다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Few-layered MoS2 as Schottky metal–semiconductor–metal photodetectors (MSM PDs) for use in harsh environments makes its debut as two-dimensional (2D) optoelectronics with high broadband gain (up to 13.3), high detectivity (up to ∼1010 cm Hz1/2/W), fast photoresponse (rise time of ∼70 μs and fall time of ∼110 μs), and high thermal stability (at a working temperature of up to 200 °C). Ultrahigh responsivity (0.57 A/W) of few-layer MoS2 at 532 nm is due to the high optical absorption (∼10% despite being less than 2 nm in thickness) and a high photogain, which sets up a new record that was not achievable in 2D nanomaterials previously. This study opens avenues to develop 2D nanomaterial-based optoelectronics for harsh environments in imaging techniques and light-wave communications as well as in future memory storage and optoelectronic circuits.

https://nanoenergy.kaust.edu.sa/Documents/1312.pdf

Few-Layer MoS2 with High Broadband Photogain and Fast Optical Switching for Use in Harsh Environments

One-dimensional (1D) metal-oxide nanostructures are ideal systems for exploring a large number of novel phenomena at the nanoscale and investigating size and dimensionality dependence of nanostructure properties for potential applications The construction and integration of photodetectors or optical switches based on such nanostructures with tailored geometries have rapidly advanced in recent years Active 1D nanostructure photodetector elements can be configured either as resistors whose conductions are altered by a charge-transfer process or as field-effect transistors (FET) whose properties can be controlled by applying appropriate potentials onto the gates Functionalizing the structure surfaces offers another avenue for expanding the sensor capabilities This article provides a comprehensive review on the state-of-the-art research activities in the photodetector field It mainly focuses on the metal oxide 1D nanostructures such as ZnO, SnO(2), Cu(2)O, Ga(2)O(3), Fe(2)O(3), In(2)O(3), CdO, CeO(2), and their photoresponses The review begins with a survey of quasi 1D metal-oxide semiconductor nanostructures and the photodetector principle, then shows the recent progresses on several kinds of important metal-oxide nanostructures and their photoresponses and briefly presents some additional prospective metal-oxide 1D nanomaterials Finally, the review is concluded with some perspectives and outlook on the future developments in this area

A comprehensive review of one-dimensional metal-oxide nanostructure photodetectors

The technological evolution has been progressing for centuries and will possibly increase at a higher rate in the 21st century. Currently, in this age of nanotechnology, the discovery of more economical and sustainable novel materials has considerably increased. The abundance of two-dimensional (2D) materials has endowed them with a broad material platform in technical studies and in the expansion of nano- and atomic-level applications. The innovation of graphene has motivated considerable attention to the study of other novel 2D materials, known as modern day “alchemy”, by which scientists are trying to convert most possible periodic table elements into 2D material structures and forms. 2D material devices with high quality and good optical encoder performance have a multitude of industrial applications. However, their stability and large size restrict their applications, but these problems can be overcome by functionalization and substrate-based formation of 2D materials. Therefore, via this review, first, basic attributes of 2D materials are described, and the mechanisms to further enhance their properties are also summarized. Second, the applications of 2D materials are discussed, along with their advantages and disadvantages. Finally, some effective device-fabrication approaches, such as heterostructure approaches, are applied to further enhance the properties of 2D materials; their novel device applications and opportunities are also presented. This updated review may provide new avenues for 2D material synthesis and development of more efficient devices compared to conventional devices in different fields.

Recent developments in emerging two-dimensional materials and their applications

This article presents a comprehensive review of the current research addressing the surface effects on physical properties and potential applications of nanostructured ZnO. Studies illustrating the transport, photoluminescence (PL), and photoconductivity properties of ZnO with ultrahigh surface-to-volume (S/V) ratio are reviewed first. Secondly, we exam- ine recent studies of the applications of nanostructured ZnO employing the surface effect on gas/chemical sensing, relying on a change of conductivity via electron trapping and detrap- ping process at the surfaces of nanostructures. Finally, we comprehensively review the photo - voltaic (PV) application of ZnO nanostructures. The ultrahigh S/V ratios of nanostructured devices suggest that studies on the synthesis and PV properties of various nanostructured ZnO for dye-sensitized solar cells (DSSCs) offer great potential for high efficiency and low- cost solar cell solutions. After surveying the current literature on the surface effects on nano - structured ZnO, we conclude this review with personal perspectives on a few surface-related issues that remain to be addressed before nanostructured ZnO devices can reach their ulti- mate potential as a new class of industrial applications.

