2D MoS2 Encapsulated Silicon Nanopillar Array with High-Performance Light Trapping Obtained by Direct CVD Process

Weak absorption remains a vital factor that limits the application of two-dimensional (2D) materials due to the atomic thickness of those materials. In this work, a direct chemical vapor deposition (CVD) process was applied to achieve 2D MoS2 encapsulation onto the silicon nanopillar array substrate (NPAS). Single-layer 2D MoS2 monocrystal sheets were obtained, and the percentage of the encapsulated surface of NPAS was up to 80%. The reflection and transmittance of incident light of our 2D MoS2-encapsulated silicon substrate within visible to shortwave infrared were significantly reduced compared with the counterpart planar silicon substrate, leading to effective light trapping in NPAS. The proposed method provides a method of conformal deposition upon NPAS that combines the advantages of both 2D MoS2 and its substrate. Furthermore, the method is feasible and low-cost, providing a promising process for high-performance optoelectronic device development.

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Bio-Separated and Gate-Free 2D MoS2 Biosensor Array for Ultrasensitive Detection of BRCA1

Nanomaterials ◽

10.3390/nano11020545 ◽

2021 ◽

Vol 11 (2) ◽

pp. 545

Author(s):

Yi Zhang ◽

Wei Jiang ◽

Dezhi Feng ◽

Chenguang Wang ◽

Yi Xu ◽

...

Keyword(s):

High Performance ◽

Low Cost ◽

Chemical Vapor ◽

Signal Interference ◽

Ultrasensitive Detection ◽

Chemical Vapor Deposition Growth ◽

Biosensor Array ◽

Growth Method ◽

Biological Modification ◽

Biological Solutions

2D molybdenum disulfide (MoS2)-based thin film transistors are widely used in biosensing, and many efforts have been made to improve the detection limit and linear range. However, in addition to the complexity of device technology and biological modification, the compatibility of the physical device with biological solutions and device reusability have rarely been considered. Herein, we designed and synthesized an array of MoS2 by employing a simple-patterned chemical vapor deposition growth method and meanwhile exploited a one-step biomodification in a sensing pad based on DNA tetrahedron probes to form a bio-separated sensing part. This solves the signal interference, solution erosion, and instability of semiconductor-based biosensors after contacting biological solutions, and also allows physical devices to be reused. Furthermore, the gate-free detection structure that we first proposed for DNA (BRCA1) detection demonstrates ultrasensitive detection over a broad range of 1 fM to 1 μM with a good linear response of R2 = 0.98. Our findings provide a practical solution for high-performance, low-cost, biocompatible, reusable, and bio-separated biosensor platforms.

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Synthesis of single-crystalline GeS nanoribbons for high sensitivity visible-light photodetectors

Journal of Materials Chemistry C ◽

10.1039/c5tc01435b ◽

2015 ◽

Vol 3 (31) ◽

pp. 8074-8079 ◽

Cited By ~ 66

Author(s):

Changyong Lan ◽

Chun Li ◽

Yi Yin ◽

Huayang Guo ◽

Shuai Wang

Keyword(s):

Visible Light ◽

Vapor Deposition ◽

High Performance ◽

Incident Light ◽

Chemical Vapor ◽

High Sensitivity ◽

Single Crystalline ◽

Promising Application ◽

Photo Detection ◽

First Time

Single-crystalline GeS nanoribbons were synthesized by chemical vapor deposition for the first time. The nanoribbon photodetectors respond to the entire visible incident light with a response edge at around 750 nm and a high responsivity, indicating their promising application for high performance broadband visible-light photo-detection.

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Silicon Substrate Treated with Diluted NaOH Aqueous for Si/PEDOT: PSS Heterojunction Solar Cell with Performance Enhancement

Energies ◽

10.3390/en13184659 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4659

Author(s):

Tao Chen ◽

Hao Guo ◽

Leiming Yu ◽

Tao Sun ◽

Yu Yang

Keyword(s):

Aqueous Solution ◽

Solar Cell ◽

Silicon Substrate ◽

High Performance ◽

Immersion Time ◽

Performance Enhancement ◽

Light Trapping ◽

Short Circuit ◽

Short Circuit Current ◽

Short Circuit Current Density

Si/PEDOT: PSS solar cell is an important alternative for photovoltaic device due to its anticipated high theoretical efficiency and simple manufacturing process. In this study, processing silicon substrate with diluted NaOH aqueous solution was found to be an effective method for improving device performance, one that notably improves junction quality and light trapping ability. When immersed in diluted NaOH aqueous solution, the junction quality was improved according to the enlarged fill factor, reduced series resistance, and enhanced minor carrier lifetime. The diluted NaOH aqueous solution immersion etched the silicon surface and helped with the enhancement of light trapping ability, further improving the short-circuit current density. Although diluted NaOH aqueous solution immersion for bare silicon could improve the performance of devices, proper immersion time was needed. The influence of immersion time on device performances was investigated. The photovoltaic conversion efficiency easily increased from 10.01% to 12.05% when silicon substrate was immersed in diluted NaOH aqueous for 15 min. This study contributes to providing efficient and convenient methods for preparing high performance Si/PEDOT: PSS solar cells.

