Recent Advances in Black‐Phosphorus‐Based Photonics and Optoelectronics Devices

Black phosphorus, which is a relatively rare allotrope of phosphorus, was first discovered by Bridgman in 1914. Since the advent of two-dimensional (2D) black phosphorus (which is known as phosphorene due to its resembling graphene sheets) in early 2014, research interest in the arena of black phosphorus was reignited in the scientific and technological communities. Henceforth, a myriad of research studies on this new member of the 2D world have been extensively emerged. Fascinatingly, 2D black phosphorus exhibits a distinctive wrinkled structure with the high hole mobility up to 1000 cm2 V−1 s−1, excellent mechanical properties, tunable band structures, anisotropic thermal, electrical and optical properties, thus leading to its marvelous prospects in device applications. This review firstly introduces the state-of-the-art development, structural properties and preparation routes of black phosphorus. In particular, anisotropy involved in mechanical properties, thermal conductivity, carrier transport as well as optical properties is comprehensively discussed. Apart from discussing the recent progress in black phosphorus which is applied to devices (i.e. field effect transistors and optoelectronic), the review also highlights the bottlenecks encountered by the society and finally casts an invigorating perspective and insightful outlook on the future direction of the next-generation 2D black phosphorus by harnessing its remarkable characteristics for energy production.

The rapid development of the semiconductor industry calls for the exploration of novel semiconductors to cater to modern technical and commercial needs. Recently, black phosphorus (BP) has emerged as a new class of 2D semiconducting material and has attracted intensive research attention. The high carrier mobility and tunable direct bandgap of BP deliver great promise in photonic and optoelectronic device applications. Furthermore, the unique intrinsic anisotropy arising from the puckered structure can be exploited in the design of new devices. This review briefly introduces the history of BP and puts emphasis on recent advances pertaining to its optical properties and applications in the photonic and optoelectronic fields. From the perspective of mass production and practical use of BP, some of the research challenges and opportunities are discussed.

This paper reviews the recent progress on electronic and optoelectronic devices based on 2D black phosphorus (BP). First, the crystal structure, band structure, and optical properties of BP, as well as some currently-known passivation methods used for making BP stable in ambient conditions are briefly summarized. Device architectures and operating principles of the state-of-the-art few-layer BP based electronic and optoelectronic devices will then be discussed in detail, with a focus on field-effect transistors, heterojunction diodes, and photodetectors. Next, solution-based exfoliation methods aimed for addressing the scalability challenge faced by BP are briefly discussed, followed by their potential applications in gas sensors and biomedicine. By reviewing recent process and discussing remaining challenges faced by BP, this paper aims to provide perspectives on opportunities and future research directions for utilizing BP and moving towards practical applications.

Novel atomic-scale graphene metamaterials with broadband electromagnetic wave absorption and ultra-high elastic modulus

The study of transport and diffusion dynamics of quasi-particles such as excitons, trions, and biexcitons in two-dimensional (2D) semiconductors has opened avenues for their application in high-speed excitonic and optoelectronic devices. However, long-range transport and fast diffusion of these quasi-particles have not been reported for 2D systems such as transition metal dichalcogenides (TMDCs). The reported diffusion coefficients from TMDCs are low, limiting their use in high-speed excitonic devices and other optoelectronic applications. Here, we report the highest exciton diffusion coefficient value in monolayer WS2 achieved via engineering the radiative lifetime and diffusion lengths using static back-gate voltage and substrate engineering. Electrostatic doping is observed to modulate the radiative lifetime and in turn the diffusion coefficient of excitons by ∼three times at room temperature. By combining electrostatic doping and substrate engineering, we push the diffusion coefficient to an extremely high value of 86.5 cm2/s, which has not been reported before in TMDCs and is even higher than the values in some 1D systems. At low temperatures, we further report the control of dynamic and spatial diffusion of excitons, trions, and biexcitons from WS2. The electrostatic control of dynamics and transport of these quasi-particles in monolayers establishes monolayer TMDCs as ideal candidates for high-speed excitonic circuits, optoelectronic, and photonic device applications.

