Nucleation and Stochiometry Dependence of Rutile-TiO2(001)/GaN(0001) Thin Films Grown by Plasma-Assisted Molecular Beam Epitaxy

2008 ◽  
Vol 1108 ◽  
Author(s):  
Costel Constantin ◽  
kai sun ◽  
Randall M Feenstra
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Initial Nucleation

AbstractIn this work we explore both the initial nucleation and the stoichiometry of rutile-TiO2(001) grown on wurtzite GaN(0001) by radio-frequency O2-plasma molecular beam epitaxy. Two studies are performed; in the first, the dependence of the growth on stoichiometry (Ti-rich and O-rich) is observed using reflection high energy electron diffraction and high resolution transmission electron microscopy. In the second study we examine the effect of different initial nucleation surfaces (i.e. Ga-terminated and excess Ga-terminated) and compare the interfaces and bulk crystallinity of the TiO2(001) films grown on top of these surfaces. High-resolution transmission electron microscopy and x-ray diffraction measurements show a better interface for TiO2(001)/Ga-terminated - GaN(0001) as compared to the TiO2(001)/excess Ga-terminated- GaN(0001).

Double Periodicity Formation in EuTe/PbTe Superlattices

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Shima ◽  
L. Salamanca-Riba ◽  
G. Springholz ◽  
G. Bauer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices

ABSTRACTMolecular beam epitaxy was used to grow EuTe(x)/PbTe(y) short period superlattices with x=1-4 EuTe(111) monolayers alternating with y≈3x PbTe monolayers. The superlattices were characterized by transmission electron microscopy and high resolution x-ray diffraction. Regions with double periodicity were observed coexisting with areas of nominal periodicity. The sample with x=3.5 and y=9, for example, contains regions with double periodicity of x=7 and y=17. X-ray diffraction measurements confirm the formation of the double periodicity in these samples by the appearance of weak satellites in between the satellites of the nominal periodicity. The double periodicity in the superlattice is believed to result from interdiffusion during the growth. A model for this process is presented.

Nanoscale Ge1−xMnxTe ferromagnetic semiconductors

2017 ◽  
Author(s):  
J.F. Bi ◽  
K.L. Teo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam ◽  
Anomalous Hall Effect ◽  
Ferromagnetic Semiconductors ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Skew Scattering

This article discusses the structure characterizations, magnetic and transport behaviors of the nanoscale ferromagnetic semiconductors Ge1-xMnxTe grown by molecular beam epitaxy with various manganese compositions x ranging from 0.14 to 0.98. After providing an overview of the growth procedure and characterization, the article analyzes the structures of the Ge1-xMnxTe system using X-ray diffraction and high-resolution transmission electron microscopy. It then considers the optical, magnetic and transport properties of the semiconductors and shows that the crystal quality is degraded and the proportion of amorphous phase increases with increasing Mn composition. Nanoclusters and nanoscale grains can be observed when x > 0.24, which greatly affect their magnetic and electronic properties. The magnetic anisotropy is weakened due to different orientations of the clusters embedded in the GeTe host. An anomalous Hall effect is also observed in the samples, which can be attributed to extrinsic skew scattering.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Vertical self-organization of Ge1−xMnx nanocolumn multilayers grown on Ge(001) substrates

2016 ◽  
Vol 30 (20) ◽  
pp. 1650269 ◽  
Author(s):  
Thi Giang Le ◽  
Minh Tuan Dau
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Elastic Constant ◽  
Structural Properties ◽  
Molecular Beam ◽  
Self Organization ◽  
Transmission Electron ◽  
2D Model

High-resolution transmission electron microscopy (HR-TEM) has been used to investigate the structural properties of GeMn/Ge nanocolumns multilayer samples grown on Ge(001) substrates by means of molecular beam epitaxy (MBE) system. Four bilayers with the spacer thickness in the range between 6 nm and 15 nm and 10 periods of bilayers of Ge[Formula: see text]Mn[Formula: see text]/Ge nanocolumn are presented. A simplified 2D model based on the theory of elastic constant interactions has been used to provide reasonable explanations to the vertical self-organization of GeMn nanocolumns in multilayers.

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