A robust valley polarization is a key prerequisite for exploiting valley pseudospin to carry information in next-generation electronics and optoelectronics. Although monolayer transition metal dichalcogenides with inherent spin–valley coupling offer a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time-resolved Kerr rotation spectroscopy, we observe a long-lived valley polarization for positive trion with a lifetime approaching 1 ns at low temperatures, which is much longer than the trion recombination lifetime (∼10–20 ps). The long-lived valley polarization arises from the transfer of valley pseudospin from photocarriers to resident holes in a specific valley. The optically initialized valley pseudospin of holes remains robust even at room temperature, which opens up the possibility to realize room-temperature valleytronics based on transition metal dichalcogenides.

This work describes the synthesis of novel antimicrobial agents consisting of N-halamine and dual quaternary ammonium with different alkyl chain lengths and their antimicrobial applications for PET nonwovens.

The metrology-data-quality-index (DQI y ) algorithm was proposed to perform metrology-data-quality evaluation of the automatic virtual metrology system developed by the authors. The DQI y algorithm is based on the adaptive-resonancetheory 2 (ART2). ART2 divides data into different patterns according to the similarity of process data, and then calculates the corresponding DQI y value and its threshold, DQI yT , for evaluation and judgment. However, in practical applications, the classical ART2 technique still could not cluster process data very precisely. Since some samples with dissimilar process parameters might be sorted into the same cluster, two or more groups could be found in the corresponding metrology-data cluster. This phenomenon may cause invalid DQI y detection. To solve the problem above, the advanced ART2 scheme is proposed in this paper to enhance the accuracy of the DQI y algorithm. A large industrial data-set showing both a shift in metrology measurements without a process shift and a process shift that was not captured by the metrology of the actual photo and color-filter production tools of a TFT-LCD factory were adopted as illustrative examples to verify the practicality of the proposed scheme. Experimental results show that the performance of the advanced ART2 is indeed better than that of the original ART2.Keywords: automatic virtual metrology (AVM); metrology data quality evaluation index (DQI y ); adaptive resonance theory 2 (ART2); single-linkage agglomerative algorithm (SLAA)

InGaN-based light-emitting diodes (LED) with an embedded air-gap disk structure were fabricated using a laser drilling process and an electrochemical (EC) wet etching process. The disk-shaped air-gap structure was formed surrounding the laser-drilled hole as a reflective structure to enhance the light extraction efficiency. The light output power of the treated LED structure was enhanced by 22% compared with a conventional LED at 20 mA. High light emission intensity of the treated LED structure was observed at the 40-µm-diameter embedded air-disk patterns in the mesa region. The InGaN LED structures with the laser-drilling holes and embedded air-disks can reduce the light trapping effect and increase the light extraction efficiency in the device’s central mesa region.