Modification of InN Properties by Interactions with Hydrogen and Nitrogen

2005 ◽  
Vol 892 ◽  
Author(s):  
Maria Losurdo ◽  
Maria Michela Giangregorio ◽  
Giovanni Bruno ◽  
Tong-Ho Kim ◽  
Pae Wu ◽  
...  
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Beam ◽  
Morphological Changes ◽  
Epitaxial Films ◽  
Intensity Increase ◽  
Force Microscopy ◽  
Atomic Force ◽  
Peak Energy ◽  
Hall Effect Measurements ◽  
The Impact

AbstractThe interaction of InN epitaxial films grown by r.f. plasma assisted molecular beam epitaxy with atomic hydrogen and nitrogen, produced by remote r.f. H2 and N2 plasmas, is investigated. InN strongly reacts with both atomic hydrogen and nitrogen yielding depletion of nitrogen and concurrent formation of In clusters. The impact of hydrogen treatments on the optical properties of InN is assessed using photoluminescence (PL). It is found that hydrogen suppresses the intense PL band peaked at approximately 0.7eV for the as-grown InN epitaxial layers, and results in the appearance of a new PL band whose peak energy and intensity increase with H-dose. The effect of exposure to atomic hydrogen and nitrogen on electrical properties of InN is investigated using Hall effect measurements. Atomic force microscopy is also used for studying the morphological changes of InN upon interaction with atomic hydrogen and nitrogen.

scholarly journals Deswelling Induced Morphological Changes in Dual pH and Temperature Responsive Ultra-Low Crosslinked Poly (N-Isopropyl Acrylamide)-Co-Acrylic Acid Microgels

2018 ◽  
Author(s):  
Molla Islam ◽  
Maddie Tumbarello ◽  
Andrew Lyon
Keyword(s):  
Light Scattering ◽  
Acrylic Acid ◽  
Morphological Changes ◽  
Scattering Data ◽  
Ionization State ◽  
Force Microscopy ◽  
Temperature Responsive ◽  
Atomic Force ◽  
Isopropyl Acrylamide ◽  
The Impact

<div>We demonstrated the deswelling induced morphological change in dual pH and Temperature responsive ultra-low crosslinked Poly (N-isopropyl acrylamide)-co-acrylic acid microgels. The responsivity with pH and temperature were studied by light scattering and atomic force microscopy. Light scattering data suggest that at pH 4.5 the microgels undergo multiple transitions associated with collapse of pNIPAm-rich segments and repulsion between the AAc-rich segments. The evolution of punctate structures around the periphery or throughout the whole microgels at pH 4.5 and 6.5 respectively was revealed by AFM, further illustrating the heterogeneous deswelling present in the ionized copolymer microgels.</div><div>The impact of this study and understanding how ionization state of copolymer dictates the overall structural properties of microgels will widen our understanding for their applications in biotechnology</div><div><b><br></b></div>

Epitaxial Growth and Characterization of NbxTi1−xO2 Rutile Films by Oxygen-Plasma-Assisted Molecular Beam Epitaxy

1995 ◽  
Vol 401 ◽  
Author(s):  
Y. Gao ◽  
S. A. Chambers
Keyword(s):  
Molecular Beam Epitaxy ◽  
Photoelectron Spectroscopy ◽  
Oxygen Plasma ◽  
Molecular Beam ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Force Microscopy ◽  
Atomic Force

AbstractEpitaxial films of NbxTi1−xO2 rutile were grown on TiO2 (110) and (100) at 600 °C by oxygen-plasma-assisted molecular beam epitaxy using elemental Ti and Nb sources. The epitaxial films were characterized by means of reflection high-energy and low-energy electron diffraction (RHEED/LEED), x-ray photoelectron spectroscopy and diffraction (XPS/XPD), ultraviolet photoemission spectroscopy (UPS) and atomic force microscopy (AFM). The epitaxial films grow in a layer-by-layer fashion and have excellent short- and long-range structure order at x≤0.3 on TiO2(110) and at x≤0.15 on TiO2(100). However, the epitaxial films become rough and disorder at higher doping levels. Nb substitutionally incorporates at cation lattice sites, leading to NbxTi1−xO2 solid solutions. In addition, the oxidation state of Nb in the NbxTi1−xO2 films has been determined to be +4.

Impact of the LED-based light source working regime on the degradation of polymethyl methacrylate

2019 ◽  
Vol 52 (1) ◽  
pp. 94-105 ◽  
Author(s):  
A Sikora ◽  
K Tomczuk
Keyword(s):  
Polymethyl Methacrylate ◽  
Pulse Width Modulation ◽  
Morphological Changes ◽  
Detection Sensitivity ◽  
Force Microscopy ◽  
Dc Power ◽  
Atomic Force ◽  
High Roughness ◽  
The Impact ◽  
Non Destructive

The popularity of LED-based luminaires has increased enormously in recent years. Every such luminaire consists of several elements including a polymer-based transparent housing, yet some of the ageing aspects of specific luminaire materials have not been investigated. In this paper, we present research aimed at determining the impact of LED lamp powering mode on polymer material deterioration. In the experiment, three LED lamp operating systems based on two different pulse width modulation units and one DC power source were used to induce deterioration in a polymethyl methacrylate sample. Two types of LEDs, white and ultraviolet, were considered as the most significant in terms of the impact on the material. Observations of the surface's morphological changes were performed to enable non-destructive investigation of the degradation of the exposed samples. In order to obtain high roughness detection sensitivity, atomic force microscopy was used. We observed various ageing ratios of the material, despite the fact that total average optical energy for specific wavelengths was equal for all samples. The importance of these findings for designing modern luminaires is discussed.

scholarly journals Compositional variation of AlGaN epitaxial films on 6H-SiC substrates determined by cathodoluminescence.

