The development of silicon semiconductor technology has produced breakthroughs in electronics—from the microprocessor in the late 1960s to early 1970s, to automation, computers and smartphones—by downscaling the physical size of devices and wires to the nanometre regime. Now, graphene and related two-dimensional (2D) materials offer prospects of unprecedented advances in device performance at the atomic limit, and a synergistic combination of 2D materials with silicon chips promises a heterogeneous platform to deliver massively enhanced potential based on silicon technology. Integration is achieved via three-dimensional monolithic construction of multifunctional high-rise 2D silicon chips, enabling enhanced performance by exploiting the vertical direction and the functional diversification of the silicon platform for applications in opto-electronics and sensing. Here we review the opportunities, progress and challenges of integrating atomically thin materials with silicon-based nanosystems, and also consider the prospects for computational and non-computational applications. Progress in integrating atomically thin two-dimensional materials with silicon-based technology is reviewed, together with the associated opportunities and challenges, and a roadmap for future applications is presented.

Graphene and two-dimensional materials for silicon technology.

Phosphorene, an emerging two-dimensional material, has received considerable attention due to its layer-controlled direct bandgap, high carrier mobility, negative Poisson's ratio and unique in-plane anisotropy. As cousins of phosphorene, 2D group-VA arsenene, antimonene and bismuthene have also garnered tremendous interest due to their intriguing structures and fascinating electronic properties. 2D group-VA family members are opening up brand-new opportunities for their multifunctional applications encompassing electronics, optoelectronics, topological spintronics, thermoelectrics, sensors, Li- or Na-batteries. In this review, we extensively explore the latest theoretical and experimental progress made in the fundamental properties, fabrications and applications of 2D group-VA materials, and offer perspectives and challenges for the future of this emerging field.

/pdf/recent-progress-in-2d-group-va-semiconductors-from-theory-to-340ay01tfh.pdf

Recent progress in 2D group-VA semiconductors: from theory to experiment

This Review covers recent progress and current challenges in the synthesis and stabilization of elemental 2D materials — topical species with peculiar properties. The further development of preparative methodologies will help to expand the 2D materials library well beyond naturally occurring layered materials, and afford products with unique structures and functions.

Synthesis and chemistry of elemental 2D materials

2D phosphorene, arsenene, antimonene, and bismuthene, as a fast-growing family of 2D monoelemental materials, have attracted enormous interest in the scientific community owing to their intriguing structures and extraordinary electronic properties. Tuning the monoelemental crystals into bielemental ones between group-VA elements is able to preserve their advantages of unique structures, modulate their properties, and further expand their multifunctional applications. Herein, a review of the historical work is provided for both theoretical predictions and experimental advances of 2D V-V binary materials. Their various intriguing electronic properties are discussed, including band structure, carrier mobility, Rashba effect, and topological state. An emphasis is also given to their progress in fabricated approaches and potential applications. Finally, a detailed presentation on the opportunities and challenges in the future development of 2D V-V binary materials is given.

2D V-V Binary Materials: Status and Challenges.

Axions are weakly interacting particles of low mass, and were postulated more than 30 years ago in the framework of the Standard Model of particle physics. Their existence could explain the missing dark matter of the Universe. However, despite intensive searches, axions have yet to be observed. Here we show that magnetic fluctuations of topological insulators couple to the electromagnetic fields exactly like the axions, and propose several experiments to detect this dynamical axion field. In particular, we show that the axion coupling enables a nonlinear modulation of the electromagnetic field, leading to attenuated total reflection. We propose a new optical-modulator device based on this principle. Axions are hypothetical particles that might play an important part in particle physics, astrophysics and cosmology. So far they have eluded observation, but theoretical work now predicts that axion physics might be explored in condensed-matter systems known as topological insulators.

http://absimage.aps.org/image/MAR10/MWS_MAR10-2009-001051.pdf

Dynamical Axion Field in Topological Magnetic Insulators

van der Waals epitaxy and electronic transport in topological insulators

We present a miniature passive wireless resonant sensor and its use in a novel platform for chemical-memory-based threshold sensing. The sensors are microfabricated with polyimide passivation and utilize various customizable polymer sensor layers allowing for capacitive transduction. Sensors of $\approx 2$ -mm3 active volume and 8-mm working distance are demonstrated, with experimental data for sensing using multiple polymers in multiple solvents. The novel design with configurable sensor layers enables a versatile platform for chemical and environmental monitoring applications.

Miniature Passive Wireless Resonant Platform for Chemical Memory-Based Threshold Sensing

We report on time–frequency analysis (TFA) of dispersion in a 1-D magneto-inductive waveguide (MIW). The short-time Fourier transform (STFT) and Wigner–Ville distribution (WVD) are used to localize the frequency content of the dispersed wave as a function of time and to estimate the group velocity in experiments using a 1-D MIW constructed with planar resonators. Time-domain reflectometry (TDR) measurements are performed after deliberately introducing defects along the waveguide; and the results are analyzed with TFA, demonstrating the potential for using such MIW-TDR configurations as sensors. The WVD-TFA is shown to provide precise time–frequency information, accurate defect localization, and group velocity estimation, confirming the slow wave long-range nature of dispersive MIWs. The adaptability of the MIW-TDR setup and the accuracy of the WVD for localization make the technique a suitable candidate for sensing applications using engineered dispersive media.

Group Velocity Estimation and Defect Localization in Magneto-Inductive Waveguides

This paper summarizes ongoing work on applying passive magneto-inductive (MI) waveguides as wireless sensor arrays
to monitor corrosion in infrastructure systems. The passive uniformly-spaced sensor array provides a low-cost and quick
method to detect the onset of corrosion in concrete structures using a noninvasive approach. The embedded sensors
communicate with neighboring sensors through inductive coupling. The corrosion information is interpreted based on
both frequency and time domain characteristics. Bandpass characteristics in the frequency domain and received reflected
time domain waves are investigated to locate the defects along the wireless sensor array. Using the relationship between
the relative positions of defects and MI waveguide performances, a new combined technique to determine location of
defects has been developed and proven to provide both improved sensitivity and defect location capability.

Improved magneto-inductive waveguide as wireless sensor net for structural health monitoring

We develop a model to quantify the signal strength in passive inductively coupled resonant sensor (PICRS) systems. We also explore the relationship between detectability and signal strength, which is critical for signal strength-sensitive applications. Either the phase or magnitude of the input impedance of a coupled reader can be used as a measurand; here, we focus on phase, but the model can be easily adapted to other measurands. The model employs dimensionless parameters, i.e., the quality factor ( $Q$ ) of the PICRS and coupling factor ( $k$ ) between the reader and PICRS. We experimentally verify the model using readers and sensors of different $Q$ and $k$ factors. The model incorporates the effect of the reader coil, which is essential for co-selection of readers and sensors. This model can find broader application as a tool for the design and detection of nonisochronous weakly coupled resonant sensors.

http://ieeexplore.ieee.org/ielam/7782634/8239616/8239637-aam.pdf

Tanuj Trivedi

Papers

van der Waals epitaxy and electronic transport in topological insulators

Miniature Passive Wireless Resonant Platform for Chemical Memory-Based Threshold Sensing

Group Velocity Estimation and Defect Localization in Magneto-Inductive Waveguides

Improved magneto-inductive waveguide as wireless sensor net for structural health monitoring

Quantitative Modeling of Phase Detection in Passive Inductively Coupled Resonant Sensors