Sathish Chander Dhanabalan

Photonics and optoelectronics of two-dimensional materials beyond graphene

Apart from conventional materials, the study of two-dimensional (2D) materials has emerged as a significant field of study for a variety of applications. Graphene-like 2D materials are important elements of potential optoelectronics applications due to their exceptional electronic and optical properties. The processing of these materials towards the realization of devices has been one of the main motivations for the recent development of photonics and optoelectronics. The recent progress in photonic devices based on graphene-like 2D materials, especially topological insulators (TIs) and transition metal dichalcogenides (TMDs) with the methodology level discussions from the viewpoint of state-of-the-art designs in device geometry and materials are detailed in this review. We have started the article with an overview of the electronic properties and continued by highlighting their linear and nonlinear optical properties. The production of TIs and TMDs by different methods is detailed. The following main applications focused towards device fabrication are elaborated: (1) photodetectors, (2) photovoltaic devices, (3) light-emitting devices, (4) flexible devices and (5) laser applications. The possibility of employing these 2D materials in different fields is also suggested based on their properties in the prospective part. This review will not only greatly complement the detailed knowledge of the device physics of these materials, but also provide contemporary perception for the researchers who wish to consider these materials for various applications by following the path of graphene.

Emerging Trends in Phosphorene Fabrication towards Next Generation Devices

The challenge of science and technology is to design and make materials that will dominate the future of our society. In this context, black phosphorus has emerged as a new, intriguing two‐dimensional (2D) material, together with its monolayer, which is referred to as phosphorene. The exploration of this new 2D material demands various fabrication methods to achieve potential applications— this demand motivated this review. This article is aimed at supplementing the concrete understanding of existing phosphorene fabrication techniques, which forms the foundation for a variety of applications. Here, the major issue of the degradation encountered in realizing devices based on few‐layered black phosphorus and phosphorene is reviewed. The prospects of phosphorene in future research are also described by discussing its significance and explaining ways to advance state‐of‐art of phosphorene‐based devices. In addition, a detailed presentation on the demand for future studies to promote well‐systemized fabrication methods towards large‐area, high‐yield and perfectly protected phosphorene for the development of reliable devices in optoelectronic applications and other areas is offered.

Carbon-doped SiO x nanowires with a large yield of white emission

The growth of SiOx nanowires (NWs) with intense white emission is reported. Due to carbon monoxide gas being used as a dopant precursor, carbon-doped under-stoichiometric silicon dioxide NWs are obtained. The doping of the NWs is studied by means of x-ray photoelectron spectroscopy, which allows to assess the presence of carbon atoms in the silicon oxide amorphous structure. The light emission properties are studied by means of cathodoluminescence spectroscopy, which shows three main emission bands set at 2.7 eV (blue), 2.3 eV (green) and 1.9 eV (red), resulting in the white emission.

Black Phosphorus Quantum Dots as an Efficient Saturable Absorber for Bound Soliton Operation in an Erbium Doped Fiber Laser

We have investigated the nonlinear and ultrafast photonics of chemically processed black phosphorus quantum dots (BPQDs) synthesized by the solvothermal treatment approach, with an average lateral size of about 2.48 ± 0.4 nm. BPQDs exhibit optical saturable absorption measured by the balanced twin-detector measurement system at the telecommunication band and have been demonstrated for the generation of passively mode-locking operation in an erbium-doped fiber laser. Either two-pulse or three-pulse bound state of soliton pulse has been obtained, making the best use of the BPQDs-based saturable absorber. Our work suggests that BPQDs might be developed as an efficient optical saturable absorber for ultrafast photonics applications.