2002 ◽  
Vol 7 ◽  
Author(s):  
A. Petersson ◽  
Anders Gustafsson ◽  
L. Samuelson ◽  
Satoru Tanaka ◽  
Yoshinobu Aoyagi
Keyword(s):  
Epitaxial Film ◽  
Epitaxial Films ◽  
Compositional Variation ◽  
Initial Growth ◽  
Energy Position ◽  
Force Microscopy ◽  
Spatially Resolved ◽  
Atomic Force ◽  
Peak Energy ◽  
Micrometer Scale

High quality epitaxial films of AlxGa1−xN, grown on SiC substrates, were investigated using spatially resolved cathodoluminescence (CL), scanning electron microscopy, and atomic force microscopy. A variation in the observed peak energy position of the CL was related to alloy fluctuations. CL was used to reveal relative alloy fluctuations of approximately 1% on a sub-micrometer scale, with a precision difficult to surpass with other available techniques. By correlating data from the different techniques, a model was derived. The main feature of it is an alloy fluctuation on the micrometer scale, seeded during the initial growth and extending through the epitaxial film. These alloy fluctuations seems to be related to terrace steps (≈5 nm in height), formed preferentially at scratches on the SiC surface. This investigation indicates that the initial growth of epitaxial films is critical and structures formed at the beginning of the growth tend to persist throughout the growth. Further, a strain gradient from the SiC interface extending towards the surface, was observed.

Structural and Surface Morphology Changes in CuInSe2 Thin Films as a Function of Cu/In Ratio

1996 ◽  
Vol 441 ◽  
Author(s):  
P. Fons ◽  
S. Niki ◽  
A. Yamada ◽  
D. J. Tweet
Keyword(s):  
Thin Films ◽  
Molecular Beam ◽  
Morphological Changes ◽  
Epitaxial Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
The Ideal

AbstractDue to its high near bandedge absorption, CuInSe2 is considered to be one of the most promising solar cell materials. As CuInSe2 films are usually grown by metastable processes, the Cu/In ratio often deviates from the ideal ratio of unity. To investigate the structural and morphological changes induced by such stoichiometric variations we have grown a series of epitaxial CuInSe2 epitaxial thin films with varying Cu/In ratios by molecular beam epitaxy on GaAs(001) substrates from elemental sources at a growth temperature of 450° C. Overall structural, microstructural and surface morphological changes were observed by X-ray diffraction, transmission electron microscopy, and atomic force microscopy, respectively. It was observed that as films deviated from stoichiometry, twinning occurred preferentially on the anion {1 · 1 · 2} planes.

scholarly journals Deswelling Induced Morphological Changes in Dual pH and Temperature Responsive Ultra-Low Crosslinked Poly (N-Isopropyl Acrylamide)-Co-Acrylic Acid Microgels

2018 ◽  
Author(s):  
Molla Islam ◽  
Maddie Tumbarello ◽  
Andrew Lyon
Keyword(s):  
Light Scattering ◽  
Acrylic Acid ◽  
Morphological Changes ◽  
Scattering Data ◽  
Ionization State ◽  
Force Microscopy ◽  
Temperature Responsive ◽  
Atomic Force ◽  
Isopropyl Acrylamide ◽  
The Impact

<div>We demonstrated the deswelling induced morphological change in dual pH and Temperature responsive ultra-low crosslinked Poly (N-isopropyl acrylamide)-co-acrylic acid microgels. The responsivity with pH and temperature were studied by light scattering and atomic force microscopy. Light scattering data suggest that at pH 4.5 the microgels undergo multiple transitions associated with collapse of pNIPAm-rich segments and repulsion between the AAc-rich segments. The evolution of punctate structures around the periphery or throughout the whole microgels at pH 4.5 and 6.5 respectively was revealed by AFM, further illustrating the heterogeneous deswelling present in the ionized copolymer microgels.</div><div>The impact of this study and understanding how ionization state of copolymer dictates the overall structural properties of microgels will widen our understanding for their applications in biotechnology</div><div><b><br></b></div>

scholarly journals Исследование морфологии поверхности, электрофизических характеристик и спектров фотолюминесценции эпитаксиальных плёнок GaAs на подложках GaAs (110)

