ABSTRACT
Development of efficient surface passivation methods for semiconductor devices is crucial to counter the degradation in their electrical performance owing to scattering or trapping of carriers in the channels induced by molecular adsorption from the ambient environment. However, conventional dielectric deposition involves the formation of additional interfacial defects associated with broken covalent bonds, resulting in accidental electrostatic doping or enhanced hysteretic behavior. In this study, centimeter-scaled van der Waals passivation of transition metal dichalcogenides (TMDCs) is demonstrated by stacking hydrocarbon (HC) dielectrics onto MoSe2 field-effect transistors (FETs), thereby enhancing the electric performance and stability of the device, accompanied with the suppression of chemical disorder at the HC/TMDCs interface. The stacking of HC onto MoSe2 FETs enhances the carrier mobility of MoSe2 FET by over 50% at the n-branch, and a significant decrease in hysteresis, owing to the screening of molecular adsorption. The electron mobility and hysteresis of the HC/MoSe2 FETs are verified to be nearly intact compared to those of the fabricated HC/MoSe2 FETs after exposure to ambient environment for 3 months. Consequently, the proposed design can act as a model for developing advanced nanoelectronics applications based on layered materials for mass production.
ABSTRACT
A two-dimensional (2D) van der Waals material composed only of tellurium (Te) atoms-tellurene-is drawing attention because of its high intrinsic electrical conductivity and strong interaction with gas molecules, which could allow the development of high-performance chemiresistive sensors. However, the correlation between the morphologies and gas detection properties of tellurene has not yet been studied in depth, and few reports exist on tellurene-based hydrogen sulfide (H2S) chemiresistive sensors in spite of their strong interaction with H2S molecules. Here, we investigate the morphology-dependent H2S gas detection properties of tellurene synthesized using a hydrothermal method. To tailor the morphologies of tellurene, the molecular weight of the surfactant was controlled, revealing that a 1D or 2D form was synthesized and also accompanied with the high crystallinity. The 1D tellurene-based chemiresistive sensor presented superior H2S detection properties compared to the 2D form, achieving a gas response (Rg/Ra) of ~38, even at room temperature. This outstanding performance was attributed to the high intrinsic electrical conductivity and high specific surface area of the resultant 1D tellurene.
ABSTRACT
BACKGROUND AND AIMS: Metabolic syndrome may share the pathophysiology of adipose tissue dysregulation and inadequate immune response with inflammatory bowel disease [IBD]. We determined the association of abdominal obesity [AO] with the risk of developing IBD. METHODS: We conducted a nationwide population-based cohort study using the Korean National Health Insurance Services database. A total of 10 082 568 participants of the 2009 national health screening programme were enrolled. Newly diagnosed Crohn's disease [CD] and ulcerative colitis [UC] were identified using the International Classification of Diseases 10th Revision and specialized national codes for rare intractable diseases. Waist circumference [WC] was classified into six groups and compared with the reference values of 85.0-89.9 cm for men and 80.0-84.9 cm for women. AO was defined as a WC of ≥90 cm for men and ≥85 cm for women. RESULTS: During a median follow-up of 9.3 years, the incidence rates of CD and UC were 2.11 and 8.40 per 100 000 person-years, respectively. After adjustment for age, sex, lifestyle behaviours, income and body mass index [BMI], the increase in baseline WC was significantly associated with the risk of developing CD, but not UC, compared to the references. The risk of developing CD in subjects with AO increased significantly compared to those without AO [adjusted hazard ratio, 1.40; 95% confidence interval, 1.21-1.61], regardless of obesity based on BMI. CONCLUSIONS: Individuals with AO bore an increased risk of developing CD proportional to WC, but not UC, suggesting that visceral adiposity is related to the pathophysiology of CD.