ELECTROREFLECTANCE CHARACTERIZATION OF THE Ge/Si GROOVE ISLAND STRUCTURES

2003 ◽  
Vol 02 (04n05) ◽  
pp. 369-373
Author(s):  
YO-YU CHEN ◽  
S. C. LIN ◽  
C. R. LU ◽  
C. T. CHIA ◽  
H. H. CHANG
Keyword(s):  
Optical Properties ◽  
Quantum Confinement ◽  
Transition Energy ◽  
Quantum Confinement Effect ◽  
Three Dimensional ◽  
Optical Transitions ◽  
Wetting Layer ◽  
Dimensional Growth ◽  
Electroreflectance Spectroscopy

The optical properties of Ge/Si groove island structures were investigated by the electroreflectance spectroscopy at various temperatures. Optical transitions involving the groove islands near the spectral range of 2~2.5 eV were observed. When the Ge growth temperature is decreased, the three-dimensional growth of the Ge island on the wetting layer is suppressed and the Ge/Si intermixing formation of stacking grooves in the Si layers is enhanced. The corresponding spectral intensity is increased and the transition energy is reduced due to the quantum confinement effect.

scholarly journals Synthesis and characterization of N, O-donor Schiff base capped ZnS NPs as a sensor for fluorescence selective detection of Fe 3+, Cr 2+ and Cd 2+ ions

2018 ◽  
Vol 4 (4) ◽  
pp. 151-162
Author(s):  
Dasari Ayodhya ◽  
Guttena Veerabhadram
Keyword(s):  
Schiff Base ◽  
Quantum Confinement ◽  
Metal Ion ◽  
Quantum Confinement Effect ◽  
Precipitation Method ◽  
Donor Ligand ◽  
Zinc Sulfide Nanoparticles ◽  
Co Precipitation ◽  
Selective Sensor

We report the simple synthesis of zinc sulfide nanoparticles (ZnSNPs) by a co-precipitation method using Schiff base, (2-[(4-methoxy-phenylimino)-methyl]-4-nitro phenol) as a capping agent. Here, Schiff base is also used as N, O-donor ligand to control the morphology of NPs and fluorescence interactions. The formation of ZnSNPs and their optical, structural, thermal properties and morphologies were studied by means of UV–vis DRS, fluorescence, FTIR, XRD, SEM, TEM, zeta potential and TGA. The optical properties and quantum confinement effect of the products were confirmed by means of spectroscopic measurements. XRD and TEM image shows that the synthesized ZnSNPs have cubic structures with a diameter of about less than 10 nm. The prepared ZnSNPs exhibited as a selective probe detection of Fe3+, Cr2+ and Cd2+ ions by fluorometrically and the emission band which disappears in the presence of increasing concentrations of Fe3+, Cr2+ and Cd2+ ions. Based on the fluorescence quenching of the NPs in the presence of metal ion of interest, the feasibility of their determinations was examined according to the Stern-Volmer equation. Our work suggested that Schiff base capped ZnSNPs could be a potential selective sensor in the detection of heavy metal ions.

scholarly journals Strong Quantum Confinement Effect in the Optical Properties of Ultrathin α-In2Se3

2016 ◽  
Vol 4 (12) ◽  
pp. 1939-1943 ◽  
Author(s):  
Jorge Quereda ◽  
Robert Biele ◽  
Gabino Rubio-Bollinger ◽  
Nicolás Agraït ◽  
Roberto D'Agosta ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Confinement Effect

Synthesis of Graphene-ZnO Heterogeneous Nanostructures by Chemical Vapor Deposition

2011 ◽  
Vol 1348 ◽  
Author(s):  
Jian Lin ◽  
Miroslav Penchev ◽  
Guoping Wang ◽  
Rajat K Paul ◽  
Jiebin Zhong ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Building Blocks ◽  
Zno Nanostructures ◽  
Large Area ◽  
Graphene Layers

ABSTRACTIn this work, we report the synthesis and characterization of three dimensional heterostructures graphene nanostructures (HGN) comprising continuous large area graphene layers and ZnO nanostructures, fabricated via chemical vapor deposition. Characterization of large area HGN demonstrates that it consists of 1-5 layers of graphene, and exhibits high optical transmittance and enhanced electrical conductivity. Electron microscopy investigation of the three dimensional heterostructures shows that the morphology of ZnO nanostructures is highly dependent on the growth temperature. It is observed that ordered crystalline ZnO nanostructures are preferably grown along the <0001> direction. Ultraviolet spectroscopy indicates that the CVD grown HGN layers has excellent optical properties. A combination of electrical and optical properties of graphene and ZnO building blocks in ZnO based HGN provides unique characteristics for opportunities in future optoelectronic devices.

