Single-crystalline CdTe nanowire field effect transistors as nanowire-based photodetector

The electronic and photoconductive characteristics of CdTe nanowire-based field effect transistors were studied systematically. The electrical characterization of a single CdTe nanowire FET verifies p-type behavior. The CdTe NW FETs respond to visible-near infrared (400-800 nm) incident light with a fast, reversible and stable response characterized by a high responsivity (81 A W-1), photoconductive gain (similar to 2.5 x 10(4)%) and reasonable response and decay times (0.7 s and 1 s, respectively). These results substantiate the potential of CdTe nanowire-based photodetectors in optoelectronic applications.open112423sciescopu

Overcoming water diffusion limitations in hydrogels via microtubular graphene networks for soft actuators

Hydrogel-based soft actuators can operate in sensitive environments, bridging the gap of rigid machines interacting with soft matter. However, while stimuli-responsive hydrogels can undergo extreme reversible volume changes of up to ~90%, water transport in hydrogel actuators is in general limited by their poroelastic behavior. For poly(N-isopropylacrylamide) (PNIPAM) the actuation performance is even further compromised by the formation of a dense skin layer. Here we show, that incorporating a bioinspired microtube graphene network into a PNIPAM matrix with a total porosity of only 5.4 % dramatically enhances actuation dynamics by up to ~400 % and actuation stress by ~4000 % without sacrificing the mechanical stability, overcoming the water transport limitations. The graphene network provides both untethered light-controlled and electrically-powered actuation. We anticipate that the concept provides a versatile platform for enhancing the functionality of soft matter by combining responsive and two-dimensional materials, paving the way towards designing soft intelligent matter.Comment: Shared First-authorship: Margarethe Hauck and Lena Marie Saur

Molecularly engineered black phosphorus heterostructures with improved ambient stability and enhanced charge carrier mobility

Overcoming the intrinsic instability and preserving unique electronic properties are key challenges for the practical applications of black phosphorus (BP) under ambient conditions. Here, it is demonstrated that molecular heterostructures of BP and hexaazatriphenylene derivatives (BP/HATs) enable improved environmental stability and charge transport properties. The strong interfacial coupling and charge transfer between the HATs and the BP lattice decrease the surface electron density and protect BP sheets from oxidation, resulting in an excellent ambient lifetime of up to 21 d. Importantly, HATs increase the charge scattering time of BP, contributing to an improved carrier mobility of 97 cm2 V-1 s-1, almost three times of the pristine BP films, based on noninvasive THz spectroscopic studies. The film mobility is an order of magnitude larger than previously reported values in exfoliated 2D materials. The strategy opens up new avenues for versatile applications of BP sheets and provides an effective method for tuning the physicochemical properties of other air-sensitive 2D semiconductors

Użycie cyfrowego modelu wysokości (DEM) i systemu informacji geograficznej (GIS) do oceny zasobów wód gruntowych w odniesieniu do form ukształtowania terenu w zlewni Maharlou-Bakhtegan, prowincja Fars w Iranie

The study of groundwater resources in relation to topography is important. Clearly, in different topography, depth of the water level is different. Therefore, the aim of this study is the determination of the relationship between landform classes with compound topographic index (CTI) and depth of the water for the Maharlou- Bakhtegan watershed, Fars Province, Iran. In order to evaluate the depth of the water for the study area, CTI and geomorphology (landforms) were derived from a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). The results of landform classes extracted using topographic position index (TPI) showed that the largest landform is open slope, while the smallest are plains. It was found that CTI and depth of the water values are high in plain classes, while they are low in local ridges. High depth of the water were found to be mostly confined to the pit regions in the plain landform, because groundwater recharge occurs in the zones where standing water remains for sufficient long period of time and has favourable condition for recharge.Badanie zasobów wodnych w stosunku do topografii jest istotne, ponieważ głębokość lustra wody jest różna w warunkach różnego ukształtowania terenu. Dlatego celem przedstawionych badań było ustalenie zależności między różnymi klasami form terenu o złożonym indeksie topograficznym (CTI) a głębokością wody w zlewni Maharlou-Bakhtegan (prowincja Fars, Iran). Do oceny głębokości wody w badanym obszarze pozyskano dane o CTI i geomorfologii z Shuttle Radar Topography Mission (SRTM) cyfrowego modelu wysokości (DEM). W wyniku analizy klas form ukształtowania terenu otrzymanych z użyciem topograficznego indeksu pozycji (TPI) stwierdzono, że największą część zajmowały otwarte stoki, a najmniejszą – równiny. Stwierdzono, że wartości CTI i głębokości wody były duże w klasie równin i niewielkie na lokalnych wzniesieniach. Duże głębokości wody były ograniczone głównie do regionów zagłębień w formach równinnych, ponieważ zasilanie wód podziemnych występuje w strefach, gdzie wody stojące utrzymują się wystarczająco długo i mają sprzyjające warunki do zasilania wód gruntowych

A growth mechanism for free-standing vertical graphene

We propose a detailed mechanism for the growth of vertical graphene by plasma-enhanced vapor deposition. Different steps during growth including nucleation, growth, and completion of the free-standing two-dimensional structures are characterized and analyzed by transmission electron microscopy. The nucleation of vertical graphene growth is either from the buffer layer or from the surface of carbon onions. A continuum model based on the surface diffusion and moving boundary (mass flow) is developed to describe the intermediate states of the steps and the edges of graphene. The experimentally observed convergence tendency of the steps near the top edge can be explained by this model. We also observed the closure of the top edges that can possibly stop the growth. This two-dimensional vertical growth follows a self-nucleated, step-flow mode, explained for the first time.174761sciescopu