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Heterostructures involving two-dimensional (2D) transition metal dichalcogenides and other materials such as graphene have a strong potential to be the fundamental building block of many electronic and opto-electronic applications. The integration and scalable fabrication of such heterostructures is of essence in unleashing the potential of these materials in new technologies. For the first time, we demonstrate the growth of few-layer MoS2 films on graphene via non-aqueous electrodeposition. Through methods such as scanning and transmission electron microscopy, atomic force microscopy, Raman spectroscopy, energy and wavelength dispersive X-ray spectroscopies and X-ray photoelectron spectroscopy, we show that this deposition method can produce large-area MoS2 films with high quality and uniformity over graphene. We reveal the potential of these heterostructures by measuring the photo-induced current through the film. These results pave the way towards developing the electrodeposition method for the large-scale growth of heterostructures consisting of varying 2D materials for many applications., 11 pages and 6 figures

This paper presents a novel continuously beam-steering dual-band, dual circularly polarized (CP) reflectarray. The dual band operation of the reflectarray is obtained by using the interleaved circularly polarized triangular patches as the radiating elements. Each of the patches has two proximity feed lines that are electromagnetically coupled to a branch line coupler, where the phase shifters are integrated. The phase shifter is realized by using a new type of high-frequency tunable dielectric materials, Lead Niobate Pyrochlores $Pb _{n} Nb _{2}O_{5+ {n}}\,($ PN). By controlling the applied voltage, the dielectric permittivity of the PN material can be changed. This characteristic is utilized to the design of tunable dielectric capacitors, which is placed between the ground and the signal line of a Co-planar waveguide (CPW) transmission line. To validate the design concept, X-band passive antenna prototype was designed, fabricated and measured. Preliminary results on the designed phase shifter and tunable dielectric materials are also presented in this paper.

The identification and optimization of tunable dielectric materials exhibiting low loss characteristics in the GHz frequencies are essential in the development of low power devices for microwave applications. We have applied a combinatorial synthetic methodology employing multiple atomic evaporative sources to produce compositional gradient thin film (Ba,Sr)(Ti,Mn)O3 perovskites. High throughput screening chips of both capacitive and waveguide structures are used to measure the compositional dependence of the dielectric properties of the fully characterised thin film materials. The co-planar waveguides are shown to allow measurements at frequencies exceeding 10 GHz. Using this methodology, we haveidentified (Ba,Sr)(Ti,Mn)O3 compositions which exhibit good tunability with low losses at microwave frequencies: for a single device with a 10 V DC bias one can achieve a 12 phase shift with excellent transmission characteristics, and an insertion loss of ~3.2 dB We show that small changes in composition can result in a significant change in dielectric characteristics and device performance, and that the experimental protocol developed provides a powerful methodology for the development of materials and microwave devices.

We report the properties of a series of electrodeposited Ge-Sb-Te alloys with various compositions. It is shown that the Sb/Ge ratio can be varied in a controlled way by changing the electrodeposition potential. This method opens up the prospect of depositing Ge-Sb-Te super-lattice structures by electrodeposition. Material and electrical characteristics of various compositions have been investigated in detail, showing up to three orders of magnitude resistance ratio between the amorphous and crystalline states and endurance up to 1000 cycles.