Determination and Critical Assessment of the Optical Properties of Common Substrate Materials Used in III-V Nitride Heterostructures with Vacuum Ultraviolet Spectroscopic Ellipsometry

2001 ◽  
Vol 693 ◽  
Author(s):  
N.V. Edwards ◽  
O.P.A. Lindquist ◽  
L.D. Madsen ◽  
S. Zollner ◽  
K. Järrehdahl ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dielectric Function ◽  
Spectroscopic Ellipsometry ◽  
Optical Constants ◽  
Vacuum Ultraviolet ◽  
Critical Assessment ◽  
Optical Transitions ◽  
Common Substrate ◽  
Materials Used

AbstractAs a first step toward enabling the in-line metrology of III-V nitride heterostructure and materials, we present the optical constants of the two common substrate materials over an unprecendented spectral range. Vacuum Ultraviolet spectroscopic ellipsometry (VUVSE) was used to obtain the optical constants for Al2O3 and the ordinary and extra-ordinary component of the dielectric function for both 4H- and 6H-SiC. The results are discussed in the context of anisotropy, polytypism, bandstructure, optical transitions, and preparation/characterization of abrupt surfaces, where appropriate.

scholarly journals Tailoring Blue-Green Double Emissions in Carbon Quantum Dots via Co-Doping Engineering by Competition Mechanism between Chlorine-Related States and Conjugated π-Domains

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 635 ◽  
Author(s):  
Xue Sun ◽  
Huilian Liu ◽  
Lili Yang ◽  
Xinying Wang ◽  
Weiqiang Yang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Reaction Time ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Carbon Quantum Dots ◽  
Confinement Effect ◽  
Co Doping ◽  
Photoelectric Properties ◽  
Co Doped

Representing single-layer to tens of layers of graphene in a size less than 30 nm, carbon quantum dots (CQDs) is becoming an advanced multifunctional material for its unique optical, electronic, spin and photoelectric properties induced by the quantum confinement effect and edge effect. In present work, upon co-doping engineering, nitrogen and chlorine co-doped CQDs with uniquely strong blue-green double emissions are developed via a facile and one-pot hydrothermal method. The crystalline and optical properties of CQDs have been well manipulated by tuning the mole ratio of nitrogen/chlorine and the reaction time. The characteristic green emission centered at 512 nm has been verified, originating from the chlorine-related states, the other blue emissions centered at 460 nm are attributed to the conjugated π-domain. Increasing the proportion of 1,2,4-benzentriamine dihydrochloride can effectively adjust the bandgap of CQDs, mainly caused by the synergy and competition of chlorine-related states and the conjugated π-domain. Prolonging the reaction time promotes more nitrogen and chlorine dopants incorporate into CQDs, which inhibits the growth of CQDs to reduce the average size of CQDs down to 1.5 nm, so that the quantum confinement effect dominates into play. This work not only provides a candidate with excellent optical properties for heteroatoms-doped carbon materials but also benefits to stimulate the intensive studies for co-doped carbon with chlorine as one of new dopants paradigm.

Nanostructured crystals: An unprecedented class of hybrid semiconductors exhibiting structure-induced quantum confinement effect and systematically tunable properties

2017 ◽  
Author(s):  
Jing Li ◽  
Xiao-Ying Huang
Keyword(s):  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Three Dimensional ◽  
Hybrid Nanostructures ◽  
Confinement Effect ◽  
Design And Synthesis ◽  
Organic Hybrid ◽  
Expansion Behavior ◽  
Dimensional Network ◽  
Hybrid Semiconductors

This article describes the structure-induced quantum confinement effect in nanostructured crystals, a unique class of hybrid semiconductors that incorporate organic and inorganic components into a single-crystal lattice via covalent (coordinative) bonds to form extended one-, two- and three-dimensional network structures. These structures are comprised of subnanometer-sized II-VI semiconductor segments (inorganic component) and amine molecules (organic component) arranged into perfectly ordered arrays. The article first provides an overview of II-VI and III-V semiconductors, II-VI colloidal quantum dots, inorganic-organic hybrid materials before discussing the design and synthesis of I-VI-based inorganic-organic hybrid nanostructures. It also considers the crystal structures, quantum confinement effect, bandgaps, and optical properties, thermal properties, thermal expansion behavior of nanostructured crystals.