Surface effects on optical and electrical properties of ZnO nanostructures

Ever since two dimensional-transition (2D) metal dichalcogenides (TMDs) were discovered, their fascinating electronic properties have attracted a great deal of attention for harnessing them as critical components in novel electronic devices 2D-TMDs endowed with an atomically thin structure, dangling bond-free nature, electrostatic integrity, and tunable wide band gaps enable low power consumption, low leakage, ambipolar transport, high mobility, superconductivity, robustness against short channel effects and tunneling in highly scaled devices However, the progress of 2D-TMDs has been hampered by severe charge transport issues arising from undesired phenomena occurring at the surfaces and interfaces Therefore, this review provides three distinct engineering strategies embodied with distinct innovative approaches to optimize both carrier injection and transport First, contact engineering involves 2D-metal contacts and tunneling interlayers to overcome metal-induced interface states and the Fermi level pinning effect caused by low vacancy energy formation Second, dielectric engineering covers high-k dielectrics, ionic liquids or 2D-insulators to screen scattering centers caused by carrier traps, imperfections and rough substrates, to finely tune the Fermi level across the band gap, and to provide dangling bond-free media Third, material engineering focuses on charge transfer via substitutional, chemical and plasma doping to precisely modulate the carrier concentration and to passivate defects while preserving material integrity Finally, we provide an outlook of the conceptual and technical achievements in 2D-TMDs to give a prospective view of the future development of highly scaled nanoelectronic devices

/pdf/charge-carrier-injection-and-transport-engineering-in-two-3b0djcj2tc.pdf

Charge carrier injection and transport engineering in two-dimensional transition metal dichalcogenides

The interaction between chemisorbed oxygen adatoms (O2(ad)−) and oxygen vacancies associated with the formation/rupture of conductive filaments dominates the switching yield of ZnO, which is also confirmed by the fact that the reduction of SET/RESET voltage with the temperature. The pronounced surface effect-induced conductivity lowering due to O2(ad)− chemisorption leads to increased resistance of high resistance state (HRS). The current decay of the HRS with increased temperatures/times is owing to the severe O2(ad)− chemisorption as Joule heating is continuously applied. The statistical analysis for over 400 cells provides essential evidence for evaluating the surface effect on resistive switching.

Surface effect on resistive switching behaviors of ZnO

Organic semiconductors demonstrate several advantages over conventional inorganic materials for novel electronic and optoelectronic applications, including molecularly tunable properties, flexibility, low-cost, and facile device integration. However, before organic semiconductors can be used for the next-generation devices, such as ultrafast photodetectors (PDs), it is necessary to develop new materials that feature both high mobility and ambient stability. Toward this goal, a highly stable PD based on the organic single crystal [PtBr2 (5,5'-bis(CF3 CH2 OCH2 )-2,2'-bpy)] (or "Pt complex (1o)") is demonstrated as the active semiconductor channel-a material that features a lamellar molecular structure and high-quality, intraligand charge transfer. Benefitting from its unique crystal structure, the Pt-complex (1o) device exhibits a field-effect mobility of ≈0.45 cm2 V-1 s-1 without loss of significant performance under ambient conditions even after 40 days without encapsulation, as well as immersion in distilled water for a period of 24 h. Furthermore, the device features a maximum photoresponsivity of 1 × 103 A W-1 , a detectivity of 1.1 × 1012 cm Hz1/2 W-1 , and a record fast response/recovery time of 80/90 µs, which has never been previously achieved in other organic PDs. These findings strongly support and promote the use of the single-crystal Pt complex (1o) in next-generation organic optoelectronic devices.

/pdf/fast-response-highly-air-stable-and-water-resistant-organic-di668i82yv.pdf

Fast-Response, Highly Air-Stable, and Water-Resistant Organic Photodetectors Based on a Single-Crystal Pt Complex

We demonstrated a nanocontacting scheme using a focus ion beam (FIB) system without further heat treatment for ZnO nanowires. This scheme includes Ga ion surface modification and direct-write Pt deposition induced by Ga ion, leading to an Ohmic nanocontact with a specific contact resistance as low as 2.5 × 10−6 Ω cm2. Temperature-dependent measurements show that the transport of the FIB-Pt contact on the ZnO nanowire with local surface modification is governed by field emission tunneling. Taking advantage of area-selected and room-temperature processes, Ga ion surface modification and direct-write Pt deposition using a FIB system demonstrates a feasible Ohmic scheme.

Jr-Jian Ke

Papers

Surface effects on optical and electrical properties of ZnO nanostructures

Charge carrier injection and transport engineering in two-dimensional transition metal dichalcogenides

Surface effect on resistive switching behaviors of ZnO

Fast-Response, Highly Air-Stable, and Water-Resistant Organic Photodetectors Based on a Single-Crystal Pt Complex

Development of Ohmic nanocontacts via surface modification for nanowire-based electronic and optoelectronic devices: ZnO nanowires as an example