscale nanotopography to engineer mobilities in strained MoS FETs.

Field-effect transistors (FETs) based on two-dimensional materials (2DMs) with atomically thin channels have emerged as a promising platform for beyond-silicon electronics. However, low carrier mobility in 2DM transistors driven by phonon scattering remains a critical challenge. To address this issue, we propose the controlled introduction of localized tensile strain as an effective means to inhibit electron-phonon scattering in 2DM.

Combining thermal scanning probe lithography and dry etching for grayscale nanopattern amplification.

Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and fluidics. Thermal scanning probe lithography achieves a lateral resolution below 10 nm and a vertical resolution below 1 nm, but its maximum depth in polymers is limited. Here, we present an innovative combination of nanowriting in thermal resist and plasma dry etching with substrate cooling, which achieves up to 10-fold amplification of polymer nanopatterns into SiO without proportionally increasing surface roughness.

Edge-Contact MoS Transistors Fabricated Using Thermal Scanning Probe Lithography.

The science and engineering of two-dimensional materials (2DMs), in particular, of 2D semiconductors, is advancing at a thriving pace. It is well known that these delicate few-atoms thick materials can be damaged during the processing toward their integration into final devices. Thermal scanning probe lithography (t-SPL) is a gentle alternative to the typically used electron beam lithography to fabricate these devices avoiding the use of electrons, which are well known to deteriorate the 2DMs' properties.

Thermomechanical Nanostraining of Two-Dimensional Materials.

Local bandgap tuning in two-dimensional (2D) materials is of significant importance for electronic and optoelectronic devices but achieving controllable and reproducible strain engineering at the nanoscale remains a challenge. Here, we report on thermomechanical nanoindentation with a scanning probe to create strain nanopatterns in 2D transition metal dichalcogenides and graphene, enabling arbitrary patterns with a modulated bandgap at a spatial resolution down to 20 nm. The 2D material is in contact via van der Waals interactions with a thin polymer layer underneath that deforms due to the heat and indentation force from the heated probe.

Thermomechanical Nanocutting of 2D Materials.

Atomically thin materials, such as graphene and transition metal dichalcogenides, are promising candidates for future applications in micro/nanodevices and systems. For most applications, functional nanostructures have to be patterned by lithography. Developing lithography techniques for 2D materials is essential for system integration and wafer-scale manufacturing.

Geometric frustration in ordered lattices of plasmonic nanoelements.

Inspired by geometrically frustrated magnetic systems, we present the optical response of three cases of hexagonal lattices of plasmonic nanoelements. All of them were designed using a metal-insulator-metal configuration to enhance absorption of light, with elements in close proximity to exploit near-field coupling, and with triangular symmetry to induce frustration of the dipolar polarization in the gaps between neighboring structures. Both simulations and experimental results demonstrate that these systems behave as perfect absorbers in the visible and/or the near infrared.

Geometric frustration in a hexagonal lattice of plasmonic nanoelements.

We introduce the concept of geometric frustration in plasmonic arrays of nanoelements. In particular, we present the case of a hexagonal lattice of Au nanoasterisks arranged so that the gaps between neighboring elements are small and lead to a strong near-field dipolar coupling. Besides, far-field interactions yield higher-order collective modes around the visible region that follow the translational symmetry of the lattice.

Nanoparticles with tunable shape and composition fabricated by nanoimprint lithography.

Cone-like and empty cup-shaped nanoparticles of noble metals have been demonstrated to provide extraordinary optical properties for use as optical nanoanntenas or nanoresonators. However, their large-scale production is difficult via standard nanofabrication methods. We present a fabrication approach to achieve arrays of nanoparticles with tunable shape and composition by a combination of nanoimprint lithography, hard-mask definition and various forms of metal deposition.