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Low Cost Environmental Sensors Using Zinc Oxide Nanowires and Nanostructures

MRS Proceedings ◽

10.1557/opl.2012.1218 ◽

2012 ◽

Vol 1439 ◽

pp. 139-144 ◽

Cited By ~ 2

Author(s):

Nima Mohseni Kiasari ◽

Saeid Soltanian ◽

Bobak Gholamkhass ◽

Peyman Servati

Keyword(s):

Zinc Oxide ◽

Metal Oxide ◽

High Performance ◽

Low Cost ◽

Chemical Vapor ◽

Environmental Sensors ◽

X Ray Diffraction ◽

Zinc Oxide Nanowires ◽

Oxide Nanowires ◽

Current Voltage

ABSTRACTZinc oxide (ZnO) nanowires (NW) are grown on both silicon and sapphire substrates using conventional chemical vapor deposition (CVD) system. As-grown nanostructures are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) as well as energy dispersive spectroscopy (EDS) and the results confirm high-quality c-axis growth of single-crystalline zinc oxide nanowires. Nanowire are dispersed in solvent and then placed between micro-patterned gold electrodes fabricated on silicon wafers using low cost and scalable dielectrophoresis (DEP) process for fabrication of oxygen and humidity sensors. These sensors are characterized in a vacuum chamber connected to a semiconductor analyzer. Current-voltage characteristics of each device are systematically investigated under different hydrostatic pressure of various gaseous environments such as nitrogen, argon, dry and humid air. It is observed that the electrical conductivity of the nanowires is significantly dependent on the number of oxygen and water molecules adsorbed to the surface of the metal oxide nanowire. These results are critical for development of low cost metal oxide sensors for high performance ubiquitous environmental sensors of oxygen and humidity.

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III–V Nanowires: Synthesis, Property Manipulations, and Device Applications

Journal of Nanomaterials ◽

10.1155/2014/702859 ◽

2014 ◽

Vol 2014 ◽

pp. 1-14 ◽

Cited By ~ 22

Author(s):

Ming Fang ◽

Ning Han ◽

Fengyun Wang ◽

Zai-xing Yang ◽

SenPo Yip ◽

...

Keyword(s):

High Performance ◽

Low Cost ◽

Volume Ratio ◽

Chemical Vapor ◽

Cost Effective ◽

Research Field ◽

Synthesis Methods ◽

Comprehensive Overview ◽

Device Applications ◽

Property Control

III–V semiconductor nanowire (NW) materials possess a combination of fascinating properties, including their tunable direct bandgap, high carrier mobility, excellent mechanical flexibility, and extraordinarily large surface-to-volume ratio, making them superior candidates for next generation electronics, photonics, and sensors, even possibly on flexible substrates. Understanding the synthesis, property manipulation, and device integration of these III–V NW materials is therefore crucial for their practical implementations. In this review, we present a comprehensive overview of the recent development in III–V NWs with the focus on their cost-effective synthesis, corresponding property control, and the relevant low-operating-power device applications. We will first introduce the synthesis methods and growth mechanisms of III–V NWs, emphasizing the low-cost solid-source chemical vapor deposition (SSCVD) technique, and then discuss the physical properties of III–V NWs with special attention on their dependences on several typical factors including the choice of catalysts, NW diameters, surface roughness, and surface decorations. After that, we present several different examples in the area of high-performance photovoltaics and low-power electronic circuit prototypes to further demonstrate the potential applications of these NW materials. Towards the end, we also make some remarks on the progress made and challenges remaining in the III–V NW research field.