Motivated by the successful synthesis of 2D C2F diamanes [Bakharev, P.V. et al., Nat. Nanotechnol. 15, 59–66 (2020)], we have systematically investigated the structural stability, in-plane mechanical, optoelectronic, photocatalytic, piezoelectric, and thermoelectric properties of non-Janus and Janus diamanes monolayers named as C2H, C2F, C2Cl, C4HF, C4HCl and C4FCl. The structural stability is confirmed by cohesive energy, phonon dispersion spectra, and mechanical properties. The electronic properties has been calculated by HSE06 functional and the band gap are found to be 3.85, 5.64, 2.32, 4.16, 0.73 and 1.91 eV for C2H, C2F, C2Cl, C4HF, C4HCl and C4FCl, respectively. The hydrogen-containing non-Janus and Janus diamanes monolayers have a higher negative Poisson's ratio (NPR) and therefore are good auxetic materials. From the Poisson's ratio and Young's modulus of each configuration of non-Janus and Janus diamanes monolayer, anisotropic behavior was displayed. From the optical properties calculations, the refractive index values are around 1.5, which means that it will be a transparent monolayered materials. Also, C2Cl, C4HCl and C4FCl monolayers displayed high absorption spectra with an order of 105 cm−1 in the visible region, which shows great applications in optoelectronic devices. Additionally, the valence and conduction band-edge positions of 2D Janus and non-Janus diamanes of C2H, C2F, and C2Cl and C4HF monolayers have to straddle the redox potentials of water. It means that the photogenerated electrons and holes are sufficient to drive the overall water splitting. Whereas non-Janus diamanes C4HCl, and C4FCl monolayers displayed only water oxidation. The investigated in-plane piezoelectric coefficient has larger in non-Janus diamanes C4HF, C4HCl, and C4FCl monolayers. Therefore, it is very useful in the field of piezoelectric applications. From the thermoelectric properties, the non-Janus and Janus diamanes monolayers have great thermoelectric efficiency and were found to be 10.52 and 10.63% for C2H and C2F, respectively. Our results demonstrate the new class of 2D carbon-based monolayers has good auxetic materials as well as a wide range of applications in optoelectronics, piezoelectric, and thermoelectric fields.

Gamma ray has sufficient energy to ionize and displace of atoms when interacts with optoelectronic and photonic devices that are placed at γ-radiation exposure environment, can be exposed to gamma radiation, resulting the alteration of the physical properties and hence the performances of devices. A comprehensive investigation of physical properties of the semiconductor materials under the influence of gamma radiation is essential for the effective design of devices for the application in the radiation exposure environment. In this article, a potential candidate for optoelectronic and photonic devices, orthorhombic MoO3 nanoparticles with average crystallite size of 135.31 nm successfully synthesized by hydrothermal method. Then, the properties of nanoparticles exposed to low (10 kGy) and high (120 kGy) absorbed dose of γ-rays from 60Co source were characterized by XRD, FESEM, FTIR and UV–Vis–NIR spectrophotometer and effects of absorbed doses was investigated for the first time. A significant change is observed in different physical properties of α-MoO3 nanoparticles after gamma exposure. The XRD patterns reveal the average crystallite size, intensity and the degree of crystallinity decrease for low dose (10 kGy) and increases for high dose (120 kGy). The calculated average crystallite size exposed to low and high doses are 127.79 nm and 136 nm, respectively. The lattice strain and dislocation density, however, shows the opposite trend of crystallite size with absorbed doses. This result is good evidence for the deterioration of crystallinity for low dose and improvement for high dose. The FESEM results reveal the significant effects of gamma doses on the micrographs of layered structure and on grain size. The optical studies disclose that band gap increases gradually from 2.78 to 2.90 eV, this behavior is associated with the reduction of electronic localized states. These results suggest that α-MoO3 nanoparticles could tolerate high doses of gamma radiation, making it a promising candidate for optoelectronic and photonic devices for γ-ray exposure environment applications.

