The Effect of Growth Temperature on Atomic Ordering in Gao.5 2Ino.48P Epilayers Grown on GaAs (001) Substrates by GS-MBE

AbstractA Transmission Electron Microscopy (TEM), Photoluminescence (PL) and Photoluminescence Excitation Spectroscopy (PLE) investigation has been conducted on Ga0 52In0.48P epilayers, grown on GaAs(001) by Gas-Source Molecular Beam Epitaxy. Selected area diffraction in the TEM shows that epilayers grown at temperatures between 480°C and 535°C exhibit CuPt-type ordering with the antiphase domain size increasing with increasing growth temperature. PLE data shows that, in the temperature range 480°C to 535°C the band gap energy of Ga0.52In0-48P epilayers increases with increasing growth temperature from 1.971 to 2.003 (±0.001 eV). For high band gap optical data storage applications these values compare well with the highest band gap energies reported for epilayers grown by MOCVD.

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Influence of Growth Temperature and Phosphine Flow on CuPt Type Ordering in InGaP Grown by Chemical Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-618-259 ◽

2000 ◽

Vol 618 ◽

Author(s):

J. Bettini ◽

M.M.G. de Carvalho ◽

M. A. Hayashi ◽

L. P. Cardoso ◽

D. Ugarte

Keyword(s):

Band Gap ◽

Growth Temperature ◽

Diffuse Scattering ◽

Band Gap Energy ◽

Dark Field ◽

Chemical Beam Epitaxy ◽

Small Reduction ◽

Gap Energy ◽

Transmission Electron ◽

Long Range Ordering

ABSTRACTIn this work, In0.5Ga0.5P layers were grown by Chemical Beam Epitaxy on GaAs (001) substrates. A set of samples was grown with temperatures kept in the range of 500°C to 560°C with V/III ratio 15. Another set was grown at 560°C with V/II ratio varied in the range 15 to 35. The evolution of ordering as function of growth temperature and V/III ratio was evaluated by photoluminescence measurements at 77K, Transmission Electron Diffraction (TED) and images using Transmission Electron Microscopy (TEM)-Dark Field. A 48meV reduction in the band gap energy was measured by photoluminescence measurements at 77 K when growth temperature was increased. This result is associated to the occurrence of CuPtB ordering in the InGaP layers observed by TED. The TEM-Dark field examination shows that the ordered domains are larger for samples grown at higher temperaturesA small reduction in band gap, from 1.915eV to 1.902eV, occurs when the V/III ratio is increased from 15 to 35. The TED patterns present diffuse scattering for all samples. For those grown with higher V/III ratio, spots are also observed. TEM-dark field images show that the ordered regions become larger, elongated and inclined; some of them exhibit long range ordering

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TEM Specimen Preparation Techniques and Analysis of Photo-Thermo-Refractive Glasses (PTRG)

Microscopy and Microanalysis ◽

10.1017/s1431927600028233 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 432-433

Author(s):

H. Francois-Saint-Cyr ◽

K. Elshot ◽

P. Le Coustumer ◽

X. Bourrat ◽

K. Richardson ◽

...

Keyword(s):

Data Storage ◽

Refractive Index Change ◽

Optical Data Storage ◽

Optical Data ◽

Specimen Preparation ◽

Active Components ◽

Index Change ◽

Transmission Electron ◽

Optical Applications ◽

Underlying Mechanisms

Due to their ability to undergo a refractive index change (Δn) induced by appropriate UV irradiation and thermal development, Photo-Thermo-Refractive (PTR) glasses are candidate materials for use in optical applications such as hologram recording, optical data storage, or spectral filters. Although this induced index modulation (Δn) has been characterized in terms of its optical ramifications, glass scientists are working to understand more clearly, the underlying mechanisms associated with the photo-induced crystallization process. For example, the phase, concentration and size of crystals responsible for the induced index change, the diffusion and growth process leading to the resultant optical behavior, and the precise role of the active components of PTR glasses, has yet to be completely elucidated. Numerous techniques have been employed to address these questions and this paper reports results of sample preparation and analysis of PTR glasses using Transmission Electron Microscopy (TEM).

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Structural and optical properties of amorphous Si–Ge–Te thin films prepared by combinatorial sputtering

Scientific Reports ◽

10.1038/s41598-021-91138-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

C. Mihai ◽

F. Sava ◽

I. D. Simandan ◽

A. C. Galca ◽

I. Burducea ◽

...

Keyword(s):

Optical Properties ◽

Data Storage ◽

Optical Sensors ◽

Material Selection ◽

Functional Materials ◽

Stability Study ◽

Optical Data Storage ◽

Optical Data ◽

Structural And Optical Properties ◽

Topological Constraint

AbstractThe lack of order in amorphous chalcogenides offers them novel properties but also adds increased challenges in the discovery and design of advanced functional materials. The amorphous compositions in the Si–Ge–Te system are of interest for many applications such as optical data storage, optical sensors and Ovonic threshold switches. But an extended exploration of this system is still missing. In this study, magnetron co-sputtering is used for the combinatorial synthesis of thin film libraries, outside the glass formation domain. Compositional, structural and optical properties are investigated and discussed in the framework of topological constraint theory. The materials in the library are classified as stressed-rigid amorphous networks. The bandgap is heavily influenced by the Te content while the near-IR refractive index dependence on Ge concentration shows a minimum, which could be exploited in applications. A transition from a disordered to a more ordered amorphous network at 60 at% Te, is observed. The thermal stability study shows that the formed crystalline phases are dictated by the concentration of Ge and Te. New amorphous compositions in the Si–Ge–Te system were found and their properties explored, thus enabling an informed and rapid material selection and design for applications.

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Optical Isomerization and Photo-Patternable Properties of GeO2/Ormosils Organic-Inorganic Composite Films Doped with Azobenzene

Coatings ◽

10.3390/coatings11070818 ◽

2021 ◽

Vol 11 (7) ◽

pp. 818

Author(s):

Xuehua Zhang ◽

Qian Wang ◽

Shun Liu ◽

Wei Zhang ◽

Fangren Hu ◽

...

Keyword(s):

Optical Waveguide ◽

Data Storage ◽

Optical Switching ◽

Sol Gel ◽

Composite Films ◽

Optical Data Storage ◽

Optical Data ◽

Single Chip ◽

Coating Method ◽

Inorganic Composite

GeO2/organically modified silane (ormosils) organic-inorganic composite films containing azobenzene were prepared by combining sol-gel technology and spin coating method. Optical waveguide properties including the refractive index and thickness of the composite films were characterized by using a prism coupling instrument. Surface morphology and photochemical properties of the composite films were investigated by atomic force microscope and Fourier transform infrared spectrometer. Results indicate that the composite films have smooth and neat surface, and excellent optical waveguide performance. Photo-isomerization properties of the composite films were studied by using a UV–Vis spectrophotometer. Optical switching performance of the composite films was also studied under the alternating exposure of 365 nm ultraviolet light and 410 nm visible light. Finally, strip waveguides and microlens arrays were built in the composite films through a UV soft imprint technique. Based on the above results, we believe that the prepared composite films are promising candidates for micro-nano optics and photonic applications, which would allow directly integrating the optical data storage and optical switching devices onto a single chip.

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