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High-Sensitivity Flexible Pressure Sensor-Based 3D CNTs Sponge for Human–Computer Interaction

Polymers ◽

10.3390/polym13203465 ◽

2021 ◽

Vol 13 (20) ◽

pp. 3465

Author(s):

Jianli Cui ◽

Xueli Nan ◽

Guirong Shao ◽

Huixia Sun

Keyword(s):

Pressure Sensor ◽

High Performance ◽

Large Scale ◽

Low Cost ◽

Pressure Sensors ◽

Chemical Vapor ◽

High Sensitivity ◽

Wearable Electronics ◽

Wide Range ◽

Flexible Pressure Sensors

Researchers are showing an increasing interest in high-performance flexible pressure sensors owing to their potential uses in wearable electronics, bionic skin, and human–machine interactions, etc. However, the vast majority of these flexible pressure sensors require extensive nano-architectural design, which both complicates their manufacturing and is time-consuming. Thus, a low-cost technology which can be applied on a large scale is highly desirable for the manufacture of flexible pressure-sensitive materials that have a high sensitivity over a wide range of pressures. This work is based on the use of a three-dimensional elastic porous carbon nanotubes (CNTs) sponge as the conductive layer to fabricate a novel flexible piezoresistive sensor. The synthesis of a CNTs sponge was achieved by chemical vapor deposition, the basic underlying principle governing the sensing behavior of the CNTs sponge-based pressure sensor and was illustrated by employing in situ scanning electron microscopy. The CNTs sponge-based sensor has a quick response time of ~105 ms, a high sensitivity extending across a broad pressure range (less than 10 kPa for 809 kPa−1) and possesses an outstanding permanence over 4,000 cycles. Furthermore, a 16-pixel wireless sensor system was designed and a series of applications have been demonstrated. Its potential applications in the visualizing pressure distribution and an example of human–machine communication were also demonstrated.

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Bottom-up synthesis of graphene films hosting atom-thick molecular-sieving apertures

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2022201118 ◽

2021 ◽

Vol 118 (37) ◽

pp. e2022201118 ◽

Cited By ~ 1

Author(s):

Luis Francisco Villalobos ◽

Cédric Van Goethem ◽

Kuang-Jung Hsu ◽

Shaoxian Li ◽

Mina Moradi ◽

...

Keyword(s):

High Performance ◽

State Of The Art ◽

Scale Up ◽

Single Layer ◽

Chemical Vapor ◽

Single Layer Graphene ◽

Bottom Up ◽

Vacancy Defects ◽

Graphene Lattice ◽

Molecular Sieving

Incorporation of a high density of molecular-sieving nanopores in the graphene lattice by the bottom-up synthesis is highly attractive for high-performance membranes. Herein, we achieve this by a controlled synthesis of nanocrystalline graphene where incomplete growth of a few nanometer-sized, misoriented grains generates molecular-sized pores in the lattice. The density of pores is comparable to that obtained by the state-of-the-art postsynthetic etching (1012 cm−2) and is up to two orders of magnitude higher than that of molecular-sieving intrinsic vacancy defects in single-layer graphene (SLG) prepared by chemical vapor deposition. The porous nanocrystalline graphene (PNG) films are synthesized by precipitation of C dissolved in the Ni matrix where the C concentration is regulated by controlled pyrolysis of precursors (polymers and/or sugar). The PNG film is made of few-layered graphene except near the grain edge where the grains taper down to a single layer and eventually terminate into vacancy defects at a node where three or more grains meet. This unique nanostructure is highly attractive for the membranes because the layered domains improve the mechanical robustness of the film while the atom-thick molecular-sized apertures allow the realization of large gas transport. The combination of gas permeance and gas pair selectivity is comparable to that from the nanoporous SLG membranes prepared by state-of-the-art postsynthetic lattice etching. Overall, the method reported here improves the scale-up potential of graphene membranes by cutting down the processing steps.

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Low-Temperature Growth of Epitaxial Semiconductor Nanostructures and Films

MRS Proceedings ◽

10.1557/opl.2011.630 ◽

2011 ◽

Vol 1308 ◽

Author(s):

Alp T. Findikoglu ◽

Daniel E. Perea ◽

S. T. Picraux

Keyword(s):

Low Temperatures ◽

High Performance ◽

Low Cost ◽

Ion Beam ◽

Chemical Vapor ◽

Catalyst Layer ◽

Semiconductor Nanostructures ◽

Device Fabrication ◽

Single Crystalline ◽

Glass Substrates

ABSTRACTThe growth of epitaxial semiconductor nanostructures and films at low temperatures is important for semiconductor technology because it allows the possibility of monolithically integrating different high-performance single-crystalline semiconductor structures directly onto low cost technologically important substrates. At sufficiently low temperatures this can enable, for example, Si or Ge device fabrication on flexible substrates such as plastics. We have studied the reduced-temperature liquid-mediated growth of Ge nanostructures and films on crystalline template layers on non-single-crystalline substrates in a low-pressure chemical vapor deposition (LPCVD) system. The heteroepitaxial process is implemented by the Au seeded vapor-liquidsolid (VLS) catalytic growth technique with germane below 400 ºC. Crystalline template layers were prepared with ion-beam-assisted-deposition (IBAD) texturing and electron-beam evaporation on glass substrates. A thin layer of e-beam evaporated Au forms the catalyst layer, upon which we grew Ge films at 386 ºC. Scanning electron microscopy and x-ray diffraction results indicated that both Ge islands and nanowires grew heteroepitaxially on the crystalline template layers on glass substrates with good alignment over large areas.

