Polarizers provide convenience in generating polarized light, meanwhile their adoption raises problems of extra weight, cost, and energy loss. Aiming to realize polarizer-free polarized light sources, herein, we present a plasmonic approach to achieve direct generation of linearly polarized optical waves at the nanometer scale. Periodic slot nanoantenna arrays are fabricated, which are driven by the transition dipole moments of luminescent semiconductor quantum dots. By harnessing interactions between quantum dots and scattered fields from the nanoantennas, spontaneous emission with a high degree of linear polarization is achieved from such hybrid antenna system with polarization perpendicular to antenna slot. We also demonstrate that the polarization is engineerable in aspects of both spectrum and magnitude by tailoring plasmonic resonance of the antenna arrays. Our findings will establish a basis for the development of innovative polarized light-emitting devices, which are useful in optical displays, spectroscopic techniques, optical telecommunications, and so forth.

Transition-metal dichalcogenides are promising challengers to conventional semiconductors owing to their remarkable electrical performance and suppression of shortchannel effects (SCEs). In particular, monolayer molybdenum disulfide has exhibited superior suppression of SCEs owing to its atomic thickness, high effective carrier mass, and low dielectric constant. However, difficulties still remain in largescale stable fabrication of nanometer-scale channels. Herein, a method to fabricate electrodes with sub-10 nm gaps was demonstrated using horizontally aligned single-walled carbon nanotubes as an evaporation mask. The widths of the nanogaps exhibit robust stability to various process parameters according to the statistical results. Based on these nanogaps, ultrashort-channel length monolayer MoS 2 field-effect transistors were produced. Monolayer MoS 2 devices with a 7.5 nm channel length and a 10 nm thick HfO 2 dielectric layer exhibited excellent performances with an ON/OFF ratio up to 10 7 , a mobility of 17.4 cm 2 /V•s, a subthreshold swing of about 120 mV/dec, and a drain-induced barrier lowering of about 140 mV/V, all of which suggest a superior suppression of SCEs. This work provides a universal and stable method for large-scale fabrication of ultrashort-channel 2D-material transistors.

We introduce a simple and cost-effective approach for fabrication of effective surface-enhanced Raman spectroscopy (SERS) substrates. It is shown that the as-fabricated substrates show excellent SERS effects in various probe molecules with high sensitivity, that is, picomolar level detection, and also good reliability. With a SERS enhancement factor beyond 10 and excellent reproducibility (deviation less than 5%) of signal intensity, the fabrication of the SERS substrate is realized on a four-inch wafer and proven to be effective in pesticide residue detection. The SERS substrate is realized first through the fabrication of quasi-periodic nanostructured silicon with dimension features in tens of nanometers using superaligned carbon nanotubes networks as an etching mask, after which a large amount of hot spots with nanometer gaps are formed through deposition of a gold film. With rigorous nanostructure design, the enhanced performance of electromagnetic field distribution for nanostructures is optimized. With the advantage of cost-effective large-area preparation, it is believed that the as-fabricated SERS substrate could be used in a wide variety of actual applications where detection of trace amounts is necessary.