Alloying Buffer Layers in Colloidal CdSe/ZnS Core/Shell Nanocrystals

2014 ◽  
Vol 67 (6) ◽  
pp. 844
Author(s):  
Huichao Zhang ◽  
Yonghong Ye ◽  
Boping Yang ◽  
Li Shen ◽  
Yiping Cui ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Lattice Mismatch ◽  
Buffer Layers ◽  
Temperature Dependent ◽  
Spectroscopy Analysis ◽  
Cdse Core ◽  
Time Resolved ◽  
X Ray ◽  
Large Lattice ◽  
Large Lattice Mismatch

When a ZnS shell is coated onto a CdSe core, some non-radiative defects are formed with the relaxation of the strain induced by the large lattice mismatch between CdSe and ZnS even though there are Zn0.5Cd0.5Se or ZnSe buffer layers, as indicated by the decrease of photoluminescent (PL) quantum yield and the reverse evolution of temperature-dependent time-resolved PL decay. X-Ray photoelectron spectroscopy analysis reveals that these defects are induced by the formation of an interfacial alloy during the epitaxy process. These defects could be significantly suppressed if the ZnxCd1–xSeyS1–y alloy buffer layer is artificially introduced.

Highly Mismatched Hetero-Epitaxial Growth of Cubic Sic on Si

1987 ◽  
Vol 97 ◽  
Author(s):  
Hiroyuki Matsunami
Keyword(s):  
Epitaxial Growth ◽  
Lattice Mismatch ◽  
Electronic Devices ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
Optimum Conditions ◽  
Large Lattice ◽  
Impurity Doping ◽  
Large Lattice Mismatch

ABSTRACTSingle crystals of cubic SiC were hetero-epitaxially grown on Si by chemical vapor deposition (CVD) method. A carbonized buffer layer on Si is utilized to overcome the large lattice mismatch of 20 %. Optimum conditions to make the buffer layers and those structures are discussed. Crystal quality of the CVD grown cubic SiC is analyzed by using X-ray analyses and microscopic observations. Electrical properties controlled by impurity doping during epitaxial growth are described together with fundamental electronic devices.

Growth and properties of epitaxial PbSe on Si(111) and Si(100) without buffer layer

1995 ◽  
Vol 379 ◽  
Author(s):  
P. Müller ◽  
A.N. Tiwari ◽  
H. Zogg
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Infrared Detector ◽  
Device Fabrication ◽  
Buffer Layers ◽  
Silicon Substrates ◽  
High Quality ◽  
Si Substrates ◽  
Large Lattice ◽  
Large Lattice Mismatch

Narrow gap IV-VI materials like PbS, PbSnSe and PbSnTe are used for infrared detector device fabrication [1,2]. Earlier an intermediate Ila-fluoride buffer layer, which consisted of a BaF2/CaF2-stack of about 2000 Å thickness, was used to get epitaxial high quality layers on silicon substrates. This buffer is now reduced to a much thinner layer of only about 20 Å thick CaF2, regardless the large lattice mismatch between layer and substrate [3,4,5]. The question therefore arises if high quality IV-VI layers can be grown on Si-substrates without any buffer layer as e.g. in CdTe/Si or GaAs/Si systems.The aim of this work is to grow IV-VI layers directly on Si-substrates without any buffer layers to study the growth kinetics and epitaxial quality. PbSe was chosen as a representant of IV-VI materials, and layers were grown on (111)- and (100)-oriented silicon substrates.

Epitaxial Growth of Thick Ag/Si(111) Films

1987 ◽  
Vol 102 ◽  
Author(s):  
K.-H. Park ◽  
H.-S. Jin ◽  
L. Luo ◽  
W.M. Gibson ◽  
G.-C. Wang ◽  
...  
Keyword(s):  
Pole Figure ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Rutherford Backscattering Spectrometry ◽  
Twin Structure ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Large Lattice ◽  
Axial Channeling ◽  
Large Lattice Mismatch

ABSTRACT600∼4000Å thick Ag films grown on 3∼4· misoriented Si(111) substrates by molecular beam epitaxy (MBE) technique have been studied by using x-ray pole-figure analysis and MeV He+ Rutherford Backscattering Spectrometry (RBS)/channeling technique. X-ray pole-figure measurements revealed that despite the large lattice mismatch (∼25%) between Ag and Si, Ag films with epitaxial relationship Ag(111)//Si(111):Ag[011]//Si[011] were grown with a small quantity (15∼20%) of twin structure. The <111> axial channeling minimum yield (Xmin) is reduced at the Ag surface as the Ag film thickness increases. These films were thermally stable up to 500°C annealing but the twinning disappeared after annealing

Structural Studies of an InAs-GaAs Superlattice Alloy

1985 ◽  
Vol 47 ◽  
Author(s):  
M. C. Tamargo ◽  
R. Hull ◽  
L. H. Greene ◽  
J. R. Hayes ◽  
N. Tabatabaie ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Layer Structure ◽  
Growth Conditions ◽  
Buffer Layers ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Strained Layer Superlattices ◽  
Lattice Matched

ABSTRACTThin alternating layers of InAs and GaAs have been grown by MBE on buffer layers lattice matched to InP. The layer structure was evaluated by transmission electron microscopy (TEM) and low angle X-ray scattering. Commensurate epitaxial layers approximately 15Å thick were obtained in spite of the large lattice mismatch (7%). These results and their implication for growth conditions of strained-layer superlattices will be discussed.

