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1

Evolution of InAs Quantum Dots during Annealing Process

100%

Guo-zhi J., Jiang-hong Y., Yong-chun S., Xiao-dong X., Pi-Biao

Acta Physica Polonica A

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2008

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vol. 114

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issue 4

919-923

EN

InAs quantum dots were grown by molecular beam epitaxy in the Stranski-Krastanow growth mode and annealed under N_2 atmospheres at different temperatures. The evolution of quantum dots with the annealing temperature increasing were slightly different with the results reported in the literature. Atomic force microscopy investigations of quantum dots uncapped layer show a size initial increase followed by a prompt decrease as annealing temperature increases. It was found that the photoluminescence signal on quantum dots capped with GaAs layer was first slightly red-shifted and then blue-shifted with an increase in annealing temperature. The blue-shift can be attributed to In/Ga interdiffusion in annealing process. Red-shift of optical features indicates the change of the quantum dots compostion, size, and strain from the barrier.

2

CdSe/ZnSe Quantum Dots Formed by Low Temperature Epitaxy and In-Situ Annealing: Properties and Growth Optimization

100%

Mahapatra S., Schumacher C., Kiessling T., Astakhov G., Bass U., Ossau W., Geurts J., Brunner K.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

769-776

EN

The formation of CdSe/ZnSe quantum dots by a method combining a low temperature MBE growth of a CdSe layer and its subsequent in-situ annealing at temperatures between 280-340ºC has been studied. The thermal treatment results in a re-organization of the surface from a nearly two-dimensional layer to an ensemble of three-dimensional dot-like features. In this work we optimized the different growth and annealing parameters of this process and compared the properties of the resultant dots with those of dots grown by conventional MBE at 300ºC. It is demonstrated that the luminescence properties of the dots for both growth techniques are comparable but the areal density achieved by the in-situ annealing technique is an order of magnitude lower. From high resolution X-ray diffraction results, it could be established that no desorption takes place despite significantly long annealing duration. Beyond a nominal coverage of 3.5 ML CdSe, stacking faults are generated, leading to a gradual decrease in luminescence intensities and an overlap of pendellösung fringes in X-ray diffractograms.

3

Comparison of the Fe and Pt Nanoparticles with FePt Alloy Prepared by Polyol Process: Shape and Composition Study

100%

Farahmandjou M.

Acta Physica Polonica A

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2013

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vol. 123

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issue 2

277-278

EN

In this study, Fe and Pt nanoparticles are first synthesized by decomposition of iron(II) chloride tetrahydrate and reduction of platinum(II) acetylacetonate. Then, FePt nanoparticles are similarly fabricated by adding LiBEt3H to the phenyl ether solution in the presence of oleic acid, oleylamine surfactant at 100°C, followed by refluxing at 255°C. The samples were characterized by transmission electron microscopy and energy dispersive spectroscopy analyses after heat treatments. Transmission electron microscopy images show that self-assembled 8 nm Fe nanoparticles are formed as polygon shape, whereas Pt nanoparticles have broad size distribution. On the other hand, 4.5 nm FePt nanoparticles have standard division about 9%. The results of energy dispersive spectroscopy analysis reveal that the composition of Pt, Fe and FePt nanoparticles gives Fe_{56}Pt_{44} stoichiometry.

4

InSb Quantum Dots in an InAsSb Matrix Grown by Molecular Beam Epitaxy

88%

Semenov A., Solov'ev V., Meltser B., Lyublinskaya O., Terent'ev Y., Sitnikova A., Ivanov S.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

859-865

EN

We report on molecular beam epitaxy of InSb insertions in InAs and InAsSb matrices, emitting at wavelengths beyond 4μm. Different growth techniques for deposition of InSb quantum dots in the 1-2 monolayer range of the InSb nominal thickness, namely conventional molecular beam epitaxy and migration enhanced epitaxy, as well as different matrices (InAs and InAsSb) have been employed for increasing the emission wavelength of the InSb/InAs nanostructures. The formation of InSb quantum dots has been studied in situ using reflection high energy electron diffraction and ex situ by using transmission electron microscopy. The peculiarities of In(Ga)AsSb alloys growth and compositional control are also discussed. Bright photoluminescence up to 4.5μm has been observed at 80 K.

5

Structures in Multicomponent Polymer Films: Their Formation, Observation and Applications in Electronics and Biotechnology

75%

Budkowski A., Bernasik A., Moons E., Lekka M., Zemła J., Jaczewska J., Haberko J., Raczkowska J., Rysz J., Awsiuk K.

Acta Physica Polonica A

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2009

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vol. 115

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issue 2

435-440

EN

Several strategies to form multicomponent films of functional polymers, with micron, submicron and nanometer structures, intended for plastic electronics and biotechnology are presented. These approaches are based on film deposition from polymer solution onto a rotating substrate (spin-casting), a method implemented already on manufacturing lines. Film structures are determined with compositional (nanometer) depth profiling and (submicron) imaging modes of dynamic secondary ion mass spectrometry, near-field scanning optical microscopy (with submicron resolution) and scanning probe microscopy (revealing nanometer features). Self-organization of spin-cast polymer mixtures is discussed in detail, since it offers a one-step process to deposit and align simultaneously domains, rich in different polymers, forming various device elements: (i) Surface segregation drives self-stratification of nanometer lamellae for solar cells and anisotropic conductors. (ii) Cohesion energy density controls morphological transition from lamellar (optimal for encapsulated transistors) to lateral structures (suggested for light emitting diodes with variable color). (iii) Selective adhesion to substrate microtemplates, patterned chemically, orders lateral structures for plastic circuitries. (iv) Submicron imprints of water droplets (breath figures) decorate selectively micron-sized domains, and can be used in devices with hierarchic structure. In addition, selective protein adsorption to regular polymer micropatterns, formed with soft lithography after spin-casting, suggests applications in protein chip technology. An approach to reduce lateral blend film structures to submicron scale is also presented, based on (annealed) films of multicomponent nanoparticles.

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Evolution of InAs Quantum Dots during Annealing Process

CdSe/ZnSe Quantum Dots Formed by Low Temperature Epitaxy and In-Situ Annealing: Properties and Growth Optimization

Comparison of the Fe and Pt Nanoparticles with FePt Alloy Prepared by Polyol Process: Shape and Composition Study

InSb Quantum Dots in an InAsSb Matrix Grown by Molecular Beam Epitaxy

Structures in Multicomponent Polymer Films: Their Formation, Observation and Applications in Electronics and Biotechnology