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Simulation Study on the Effect of Doping Concentrations on the Photodetection Properties of Mg2Si/Si Heterojunction Photodetector

Photonics ◽

10.3390/photonics8110509 ◽

2021 ◽

Vol 8 (11) ◽

pp. 509

Author(s):

Hong Yu ◽

Chenggui Gao ◽

Jiang Zou ◽

Wensheng Yang ◽

Quan Xie

Keyword(s):

Energy Band ◽

Dark Current ◽

High Performance ◽

Structural Model ◽

Low Cost ◽

Simulation And Optimization ◽

Photoelectric Properties ◽

Silvaco Atlas ◽

Shortwave Infrared ◽

Ratio Response

To develop and design an environmentally friendly, low-cost shortwave infrared (SWIR) photodetector (PD) material and extend the optical response cutoff wavelengths of existing silicon photodetectors beyond 1100 nm, high-performance silicon-compatible Mg2Si/Si PDs are required. First, the structural model of the Mg2Si/Si heterojunction was established using the Silvaco Atlas module. Second, the effects of the doping concentrations of Mg2Si and Si on the photoelectric properties of the Mg2Si/Si heterojunction PD, including the energy band, breakdown voltage, dark current, forward conduction voltage, external quantum efficiency (EQE), responsivity, noise equivalent power (NEP), detectivity, on/off ratio, response time, and recovery time, were simulated. At different doping concentrations, the heterojunction energy band shifted, and a peak barrier appeared at the conduction band of the Mg2Si/Si heterojunction interface. When the doping concentrations of Si and Mg2Si layer were 1017, and 1016 cm−3, respectively, the Mg2Si/Si heterojunction PD could obtain optimal photoelectric properties. Under these conditions, the maximum EQE was 70.68% at 800 nm, the maximum responsivity was 0.51 A/W at 1000 nm, the minimum NEP was 7.07 × 10−11 WHz–1/2 at 1000 nm, the maximum detectivity was 1.4 × 1010 Jones at 1000 nm, and the maximum on/off ratio was 141.45 at 1000 nm. The simulation and optimization result also showed that the Mg2Si/Si heterojunction PD could be used for visible and SWIR photodetection in the wavelength range from 400 to 1500 nm. The results also provide technical support for the future preparation of eco-friendly heterojunction photodetectors.

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Simple Self-Assembly Strategy of Nanospheres on 3D Substrate and Its Application for Enhanced Textured Silicon Solar Cell

Nanomaterials ◽

10.3390/nano11102581 ◽

2021 ◽

Vol 11 (10) ◽

pp. 2581

Author(s):

Dan Su ◽

Lei Lv ◽

Yi Yang ◽

Huan-Li Zhou ◽

Sami Iqbal ◽

...

Keyword(s):

Self Assembly ◽

High Performance ◽

Light Trapping ◽

Incident Light ◽

Three Dimensional ◽

Cost Effective ◽

Optical Measurements ◽

Sio2 Coating ◽

Assembly Strategy ◽

Cost Effective Approach

Nanomaterials and nanostructures provide new opportunities to achieve high-performance optical and optoelectronic devices. Three-dimensional (3D) surfaces commonly exist in those devices (such as light-trapping structures or intrinsic grains), and here, we propose requests for nanoscale control over nanostructures on 3D substrates. In this paper, a simple self-assembly strategy of nanospheres for 3D substrates is demonstrated, featuring controllable density (from sparse to close-packed) and controllable layer (from a monolayer to multi-layers). Taking the assembly of wavelength-scale SiO2 nanospheres as an example, it has been found that textured 3D substrate promotes close-packed SiO2 spheres compared to the planar substrate. Distribution density and layers of SiO2 coating can be well controlled by tuning the assembly time and repeating the assembly process. With such a versatile strategy, the enhancement effects of SiO2 coating on textured silicon solar cells were systematically examined by varying assembly conditions. It was found that the close-packed SiO2 monolayer yielded a maximum relative efficiency enhancement of 9.35%. Combining simulation and macro/micro optical measurements, we attributed the enhancement to the nanosphere-induced concentration and anti-reflection of incident light. The proposed self-assembly strategy provides a facile and cost-effective approach for engineering nanomaterials at 3D interfaces.

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