Atomic Layer Deposition of ZnO on Multi-walled Carbon Nanotubes and Its Use for Synthesis of CNT–ZnO Heterostructures

In this article, direct coating of ZnO on PECVD-grown multi-walled carbon nanotubes (MWCNTs) is achieved using atomic layer deposition (ALD). Transmission electron microscopy investigation shows that the deposited ZnO shell is continuous and uniform, in contrast to the previously reported particle morphology. The ZnO layer has a good crystalline quality as indicated by Raman and photoluminescence (PL) measurements. We also show that such ZnO layer can be used as seed layer for subsequent hydrothermal growth of ZnO nanorods, resulting in branched CNT–inorganic hybrid nanostructures. Potentially, this method can also apply to the fabrication of ZnO-based hybrid nanostructures on other carbon nanomaterials

Self-Limiting Layer Synthesis of Transition Metal Dichalcogenides

This work reports the self-limiting synthesis of an atomically thin, two dimensional transition metal dichalcogenides (2D TMDCs) in the form of MoS2. The layer controllability and large area uniformity essential for electronic and optical device applications is achieved through atomic layer deposition in what is named self-limiting layer synthesis (SLS); a process in which the number of layers is determined by temperature rather than process cycles due to the chemically inactive nature of 2D MoS2. Through spectroscopic and microscopic investigation it is demonstrated that SLS is capable of producing MoS2 with a wafer-scale (similar to 10 cm) layer-number uniformity of more than 90%, which when used as the active layer in a top-gated field-effect transistor, produces an on/off ratio as high as 10(8). This process is also shown to be applicable to WSe2, with a PN diode fabricated from a MoS2/WSe2 heterostructure exhibiting gate-tunable rectifying characteristics.ope

Integrated sensitive on-chip ion field effect transistors based on wrinkled InGaAs nanomembranes

Self-organized wrinkling of pre-strained nanomembranes into nanochannels is used to fabricate a fully integrated nanofluidic device for the development of ion field effect transistors (IFETs). Constrained by the structure and shape of the membrane, the deterministic wrinkling process leads to a versatile variation of channel types such as straight two-way channels, three-way branched channels, or even four-way intersection channels. The fabrication of straight channels is well controllable and offers the opportunity to integrate multiple IFET devices into a single chip. Thus, several IFETs are fabricated on a single chip using a III-V semiconductor substrate to control the ion separation and to measure the ion current of a diluted potassium chloride electrolyte solution

Examining the role of genetic risk and longitudinal transmission processes underlying maternal parenting and psychopathology and children’s ADHD symptoms and aggression: utilizing the advantages of a prospective adoption design

Although genetic factors may contribute to initial liability for ADHD onset, there is growing evidence of the potential importance of the rearing environment on the developmental course of ADHD symptomatology. However, associations between family-level variables (maternal hostility, maternal depressive symptoms) and child behaviors (developmental course of ADHD and aggression) may be explained by genes that are shared by biologically related parents and children. Furthermore, ADHD symptoms and aggression commonly co-occur: it is important to consider both simultaneously to have a better understanding of processes underlying the developmental course of ADHD and aggression. To addresses these issues, we employed a longitudinal genetically sensitive parent–offspring adoption design. Analyses were conducted using Cohort I (n = 340) of the Early Growth and Development Study with cross-validation analyses conducted with Cohort II (n = 178). Adoptive mother hostility, but not depression, was associated with later child ADHD symptoms and aggression. Mothers and their adopted children were genetically unrelated, removing passive rGE as a possible explanation. Early child impulsivity/activation was associated with later ADHD symptoms and aggression. Child impulsivity/activation was also associated with maternal hostility, with some evidence for evocative gene-environment correlation processes on adoptive mother depressive symptoms. This study provides novel insights into family-based environmental influences on child ADHD and aggression symptoms, independent of shared parental genetic factors, implications of which are further explicated in the discussion

High-Rate Spinel LiMn<inf>2</inf>O<inf>4</inf> (LMO) following Carbonate Removal and Formation of Li-Rich Interface by ALD Treatment

Recent work has identified enhanced charge-storage capacity in the spinel lithium manganese oxide (LiMn2O4; LMO) lithium-ion battery cathode upon a single atomic layer deposition (ALD) cycle composed of one chemical exposure of trimethylaluminum (TMA) and one exposure of water (H2O). Here, we report further study of the rate capability following one TMA/H2O exposure and identify enhanced rate capability versus pristine LMO. To understand this effect, we experimentally probe the surface composition of LMO with TMA/H2O treatment using X-ray photoelectron spectroscopy measurements with inert transfer. This includes a study of the LMO surface properties following TMA exposure before exposure to H2O. We identify the removal of a surface carbonate layer from LMO upon TMA exposure and the formation of a Li-rich aluminum oxide surface layer upon subsequent H2O exposure. We also observe a previously undescribed phenomenon of Li ions depleting from the LMO surface upon TMA exposure and returning upon H2O exposure. These effects are connected with the enhanced rate capability of ALD-coated LMO and are related to a range of emerging studies on carbonate surface layers in battery cathodes, as well as the use of ALD to stabilize battery interfaces