Two-dimensional transition metal dichalcogenides (TMDCs) have natural advantages in overcoming the short-channel effect in field-effect transistors (FETs) and in fabricating three-dimensional FETs, which benefit in increasing device density. However, so far, most reported works related to MoS2 FETs with a sub-100 nm channel employ mechanically exfoliated materials and all of the works involve electron beam lithography (EBL), which may limit their application in fabricating wafer-scale device arrays as demanded in integrated circuits (ICs). In this work, MoS2 FET arrays with a side-wall source and drain electrodes vertically distributed are designed and fabricated. The channel length of the as-fabricated FET is basically determined by the thickness of an insulating layer between the source and drain electrodes. The vertically distributed source and drain electrodes enable to reduce the electrode-occupied area and increase in the device density. The as-fabricated vertical FETs exhibit on/off ratios comparable to those of mechanically exfoliated MoS2 FETs with a nanoscale channel length under identical VDS. In addition, the as-fabricated FETs can work at a VDS as low as 10 mV with a desirable on/off ratio (1.9 × 107), which benefits in developing low-power devices. Moreover, the fabrication process is free from EBL and can be applied to wafer-scale device arrays. The statistical results show that the fabricated FET arrays have a device yield of 87.5% and an average on/off ratio of about 1.7 × 106 at a VDS of 10 mV, with the lowest and highest ones to be about 1.3 × 104 and 1.9 × 107, respectively, demonstrating the good reliability of our fabrication process. Our work promises a bright future for TMDCs in realizing high-density and low-power nanoelectronic devices in ICs.
High-purity scandium oxide is the principal raw material of high-purity scandium metal and aluminum scandium alloy targets for electronic materials. The performance of electronic materials will be significantly impacted by the presence of trace amounts of radionuclides due to the increase in free electrons. However, about 10 ppm of Th and 0.5-20 ppm of U are typically present in commercially available high-purity scandium oxide, which it is highly necessary to remove. It is currently challenging to detect trace impurities in high-purity scandium oxide, and the detection range of trace thorium and uranium is relatively high. Therefore, it is crucial to develop a technique that can accurately detect trace Th and U in high concentrations of scandium solution in the research on high-purity scandium oxide quality detection and the removal of trace impurities. This paper adopted some advantageous initiatives to develop a method for the inductively coupled plasma optical emission spectrometry (ICP-OES) determination of Th and U in high-concentration scandium solutions, such as spectral line selection, matrix influence analysis, and spiked recovery. The reliability of the method was verified. The relative standard deviations (RSD) of Th is less than 0.4%, and the RSD of U is less than 3%, indicating that this method has good stability and high precision. This method can be used for the accurate determination of trace Th and U in high Sc matrix samples, which provides an effective technical support for the preparation of high purity scandium oxide, and supports the production of high-purity scandium oxide.
Two-dimensional magnetic semiconductors provide a platform for studying physical phenomena at atomically thin limit, and promise magneto-optoelectronic devices application. Here, we report light helicity detectors based on graphene-CrI3-graphene vdW heterostructures. We investigate the circularly polarized light excited current and reflective magnetic circular dichroism (RMCD) under various magnetic fields in both monolayer and multilayer CrI3 devices. The devices exhibit clear helicity-selective photoresponse behavior determined by the magnetic state of CrI3. We also find abnormal negative photocurrents at higher bias in both monolayer and multilayer CrI3. A possible explanation is proposed for this phenomenon. Our work reveals the interplay between magnetic and optoelectronic properties in CrI3 and paves the way to developing spin-optoelectronic devices.
The widespread dissemination of policy information is necessary for the success of the public policy, but the distribution of information among vulnerable groups has received little attention. We examined a public policy that focuses on the poorest people in China, the anti-poverty relocation and settlement program (ARSP). The infrastructure in the region where the policy is implemented is weak, and the information literacy of resettlers is low. This study analyses the impact of the policy information gap on the subjective well-being of resettlers. We found that the distribution of policy information among the poor is uneven, and the resettlers compare the policy information they obtain with a reference group (working-age people and less-educated people in the same village/community) to generate a policy information gap. The policy information gap indirectly affects subjective well-being by affecting the probability that people will be exposed to risks due to policy. As the policy information gap increases, the subjective well-being of resettlers changes in an inverted U-shape. This impact varies significantly among different groups, policy implementation stages, and resettlement methods. Attention should be paid to the information acquisition ability of the vulnerable groups and the welfare effects of social comparison, and to improve the method of publicizing policy information, which helps to improve the well-being of resettlers.
Emigrants and Immigrants , Public Policy , Social Welfare , Adult , China , Female , Humans , Male , Middle Aged , Poverty
