Two-dimensional crystals have emerged as a class of materials that may impact future electronic technologies. Experimentally identifying and characterizing new functional two-dimensional materials is challenging, but also potentially rewarding. Here, we fabricate field-effect transistors based on few-layer black phosphorus crystals with thickness down to a few nanometres. Reliable transistor performance is achieved at room temperature in samples thinner than 7.5 nm, with drain current modulation on the order of 10(5) and well-developed current saturation in the I-V characteristics. The charge-carrier mobility is found to be thickness-dependent, with the highest values up to ∼ 1,000 cm(2) V(-1) s(-1) obtained for a thickness of ∼ 10 nm. Our results demonstrate the potential of black phosphorus thin crystals as a new two-dimensional material for applications in nanoelectronic devices.

http://absimage.aps.org/image/MAR14/MWS_MAR14-2013-005031.pdf

Black Phosphorus Field-effect Transistors

Polarization-sensitive photodetectors are highly desirable for high-performance optical signal capture and stray light shielding in order to enhance the capability for detection and identification of targets in dark, haze, and other complex environments. Usually, filters and polarizers are utilized for conventional devices to achieve polarization-sensitive detection. Herein, to simplify the optical system, a two-dimensional self-powered polarization-sensitive photodetector is fabricated based on a stacked GeSe/MoS2 van der Waals (vdW) heterojunction which facilitates efficient separation and transportation of the photogenerated carriers because of type-II band alignment. Accordingly, a high-performance self-powered photodetector is achieved with merits of a very large on-off ratio photocurrent at zero bias of currently 104 and a high responsivity (Rλ) of 105 mA/W with an external quantum efficiency of 24.2%. Furthermore, a broad spectral photoresponse is extended from 380 to 1064 nm owing to the high absorption coefficient in a wide spectral region. One of the key benefits from these highly anisotropic orthorhombic structures of layered GeSe is self-powered polarization-sensitive detection with a peak/valley ratio of up to 2.95. This is realized irradiating with a 532 nm wavelength laser with which a maximum photoresponsivity of up to 590 mA/W is reached when the input polarization is parallel to the armchair direction. This work provides a facile route to fabricate self-powered polarization-sensitive photodetectors from GeSe/MoS2 vdW heterojunctions for integrated optoelectronic devices.

Polarization-Sensitive Self-Powered Type-II GeSe/MoS2 Van der Waals Heterojunction Photodetector

In the post-Moore era, 2D materials with rich physical properties have attracted widespread attention from the scientific and industrial communities. Among 2D materials, the 2D homojunctions are of great promise in designing novel electronic and optoelectronic devices due to their unique geometries and properties such as homogeneous components, perfect lattice matching, and efficient charge transfer at the interface. In this article, a pioneering review focusing on the structural design and device application of 2D homojunctions such as p-n homojunctions, heterophase homojunctions, and layer-engineered homojunctions is provided. The preparation strategies to construct 2D homojunctions including vapor-phase deposition, lithium intercalation, laser irradiation, chemical doping, electrostatic doping, and photodoping are summarized in detail. Specifically, a careful review on the applications of the 2D homojunctions in electronics (e.g., field-effect transistors, rectifiers, and inverters) and optoelectronics (e.g., light-emitting diodes, photovoltaics, and photodetectors) is provided. Eventually, the current challenges and future perspectives are commented for promoting the rapid development of 2D homojunctions.

2D Homojunctions for Electronics and Optoelectronics.

van der Waals (vdW) vertical p-n junctions based on two-dimensional (2D) materials have shown great potential in flexible, self-driven, high-efficiency electronic and optoelectronic applications. However, due to the complex nucleation dynamics, the controllable synthesis of vertical heterostructures remains a daunting challenge. Here, we report the controlled growth of vertical GaSe/MoS2 p-n heterojunctions via a liquid gallium (Ga)-assisted chemical vapor deposition method. The growth mechanism can be interpreted by theoretical calculations based on the Burton-Cabrera-Frank theory. By analyzing the diffusion barriers and the Ehrlich-Schwoebel barriers of adatoms, we found that the growth modes between vertical and lateral can be precisely switched by means of adjusting the amount of Ga. Based on the achieved high-quality vertical GaSe/MoS2 p-n heterojunctions, photosensing devices are further designed and systematically investigated. Upon light illumination, prominent photovoltaic effects with large open-circuit voltage (0.61 V) and broadband detection capability from 375 to 633 nm are observed, which can further be employed for self-powered photodetection with high responsivity (900 mA/W) and fast response speed (5 ms). The developed liquid-metal-assisted strategy provides an effective method for controllable synthesis of vdW heterostructures and will give impetus to their applications in high-performance optoelectronic device.

Liquid-Metal-Assisted Growth of Vertical GaSe/MoS 2 p-n Heterojunctions for Sensitive Self-Driven Photodetectors.