Gallium oxide is an exceptional ultra-wide bandgap material. Its most stable phase, β-Ga2O3, has been extensively studied and recently attracted much attention for various applications in electronics and optoelectronics. Recent research interest has also arisen in the study of two-dimensional β-Ga2O3, which might promise superior electrical, optical, thermal, and mechanical properties due to quantum confinement, high surface to volume ratio, and ease of integration with other materials. This work reviews and discusses facile, versatile, and economic methods such as exfoliation, spray pyrolysis, and oxide printing to produce few-nanometer thin β-Ga2O3 films. Optical properties and applications in optoelectronic devices are particularly highlighted, along with possible directions for future research.

In contrast to multi‐element ferroelectrics with intricate atomic configurations, single‐element ferroelectrics are distinguished by their structural simplicity and low‐dimensional nature. In addition, they have been experimentally verified to display robust ferroelectricity at room temperature. These materials are regarded as promising candidates for next‐generation flexible optoelectronic devices because of their high electrical conductivity and inherent compatibility with integrated circuits, this review systematically elucidates the underlying mechanisms governing the emergence of ferroelectricity in single‐element systems and comprehensively surveys the state‐of‐the‐art fabrication techniques. The fundamental physical properties of several prominent single‐element ferroelectrics including tellurium (Te), bismuth (Bi), and black phosphorus (BP) are discussed, highlighting their applications in memristors and optoelectronic devices. Finally, the current research challenges are addressed and future trends in material development, fabrication techniques, and potential applications are presented. The objective of this review is to provide a comprehensive understanding of single‐element ferroelectrics, offering valuable insights into their potential for broader applications. image

Strained layer quantum-well heterostructure semiconductor lasers and other optoelectronic devices are having an impact on nearly all applications of optoelectronics and especially fiber optic telecommunications. In this special issue on strained-layer optoelectronic materials and devices, the most recent advances in this fast-moving area of research are represented by 11 invited papers and 18 contributed papers. The research reported here covers an impressive range from detailed calculations and experimental data on the valence band structure and optical gain of strained layer heterostructures to the laser operating characteristics of devices made from these structures.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

DFT+U study of TlXBr3 (X = Sn, Ge) perovskites as next-generation materials for optoelectronics applications

p-type conductivity and the modulation of bandgap of ZnO are crucial aspects for realization of optoelectronic devices’ applications. The Li and Li-Cu could be suitable doping agents for achieving the p-type conductivity and the modulation of bandgap of ZnO. To this point of view, the Zn[Formula: see text]Li[Formula: see text]O (x = 0 to 40 at.%) and Zn[Formula: see text]Li[Formula: see text]Cu[Formula: see text]O (fixed, x = 5 at.%, and y = 0.0 to 10 at.%) thin films were prepared on the microscopic glass substrates at a temperature of 350[Formula: see text]C using cost effective chemical spray pyrolysis (CSP) technique. Field emission scanning electron microscope images show the coexistence of interconnected fibrous and flat grains on the films surface. The grain size changes as function of Li- and Li-Cu concentrations, and at a higher doping granular grains are observed. The successful incorporation of Li and Cu-Li into ZnO crystal is confirmed by X-ray photoelectron spectroscopy (XPS) measurements. The X-ray diffraction (XRD) patterns exhibit hexagonal polycrystalline structure of doped ZnO. However, the crystallinity is deteriorated at higher Li- and Li-Cu doping concentrations. The optical bandgap study exhibits direct transition type and it is red shifted from 3.21 to 2.61 eV and 2.84 to 3.56 eV for Li and Li-Cu doping in ZnO thin films, respectively. The optical conductivity enhances as a result of Li- and Li-Cu doping in ZnO. Therefore, Li- and Li-Cu can effectively be doped to tune bandgap and enhance optical properties of ZnO for electronic and optoelectronic device applications.

