scholarly journals A Novel Method to Grow Vertically Aligned Silicon Nanowires on Si (111) and Their Optical Absorption

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Tzuen-Wei Ho ◽  
Franklin Chau-Nan Hong
Keyword(s):  
Silicon Nanowires ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Process Conditions ◽  
Vertical Alignment ◽  
Cooling Process ◽  
Surface Reflection ◽  
Vertically Aligned ◽  
Novel Method ◽  
High Degree

In this study we grew silicon nanowires (SiNWs) on Si (111) substrate by gold-catalyzed vapor liquid solid (VLS) process using tetrachlorosilane (SiCl4) in a hot-wall chemical vapor deposition reactor. SiNWs with 150–200 nm diameters were found to grow along the orientations of all〈111〉family, including the vertical and the inclined, on Si (111). The effects of various process conditions, including SiCl4concentration, SiCl4feeding temperature, H2annealing, and ramp cooling, on the crystal quality and growth orientation of SiNWs, were studied to optimize the growth conditions. Furthermore, a novel method was developed to reliably grow vertically aligned SiNWs on Si (111) utilizing the principle of liquid phase epitaxy (LPE). A ramp-cooling process was employed to slowly precipitate the epitaxial Si seeds on Si (111) after H2annealing at 650°C. Then, after heating in SiCl4/H2up to 850°C to grow SiNWs, almost 100% vertically aligned SiNWs could be achieved reproducibly. The high degree of vertical alignment of SiNWs is effective in reducing surface reflection of solar light with the reflectance decreasing with increasing the SiNWs length. The vertically aligned SiNWs have good potentials for solar cells and nano devices.

Synthesis of Silicon Nanowires and their Heterostructures by Thermal Chemical Vapor Deposition

2005 ◽  
Vol 879 ◽  
Author(s):  
Woo-Sung Jang ◽  
Seung Yong Bae ◽  
Jeunghee Park
Keyword(s):  
Silicon Nanowires ◽  
Chemical Vapor ◽  
Average Diameter ◽  
Growth Conditions ◽  
Nitride Layer ◽  
Growth Direction ◽  
Thermal Reaction ◽  
Si Nanowires ◽  
Oxide Mixture ◽  
Thermal Chemical Vapor Deposition

AbstractThe Si nanowires were synthesized using a novel catalytic thermal reaction under Ar flow. The average diameter is in the range of 50 ∼ 100 nm. They consist of defect-free single-crystalline cubic structure with the [111] growth direction. The thickness of amorphous oxide outer layers was controllable by growth conditions or surface treatment. In order to protect the oxidation, the Si nanowires were coated with boron nitride layer by the reaction of boron oxide mixture with NH3.

Novel method for carbon nanotube growth using vapor-phase catalyst delivery

2020 ◽  
Vol 13 (05) ◽  
pp. 2050026
Author(s):  
Takayuki Nakano ◽  
Takahiro Kikuchi ◽  
Yuki Usuda ◽  
Yoku Inoue
Keyword(s):  
Vapor Phase ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Catalyst Precursor ◽  
Synthesis Conditions ◽  
Hcl Gas ◽  
Catalyst Formation ◽  
Novel Method ◽  
Carbon Nanotube Growth ◽  
Nanotube Growth

In this study, we demonstrated a novel method to grow carbon nanotubes (CNTs) by chloride-mediated chemical vapor deposition with hydride vapor-phase nucleated catalyst (HVPN). In the HVPN method, FeCl2 as a catalyst precursor was produced by an in situ chemical reaction between Fe powder and HCl gas. After the synthesis of FeCl2, CNTs were grown by supplying acetylene. We studied growth conditions for the catalyst formation process in HVPN method. High-quality CNT forests were grown by optimizing the FeCl2 synthesis conditions. This study has established the HVPN method as a novel, highly controllable way to grow CNT forests.

Growth of Ruthenium and Ruthenium oxide nanoplates

2011 ◽  
Vol 1309 ◽  
Author(s):  
Lamartine Meda ◽  
Geoffrey D. Stevens
Keyword(s):  
Indium Tin Oxide ◽  
Ruthenium Oxide ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Coated Glass Substrate ◽  
X Ray ◽  
Average Area ◽  
Continuous Layer ◽  
Vertically Aligned

ABSTRACTBy carefully manipulating and controlling the growth conditions, Ruthenium (Ru) and ruthenium oxide (RuO2) two-dimensional (2-D) nanostructure were self-assembled into a stack of plates on indium tin oxide coated glass substrate. The nanoplates were grown in a horizontal hot-wall metalorganic chemical vapor deposition (MOCVD) from ruthenocene. Each nanoplate has a thickness in the range of 25 - 60 nm and the average area is 1000 x 300 nm2. Each stack of nanoplates is approximately 1.2 m in height. A continuous layer of Ru and RuO2 thin film, which may serve as the growth template, is observed on the bottom of the nanoplate stacks. Field-emission scanning electron microscopy reveals that each stack of nanoplates was grown vertically aligned on the substrate and exhibited elongated shape. Structural properties which were examined by X-ray diffraction show that the nanoplates are polycrystalline.

Combined Structural and Optical Assessment of CVD Grown 3C-SiC/Si

1994 ◽  
Vol 339 ◽  
Author(s):  
Z. C. Feng ◽  
C. C. Tin ◽  
K. T. Yue ◽  
R. Hu ◽  
J. Williams ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Growth Conditions ◽  
Growth Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Perfection ◽  
Cvd Growth ◽  
Torr Pressure ◽  
High Degree ◽  
Sic Films

ABSTRACTA combined structural and optical assessment of cubic (3C-) SiC thin films grown on Si (100) substrates by chemical vapor epitaxy (CVD) is presented. The CVD growth was performed at both atmospheric and low (100 Torr) pressure, using a vertical reactor. The CVD-grown 3C-SiC films with different growth time were characterized by X-ray diffraction, Raman scattering and Fourier transform infrared (FTIR) spectroscopy to be single crystalline with a high degree of crystal perfection. The film thickness was determined from FTIR spectra. Variations of X-ray, FTIR and Raman spectra with different growth conditions and film thicknesses are studied comparatively. Related problems are discussed.