Reconfigurable logic-in-memory architectures based on a two-dimensional van der Waals heterostructure device

Construction of atomically thin p-n junctions helps to build highly compact electronic and photonic devices for on-chip optoelectronic applications. In this work, lateral nonvolatile MoTe2 p-n diodes are constructed on the basis of the MoTe2/h-BN/graphene semifloating gate field-effect transistor (SFG-FET) configuration. The achieved diodes exhibit excellent rectifying behaviors (rectification ratio up to 8 × 103) and typical photovoltaic properties (with power conversion efficiency of 0.5%). Through manipulating the polarity of the stored charges in the semifloating gate, such rectifying behaviors and photovoltaic properties can be erased, resulting in a high conduction state ( n + -n junction). Such erasable and programmable behaviors further enable us to develop logic optoelectronic devices, realizing the switching of the device between different power conversion states and functional AND and OR optical logic gates. We believe that the achieved MoTe2-based SFG-FET devices with interesting logic optoelectronic functions will enrich the modern photoelectrical interconnected circuits.

Nonvolatile MoTe 2 p-n Diodes for Optoelectronic Logics.

Two-dimensional (2D) heterostructures have been widely studied in recent years and are envisioned to play a key role in future integrated electronics and optoelectronics. The thus-involved van der Waals integration technique provides a feasible way to integrate different 2D materials even with diverse crystal structures into heterostructures, providing a promising platform to explore new artificial materials with new properties. Here, for the first time, we have successfully realized the combination of orthogonal selenide (SnSe) with hexagonal MoS2 into p–n heterojunctions though a two-step chemical vapor deposition method. High resolution transmission electron microscopy characterization shows that multilayer SnSe nanosheet is vertically stacked on MoS2 nanosheet with high crystallinity. The precise spatial modulation of SnSe/MoS2 heterostructures is verified by Raman diagrams. At the same time, the electrical and optoelectronic properties are probed though designing SnSe/MoS2 p–n junction devices. Typical current rectification behaviors are obviously observed in dark condition. While under light illumination, obvious photovoltaic behavior is observed. Maximum short-circuit current (I sc) and photon-electron conversion efﬁciency (η) are measured to be 67 nA and 1.8%, respectively. The results also indicate that the heterostructure can be employed for reliable ultra-sensitive photodetection, where maximum photoresponsivity is measured to be 384 A W−1. The direct vapor growth of 2D p–n junctions with different lattice symmetries may expand the platform for the realization of new 2D electronic and optoelectronic devices.

https://iopscience.iop.org/article/10.1088/2399-1984/abd53a/pdf

Controlled growth of SnSe/MoS2 vertical p–n heterojunction for optoelectronic applications

The newly emerged two-dimensional (2D) semiconducting materials, owning to the atomic thick nature and excellent optical and electrical properties, are considered as potential candidates to solve the bottlenecks of traditional semiconductors. However, the realization of high performance 2D semiconductor-based field-effect transistors (FETs) has been a longstanding challenge in 2D electronics, which is mainly ascribing to the presence of significant Schottky barrier (SB) at metal-semiconductor interfaces. Here, an additional contact gate is induced in 2D ambipolar FET to realize near ideal reconfigurable FET (RFET) devices without restrictions of SB. Benefitting from the consistently high doping of contact region, the effective SB height can be maintained at ultra-small value during all operation conditions, resulting in the near ideal subthreshold swing (SS) values (132 mV/decade for MoTe2 RFET and 67 mV/decade for WSe2 RFET) and the relatively high mobility (28.6 cm2/(V s) for MoTe2 RFET and 89.8 cm2/(V s) for WSe2 RFET). Moreover, the flexible control on the doping polarity of contact region enables the remodeling and switching of the achieved unipolar FETs between p-type mode and n-type mode. Based on such reconfigurable behaviors, high gain complementary MoTe2 inverters are further realized. The findings in this work push forward the development of high-performance 2D semiconductor integrated devices and circuits.

Contact and injection engineering for low SS reconfigurable FETs and high gain complementary inverters

The realization of light-triggered devices where light is used as external stimulus to control the device performances is a long-standing goal in modern opto-electrical interconnection circuits. In this work, it reveals that light illumination can induce the formation of p-n junctions along two-dimensional conduction channels. The results indicate that the dominant charge carrier type and density in black phosphorus (BP) conduction channel can be effectively modulated by the underlying cadmium sulfide (CdS) photo-gate layer under light illumination. This enables flexible switching of the working state between BP resistor and BP p-n diode in the designed semi-photo-gate transistor (SPGT) devices when switching the light on and off (ultra-low threshold light power). Simultaneously, the achieved BP p-n junctions also exhibit ultra-high photoresponsivity and evident photovoltaic properties. That is to say, light can be employed as external stimulus to define the BP p-n junctions, and in turn the p-n junctions will further convert the light into electrical power, showing all-in-one opto-electrical interconnection properties. Moreover, the SPGT device architecture is also applicable for construction of other ambipolar semiconductor-based (WSe2- and MoTe2-based) p-n diodes. Such universal all-in-one light-triggered lateral homogeneous p-n junctions with ultra-low energy consumption should open a new pathway toward novel optoelectronic devices and deliver various new applications.

Light-triggered two-dimensional lateral homogeneous p-n diodes for opto-electrical interconnection circuits

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Xingwang Wang

Author Tools

Chat about Author

Papers

Nonvolatile MoTe 2 p-n Diodes for Optoelectronic Logics.

Controlled growth of SnSe/MoS2 vertical p–n heterojunction for optoelectronic applications

Contact and injection engineering for low SS reconfigurable FETs and high gain complementary inverters

Light-triggered two-dimensional lateral homogeneous p-n diodes for opto-electrical interconnection circuits