SiC Nanostructures Toward Biomedical Applications and Its Future Challenges

ABSTRACT The present work reviews current research activities for possible applications of silicon carbide (SiC) nanostructures. The main attention is devoted to emerging biomedical applications which can bring a boon for a healthy society. Highlights toward the widespread of SiC nanostructures in new fields of applications are reviewed and explained. This article surveys some of the recent work using SiC nanostructures in biomedical field, sensing, and energy harvesting including a review on nanostructure biocompatibility research to date. The review article begins with an overview of the state of art of silicon carbide along with their behavior, properties, and applications of SiC in bulk, thin films, and nanoscale forms, respectively. The multidisciplinary applications of SiC nanostructures are also highlighted. Different applications elaborated are as follows: (1) biomedical/nanomedical applications, (2) nanoelectronics, (3) sensing applications, (4) energy harvesting, and (5) other emerging areas. The possibility for employing SiC nanostructures to be accomplished in upgrading the existing devices is suggested based on their properties. This article is concluded with some challenges for future applications.

Effects of Growth Parameters on SiC/SiO2 Core/Shell Nanowires Radial Structures

Cubic silicon carbide - silicon dioxide core-shell nanowires have been synthesized in a thermal CVD system from carbon monoxide on silicon substrate. Using a non-ionic surfactant during the coating process of the substrate by the catalyst, the uniformity of the catalytic layer was improved, resulting in a more uniform nanowires growth. It is demonstrated that the core diameter is strongly correlated with the precursor concentration.

SiC NWs Grown on Silicon Substrate Using Fe as Catalyst

We report on the synthesis of SiC nanowires (NWs) using iron as catalyst. The NWs were grown on silicon substrate by vapour-liquid-solid (VLS) mechanism with propane and silane as precursors, both 3% diluted in hydrogen, and hydrogen as carrier gas. The growth temperature was 1250°C, to reach the eutectic values of the Si-Fe alloy and to permit the VLS mechanism. The as-grown SiC nanowires were characterized by scanning and transmission electron microscopy. The nanowires are from 30 to 100 nm in diameter and several μm in length, with <111> growth direction.

Fluorination‐Enhanced Ambient Stability and Electronic Tolerance of Black Phosphorus Quantum Dots

Abstract The environmental instability and uneliminable electronic trap states in black phosphorus quantum dots (BPQDs) limit the optoelectronics and related applications of BPQDs. Here, fluorinated BPQDs (F‐BPQDs) are successfully synthesized by using a facile electrochemical exfoliation and synchronous fluorination method. The F‐BPQDs exhibit robust ambient stability and limited fluorination capability, showing a nonstoichiometric fluorination degree (D F) maximum of ≈0.68. Density functional theory calculations confirm that due to the edge etching effect of fluorine adatoms, the simulated F‐BPQDs become structurally unstable when D F surpasses the limit. Furthermore, the trap states of BPQDs can be effectively eliminated via fluorination to obtain a coordination number of 3 or 5 for fluorinated and unfluorinated phosphorus atoms. The results reveal that the air‐stable F‐BPQDs exhibit fluorine defect‐enhanced electronic tolerance, which is crucial for nanophotonics and nanoelectronics applications.

Cubic Silicon Carbide Nanowires

Nowadays semiconductor nanowires (NWs) represent not only a field of great interest for the study of nanoscale new phenomena, but the technology has become increasingly mature insomuch as they are expected to give a fundamental contribution to electronic devices. Silicon carbide nanowires (SiC-NWs) embody a unique confluence of the well-known SiC chemical and mechanical peculiar properties with the size-dependent characteristics of quasi-one-dimensional structures. However, the synthesis of SiC nanostructures with tailored structure and their use in functional devices is still a challenge. In this chapter firstly a brief review on recent progress and the growth techniques used in literature to obtain SiC nanowires are introduced, then a survey of the growth mechanism of nanowires from vapour phase is presented. Some methods used to deposit catalysts for the growth are reviewed and the so called “dewetting” mechanism is analysed and studied with selected examples after a brief treatise of the thermodynamic of the phenomenon. The procedures for the synthesis of pure cubic silicon carbide nanowires by vapour phase epitaxy and core-shell SiC/SiO2 nanowires by chemical vapour deposition are presented and the morphology and structure are investigated by means of electronic microscopy. Finally, for core-shell nanowires, X-ray photoelectron spectroscopy is presented as a powerful technique to analyse the chemical and electronic state of the core and cathodoluminescence measurements show the influence of the shell on the optical emission of the SiC core embedded in the wires.