Synthesis and Characterization of High Quality InN Nanowires and Nano-networks

2007 ◽  
Vol 1058 ◽  
Author(s):  
Zhihua Cai ◽  
Samir Garzon ◽  
Richard A. Webb ◽  
Goutam Koley
Keyword(s):  
Fast Rate ◽  
Three Dimensional ◽  
Catalyst Layer ◽  
Direct Reaction ◽  
Si Substrate ◽  
Large Area ◽  
High Quality ◽  
Dimensional Growth ◽  
Quartz Tube Furnace

ABSTRACTHigh quality InN nanowires have been synthesized in a horizontal quartz-tube furnace through direct reaction between metallic Indium and Ammonia using Nitrogen as the carrier gas. Thin film of Au on SiO2/Si substrate has been used as the catalyst layer, facilitating vapor-liquid-solid growth of the nanostructures. The nanowires were grown at a very fast rate of up to 30 μm/hr. Smooth and horizontal nanowire growth was achieved only with nanoscale catalyst patterns, while large area catalyst coverage resulted in uncontrolled and three-dimensional growth. The InN nanowires, which were usually covered with a thin shell layer of In2O3, grew along [110] direction, with overall diameters 20 - 60 nm and lengths 5 - 15 μm. The synthesized nanowires bent spontaneously or got deflected from other nanowires at multiples of 30 degrees forming nano-networks. The catalyst particles for the NWs were found mostly at the sides of the NW apex which helped them to bend spontaneously or get deflected from other NWs at angles which were multiples of 30 degrees. The NW based FETs with a back-gated configuration have already been investigated. The gate-bias dependent mobility of the NWs ranged from 55 cm2/Vs to 220 cm2/Vs, and their carrier concentration was ∼1018 cm−3.

Properties of Nanostructure Formed on SiO2/Si Interface by Laser Radiation

2007 ◽  
Vol 131-133 ◽  
pp. 559-562 ◽  
Author(s):  
Arthur Medvid ◽  
Igor Dmitruk ◽  
Pavels Onufrijevs ◽  
Iryna Pundyk
Keyword(s):  
Optical Properties ◽  
Laser Radiation ◽  
Band Gap ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Confinement Effect ◽  
Visible Range ◽  
Pulsed Nd:Yag Laser ◽  
Self Organized ◽  
Graded Band Gap

The aim of this work is to study optical properties of Si nanohills formed on the SiO2/Si interface by the pulsed Nd:YAG laser radiation. Nanohills which are self-organized on the surface of Si, are characterized by strong photoluminescence in the visible range of spectra with long wing in the red part of spectra. This peculiarity is explained by Quantum confinement effect in nanohillsnanowires with graded diameter. We have found a new method for graded band gap semiconductor formation using an elementary semiconductor. Graded change of band gap arises due to Quantum confinement effect.

The role of surface vibrations and quantum confinement effect to the optical properties of very thin nanocrystalline silicon films

2007 ◽  
Vol 102 (8) ◽  
pp. 083534 ◽  
Author(s):  
Emmanouil Lioudakis ◽  
Antreas Antoniou ◽  
Andreas Othonos ◽  
Constantinos Christofides ◽  
A. G. Nassiopoulou ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Nanocrystalline Silicon ◽  
Silicon Films ◽  
Confinement Effect ◽  
Surface Vibrations ◽  
Nanocrystalline Silicon Films

GROWTH AND CHARACTERIZATION OF CdS AND CdS:Ag LUMINESCENT QUANTUM DOTS DISPERSED IN SOLUTION

2010 ◽  
Vol 24 (25) ◽  
pp. 2591-2599 ◽  
Author(s):  
M. H. YOUSEFI ◽  
A. A. ABDOLHOSSEINZADEH ◽  
H. R. FALLAH ◽  
A. A. KHOSRAVI
Keyword(s):  
Quantum Confinement ◽  
High Stability ◽  
Colloidal Solution ◽  
Quantum Confinement Effect ◽  
Green Emission ◽  
Capping Agent ◽  
Luminescent Nanoparticles ◽  
Xrd Patterns ◽  
Luminescent Quantum Dots

A fast-chemically capping method in aqueous solution was developed to synthesize CdS and CdS : Ag luminescent nanoparticles and particles with sizes between 2–4 nm. The achieving of well-dispersed and narrow-sized particles in colloidal solution and also, high stability of them using mercaptoethanol (ME) as a capping agent was established. Quantum confinement effect was observed in UV-vis absorption as well as in PL spectra. PL spectroscopy also showed green emission and Ag dopants caused a faster energy transfer between CdS inter-bands. XRD patterns exhibited that both cubic and hexagonal phases exist in solutions. Ultimately, TEM images captured from QDs displayed the shapes of nanoclusters which are almost spherical.

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