2020 ◽  
Vol 129 (7) ◽  
pp. 877
Author(s):  
Г.Б. Галиев ◽  
Е.А. Климов ◽  
А.А. Зайцев ◽  
С.С. Пушкарев ◽  
А.Н. Клочков
Keyword(s):  
Atomic Force Microscopy ◽  
Point Defects ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Epitaxial Films ◽  
Photoluminescence Spectra ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wide Range ◽  
Silicon Doped

The electrophysical and photoluminescent characteristics as well as the surface morphology of GaAs epitaxial films grown by molecular beam epitaxy on GaAs (110) substrates are studied. Silicon-doped epitaxial layers were grown in a wide range of growth temperatures from 410 to 680 °C and a ratio of arsenic and gallium fluxes from 14 to 84. The ranges of growth conditions resulting in the smoothest epitaxial films surface were estimated by atomic force microscopy. The occurrence of point defects "a Si atom in a Ga site" and "a Si atom in a As site" as well as the formation of arsenic and gallium vacancies were interpreted by analyzing the photoluminescence spectra of the grown samples.

GaAs-on-Ge Heteroepitaxy by Atomic Hydrogen-Assisted Molecular Beam Epitaxy (H-MBE)

1995 ◽  
Vol 399 ◽  
Author(s):  
Yoshitaka Okada ◽  
James S. Harris ◽  
Atsushi Sutoh ◽  
Mitsuo Kawabe
Keyword(s):  
Molecular Beam Epitaxy ◽  
Atomic Hydrogen ◽  
Molecular Beam ◽  
High Energy ◽  
Atomic Scale ◽  
Layer By Layer ◽  
High Quality ◽  
Force Microscopy ◽  
Atomic Force ◽  
Growth System

ABSTRACTThe purpose of this work is to achieve a high-quality epitaxy of GaAs-on-Ge system at low growth temperatures of 300 ∼ 400°C, by atomic hydrogen-assisted molecular beam epitaxy (H-MBE), in attempt to reduce Ge segregation to a minimum and to realize a layer-by-layer two-dimensional (2D) growth mode from the initial stages of the growth. A high-quality heteroepitaxy is expected in H-MBE technique as atomic H is known to act as an effective surfactant modifying the kinetics and energetics of the growth, which are practically difficult to control on atomic-scale unless a third element like a surfactant is introduced into the growth system. It is shown with the support of reflection high-energy electron diffraction (RHEED), secondary ion mass spectroscopy (SIMS), and atomic force microscopy (AFM) characterization that an enhanced layer-by-layer 2D growth can actually be realized and (2×4) GaAs(001) surface can be achieved in low-temperature heteroepitaxy on vicinal Ge(001) substrates at 400 °C by H-MBE.

Nanopatterning of GaAs(110) vicinal surfaces by hydrogen-assisted MBE

2004 ◽  
Vol 849 ◽  
Author(s):  
M. L. Crespillo ◽  
J. L. Sacedón ◽  
B. A. Joyce ◽  
P. Tejedor
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Beam ◽  
Self Organization ◽  
Atomic Step ◽  
Vicinal Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Ridge Pattern ◽  
Oxide Removal ◽  
Mound Morphology

ABSTRACTThe effect of atomic hydrogen on the growth mode and surface morphology of GaAs(110) thin films grown by molecular beam epitaxy (H-MBE) has been studied for different kinetic regimes using atomic force microscopy (AFM). Growth in the Ga supply-limited regime after H-assisted oxide removal leads to the formation of multi-atomic step arrays by step bunching with a very uniform terrace size distribution in the 80 nm range. Growth under As-deficient conditions after H-assisted oxide removal induces a rapid self-organization of the GaAs(110) surface into a ridge pattern along the <001> tilt direction, which is broken down into a 3D mound morphology when H is also present during growth. A chacteristic nanofacetting of the surface with very straight <1–10> -type steps is observed at high temperatures regardless of atomic hydrogen being used during oxide desorption and/or epitaxial growth.

Structural and Optical Properties of InAsSbBi Grown by Molecular Beam Epitaxy on Offcut GaSb Substrates

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 215
Author(s):  
Rajeev R. Kosireddy ◽  
Stephen T. Schaefer ◽  
Marko S. Milosavljevic ◽  
Shane R. Johnson
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Optical Quality ◽  
X Ray Diffraction ◽  
Interface Quality ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Lateral Variations

Three InAsSbBi samples are grown by molecular beam epitaxy at 400 °C on GaSb substrates with three different offcuts: (100) on-axis, (100) offcut 1° toward [011], and (100) offcut 4° toward [011]. The samples are investigated using X-ray diffraction, Nomarski optical microscopy, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The InAsSbBi layers are 210 nm thick, coherently strained, and show no observable defects. The substrate offcut is not observed to influence the structural and interface quality of the samples. Each sample exhibits small lateral variations in the Bi mole fraction, with the largest variation observed in the on-axis growth. Bismuth rich surface droplet features are observed on all samples. The surface droplets are isotropic on the on-axis sample and elongated along the [011¯] step edges on the 1° and 4° offcut samples. No significant change in optical quality with offcut angle is observed.

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