Patterning Anodic Porous Alumina with Resist Developers for Patterned Nanowire Formation

2015 ◽  
Vol 1785 ◽  
pp. 13-18 ◽  
Author(s):  
SeungYeon. Lee ◽  
Daniel Wratkowski ◽  
Jeong-Hyun Cho
Keyword(s):  
Silicon Nanowires ◽  
Porous Alumina ◽  
Chemical Vapor ◽  
Initial Step ◽  
Metal Substrate ◽  
Nanowire Arrays ◽  
Anodic Porous Alumina ◽  
Anodization Process ◽  
Vertically Aligned ◽  
Al Thin Film

ABSTRACTFormation of patterned metal and semiconductor (e.g. silicon) nanowires is achieved using anodic aluminum oxide (AAO) templates with porous structures of different heights resulting from an initial step difference made by etching the aluminum (Al) thin film with a photoresist developer prior to the anodization process. This approach allows for the growth of vertically aligned nanowire arrays on a metal substrate, instead of an oriented semiconductor substrate, using an electroplating or a chemical vapor deposition (CVD) process. The vertically aligned metal and semiconductor nanowires defined on a metal substrate could be applied to the realization of vertical 3D transistors, field emission devices, or nano-micro sensors for biological applications.

TEM study of very thin InGaAsP layers grown by liquid-phase epitaxy

1990 ◽  
Vol 48 (4) ◽  
pp. 672-673
Author(s):  
N.A. Bert ◽  
A.O. Kosogov
Keyword(s):  
Liquid Phase ◽  
Liquid Phase Epitaxy ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Dark Field ◽  
Organic Chemical ◽  
Simple Liquid ◽  
Cross Sectional ◽  
Conventional Procedure ◽  
Double Heterostructures

The very thin (<100 Å) InGaAsP layers were grown not only by molecular beam epitaxy and metal-organic chemical vapor deposition but recently also by simple liquid phase epitaxy (LPE) technique. Characterization of their thickness, interfase abruptness and lattice defects is important and requires TEM methods to be used.The samples were InGaAsP/InGaP double heterostructures grown on (111)A GaAs substrate. The exact growth conditions are described in Ref.1. The salient points are that the quarternary layers were being grown at 750°C during a fast movement of substrate and a convection caused in the melt by that movement was eliminated. TEM cross-section specimens were prepared by means of conventional procedure. The studies were conducted in EM 420T and JEM 4000EX instruments.The (200) dark-field cross-sectional imaging is the most appropriate TEM technique to distinguish between individual layers in 111-v semiconductor heterostructures.

scholarly journals Employing entropy measures to identify visitors in multi-occupancy environments

2020 ◽  
Author(s):  
Aadel Howedi ◽  
Ahmad Lotfi ◽  
Amir Pourabdollah
Keyword(s):  
Home Environment ◽  
Daily Living ◽  
Wearable Sensors ◽  
Permutation Entropy ◽  
Care Workers ◽  
Entropy Measures ◽  
Novel Method ◽  
High Degree ◽  
Motion Detectors ◽  
To Receive

AbstractHuman activity recognition (HAR) is used to support older adults to live independently in their own homes. Once activities of daily living (ADL) are recognised, gathered information will be used to identify abnormalities in comparison with the routine activities. Ambient sensors, including occupancy sensors and door entry sensors, are often used to monitor and identify different activities. Most of the current research in HAR focuses on a single-occupant environment when only one person is monitored, and their activities are categorised. The assumption that home environments are occupied by one person all the time is often not true. It is common for a resident to receive visits from family members or health care workers, representing a multi-occupancy environment. Entropy analysis is an established method for irregularity detection in many applications; however, it has been rarely applied in the context of ADL and HAR. In this paper, a novel method based on different entropy measures, including Shannon Entropy, Permutation Entropy, and Multiscale-Permutation Entropy, is employed to investigate the effectiveness of these entropy measures in identifying visitors in a home environment. This research aims to investigate whether entropy measures can be utilised to identify a visitor in a home environment, solely based on the information collected from motion detectors [e.g., passive infra-red] and door entry sensors. The entropy measures are tested and evaluated based on a dataset gathered from a real home environment. Experimental results are presented to show the effectiveness of entropy measures to identify visitors and the time of their visits without the need for employing extra wearable sensors to tag the visitors. The results obtained from the experiments show that the proposed entropy measures could be used to detect and identify a visitor in a home environment with a high degree of accuracy.

Growth of GaN without Yellow Luminescence

1995 ◽  
Vol 395 ◽  
Author(s):  
X. Zhang ◽  
P. Kung ◽  
D. Walker ◽  
A. Saxler ◽  
M. Razeghi
Keyword(s):  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Deep Level ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Native Defect ◽  
Yellow Luminescence ◽  
Gallium Vacancy ◽  
Rich Condition

ABSTRACTWe report the growth and photoluminescence characterization of GaN grown on different substrates and under different growth conditions using metalorganic chemical vapor deposition. The deep-level yellow luminescence centered at around 2.2eV is attributed to native defect, most possibly the gallium vacancy. The yellow luminescence can be substantially reduced By growing GaN under Ga-rich condition or doping GaN with Ge or Mg.

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