Owning to their superior electronic and optical properties, silicon nanomembranes (NMs) have attracted considerable attention to be exploited as fundamental building blocks for the applications in electronics, photonics, and optoelectronics. Nevertheless, small photon traveling distance in such ultra‐thin silicon (UT‐Si) nanomembranes with nanoscale thicknesses (50 nm) induces low total light absorption, which is crucial for optoelectronic applications. Here, a convenient and controllable strategy, involving self‐assembly of dielectric polystyrene (PS) microsphere array on UT‐Si, was proposed to enhance optoelectronic responses of UT‐Si‐based photodetectors in broadband. Scattering effect of PS microspheres facilitates to couple incident light into UT‐Si layer, thus enhancing the light absorption. UT‐Si‐based metal‐semiconductor‐metal (MSM) photodetectors with a PS microspehere array demonstrate significant enhancement in optoelectronic response compared with the photodetector without PS microspeheres. Furthermore, the response spectrum can be controllably tuned by adjusting the size of paved microspeheres. This research may provide a practical and cost‐efficient approach for enhancing the optoelectronic responses of nanomaterials with nanoscale thicknesses, thus expediting their potential applications in optoelectronic devices.

As the demand for data-driven technologies such as cloud computing, artificial intelligence, and the Internet of Things increases, the value of data centers rises. However, the cost of optical interconnects that convert optical signals to electrical signals and vice versa limits the bandwidth in these data centers. Historically the optoelectronic materials of group III–V semiconductor materials are grown using epitaxy and transferred to silicon microelectronics using robotic pick-and-place technology. This costly method restricts the large-scale production of on-chip optoelectronic components such as diodes, photodetectors, and lasers. In this dissertation, we investigated the potential of black phosphorus (BP) as a material for optoelectronic devices and aerosol jet printing (AJP) as a viable deposition method. AJP-compatible inks were synthesized by mixing liquid-phase exfoliated HEBM BP flakes with isopropanol and 2-butanol solvents. The resulting printed thin films of HEBM BP exhibited photoluminescence emission suitable for optically pumped devices. Similarly, exfoliated single-crystal BP flakes were mixed with isopropanol, water, and 2-butanol to produce an AJP-compatible ink. Thin films printed on SiO2 with chemical vapor transport grown BP (CVT-BP) inks exhibited photoluminescence emission and electrical properties suitable for optically and electrically pumped optoelectronic devices. We demonstrate that these inks can be printed on various surfaces, such as flexible polyimide, glass, conformal quartz tubes, pre-deposited graphene, and WS2. We examined the relationship between BP's microstructure and its electrical and optical properties using high-resolution transmission electron microscopy. Using a previously established analytical density gradient ultracentrifugation (DGU) model, we purified polydisperse converted-BP dispersions into monolayer dispersions to exploit the layer-dependent bandgap of BP. In addition, we demonstrated that cascade centrifugation and tangential flow filtration (TFF) could be used to generate larger quantities of purified samples. We show that combining cascade centrifugation and TFF BP is an effective solution processing method for BP inks by enabling purification, surfactant removal, solvent exchange, and dispersion concentration. Our results indicate that AJP-printed BP has the potential to function as an active material in optoelectronic devices.

Unlike periodic and random structures, many aperiodic structures exhibit unique hierarchical natures. Aperiodic photonic micro/nanostructures usually support optical multimodes due to either the rich variety of unit cells or their hierarchical structure. Mainly based on our recent studies on this topic, here we review some developments of aperiodic-order-induced multimode effects and their applications in optoelectronic devices. It is shown that self-similarity or mirror symmetry in aperiodic micro/nanostructures can lead to optical or plasmonic multimodes in a series of one-dimensional/two-dimensional (1D/2D) photonic or plasmonic systems. These multimode effects have been employed to achieve optical filters for the wavelength division multiplex, open cavities for light–matter strong coupling, multiband waveguides for trapping “rainbow”, high-efficiency plasmonic solar cells, and transmission-enhanced plasmonic arrays, etc. We expect that these investigations will be beneficial to the development of integrated photonic and plasmonic devices for optical communication, energy harvesting, nanoantennas, and photonic chips.