Heteroepitaxial growth and structural analysis of epitaxial α–Fe2O3(1010) on TiO2(001)

2005 ◽  
Vol 20 (5) ◽  
pp. 1250-1256 ◽  
Author(s):  
Joshua R. Williams ◽  
Chongmin Wang ◽  
Scott A. Chambers
Keyword(s):  
Lattice Mismatch ◽  
High Energy ◽  
Unit Cell ◽  
Heteroepitaxial Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Pole Figures ◽  
Large Lattice ◽  
Large Lattice Mismatch

We grew epitaxial α–Fe2O3(1010) on TiO2(001) rutile by oxygen plasma-assisted molecular-beam epitaxy. High-resolution transmission electron microscopy (HRTEM), reflection high-energy electron diffraction (RHEED), and x-ray diffraction pole figures confirm that the film is composed of four different in-plane orientations rotated by 90° relative to one another. For a given Fe2O3 unit cell, the lattice mismatch along the parallel [0001]Fe2O3 and [100]TiO2 directions is nominally +67%. However, due to a 3-fold repetition of the slightly distorted square symmetry of anion positions within the Fe2O3 unit cell, there is a coincidental anion alignment along the [0001]Fe2O3 and [100]TiO2 directions, which results in an effective lattice mismatch of only −0.02% along this direction. The lattice mismatch is nearly 10% in the orthogonal [1120]Fe2O3 and [100]TiO2 directions. The film is highly ordered and well registered to the substrate despite a large lattice mismatch in one direction. The film grows in registry with the substrate along the parallel [0001]Fe2O3 and [100]TiO2 directions and nucleates dislocations along the orthogonal [1120]Fe2O3 [100]TiO2 directions.

Structures of Silver/Cobalt Metallic Superlattice and Changes Due to Annealing

1990 ◽  
Vol 187 ◽  
Author(s):  
T. Kingetsu ◽  
K. Sakai ◽  
T. Kaneko ◽  
A. Yamaguchi ◽  
R. Yamamoto
Keyword(s):  
Magnetic Anisotropy ◽  
Growth Temperature ◽  
Lattice Mismatch ◽  
Buffer Layers ◽  
Ex Situ ◽  
Superlattice Structure ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Fcc Structure

AbstractAg/Co metallic superlattices were grown onto Ag buffer layers pre-deposited on sapphire or MgO substrates by ultrahigh vacuum alternate deposition technique. In-situ RHEED observations during superlattice growth and ex-situ XRD measurements revealed that structures of the superlattices were strongly affected by the condition of Ag buffer layer preparation. In case where the Ag buffer layers were single crystals with smooth (111) surfaces, Co layers were epitaxially grown on the buffer layers even in the presence of large lattice mismatch, and whole the superlattices were grown with an epitaxial relation. Interface smoothness was strongly related to the growth temperature. Spotty RHEED patterns of Co layers for a low growth temperature indicated that the Co layers had an FCC structure. Post-annealing of the samples, in some cases, destroyed a superlattice structure completely. From relations between magnetic anisotropy and Co-layer thickness obtained with VSM measurements, it was found that Ag/Co superlattice exhibited in-plane magnetic anisotropy down to a Co thickness of 4A and that the anisotropy was correlated with roughness of the interfaces.

Growth of Hexagonal Gallium Nitride Films On The (111) Surfaces of Silicon with Zinc Oxide Buffer Layers

1996 ◽  
Vol 449 ◽  
Author(s):  
Y. Kim ◽  
C. G. Kim ◽  
K-W. Lee ◽  
K-S. Yu ◽  
J. T. Park ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Gallium Nitride ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
High Energy ◽  
Buffer Layers ◽  
X Ray

ABSTRACTThe growth of gallium nitride films on sapphire substrates has not been straightforward because of the large lattice mismatch between gallium nitride and sapphire. Zinc oxide is structurally the closest material to gallium nitride and therefore is finding use as the substrate for gallium nitride. Single crystal wafers of zinc oxide are hard to obtain and very expensive. However, a thin layer of zinc oxide on a suitable substrate might solve this problem. In this work, highly c-axis oriented zinc oxide buffer layers were grown on Si(lll) substrates at temperatures 410–540 °C by chemical vapor deposition of bis(2,2,6,6-tetramethyl–3,5-heptanedionato)zinc, Zn(tmhd)2, and the hexagonal GaN films were subsequently deposited on them at 500 °C using the single precursor tris(diethyl -μ-amido-gallium), [(C2H5)2 GaNH2]3. The compound Zn(tmhd)2 was found to require oxygen for the deposition of zinc oxide. In the case of gallium nitride, low pressure chemical vapor deposition of tris(diethyl-μ-amido-gallium) worked reasonably well with or without a carrier gas. The buffer layers and the GaN films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and reflection high energy elctron diffraction (RHEED).

scholarly journals Enhanced luminescence/photodetecting bifunctional devices based on ZnO:Ga microwire/p-Si heterojunction by incorporating Ag nanowires

2021 ◽  
Author(s):  
Mingming Jiang ◽  
Yang Liu ◽  
Ruiming Dai ◽  
Kai Tang ◽  
Peng Wan ◽  
...  
Keyword(s):  
Band Gap ◽  
Carrier Mobility ◽  
Lattice Mismatch ◽  
Semiconductor Materials ◽  
Large Lattice ◽  
Ag Nanowires ◽  
Large Lattice Mismatch ◽  
Enhanced Luminescence ◽  
Indirect Band Gap

Suffering from the indirect band gap, low carrier mobility, and large lattice mismatch with other semiconductor materials, one of the current challenges in Si-based materials and structures is to prepare...

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