Mechanisms of the Phase Separation of Nonstoichiometric Si Oxide Films: What Can One Learn From Thermodynamics?

This paper describes thermodynamic approach to the study of the mechanisms of phase separation in nonstoichiometric silicon oxide (SiOx, x < 2) films during high temperature annealing, which produces the nanometer sized Si inclusions embedded in the Si oxide matrix. The expression for the Gibbs free energy of Si/Si oxide systems is derived based on the analysis of the processes taking place during the phase separation. The progress of phase separation is characterized by the evolution of the stoichiometry index of Si oxide matrix x. The mechanisms assisting and counteracting the phase separation of SiOx films are determined based on that whether their contributions to the Gibbs free energy decrease or increase with the progress of Si and Si oxide separation (increase of x). The mechanisms responsible for the formation of equilibrium states in the Si/Si oxide systems (equilibrium values of x) are determined

Mechanisms of the Phase Separation of Nonstoichiometric Si Oxide Films: What Can One Learn From Thermodynamics?

This paper describes thermodynamic approach to the study of the mechanisms of phase separation in nonstoichiometric silicon oxide (SiOx, x < 2) films during high temperature annealing, which produces the nanometer sized Si inclusions embedded in the Si oxide matrix. The expression for the Gibbs free energy of Si/Si oxide systems is derived based on the analysis of the processes taking place during the phase separation. The progress of phase separation is characterized by the evolution of the stoichiometry index of Si oxide matrix x. The mechanisms assisting and counteracting the phase separation of SiOx films are determined based on that whether their contributions to the Gibbs free energy decrease or increase with the progress of Si and Si oxide separation (increase of x). The mechanisms responsible for the formation of equilibrium states in the Si/Si oxide systems (equilibrium values of x) are determined

Characteristics of gettering process in multicrystalline Si wafers with combined porous Si/Al getters

In this work, the gettering process in the multicrystalline Si wafers by the combined getter structures of the porous Si and Al layers during annealings at temperatures 600 up to 750 °C has been theoretically studied. A kinetic model based on the diffusion equation has been developed, and the characteristics of increase in the minority charge carrier diffusion length as a result of gettering annealings have been determined. The obtained results are useful for technology of multicrystalline Si solar cells to improve their properties

Изучение процессов формирования массивов капель золота на подложках кремния методом высокотемпературного отжига

In this study, the peculiarities of the transformations of gold films deposited on the Si wafer surfaces as a result of high temperature anneals are investigated experimentally depending on the conditions of wafer surface preparation and the annealing regimes. The morphology and the distribution functions of the crystallites of gold films as well as the gold droplets formed as a result of anneals are studied as functions of annealing temperature, type of annealing (rapid thermal or rapid furnace annealing), and the state of the surface of Si wafers. The results obtained can be used for the controlled preparation of the arrays of catalytic gold droplets for subsequent growth of Si wire-like crystals.В роботі вивчено особливості трансформації золотих плівок, нанесених на поверхню кремнієвих пластин, в результаті високотемпературного відпалу в залежності від умов підготовки поверхні пластин та режимів відпалу. Морфологія і розподіл кристалітів плівок золота, а також масивів крапель золота, сформованих в результаті відпалу, досліджені як функції температури і типу відпалу (швидкий термічний або швидкий відпал в печі) та стану поверхні пластин Si. Отримані результати можуть бути використані для контролю виготовлення масивів каталітичних крапель золота для подальшого вирощування нитковидних кристалів Si.В работе изучены особенности трансформации золотых пленок, нанесенных на поверхность кремниевых пластин, в результате высокотемпературного отжига в зависимости от условий подготовки поверхности пластин и режимов отжига. Морфология и распределение кристаллитов пленок золота, а также массивов капель золота, сформированных в результате отжига, исследованы как функции температуры и типа отжига (быстрый термический или быстрый отжиг в печи) и состояния поверхности пластин Si. Полученные результаты могут быть использованы для контроля изготовления массивов каталитических капель золота для последующего выращивания нитевидных кристаллов Si

Thermodynamic driving force in the formation of hexagonal-diamond Si and Ge nanowires

The metastable hexagonal-diamond phase of Si and Ge (and of SiGe alloys) displays superior optical properties with respect to the cubic-diamond one. Based on first-principle calculations we show that the surface energy of the typical facets exposed in Si and Ge nanowires is lower in the hexagonal-diamond phase than in the cubic one. By exploiting a synergic approach based also on a recent state-of-the-art interatomic potential and on a simple geometrical model, we investigate the relative stability of nanowires in the two phases up to few tens of nm in radius, highlighting the surface-related driving force and discussing its relevance in recent experiments. We also explore the stability of Si and Ge core-shell nanowires with hexagonal cores (made of GaP for Si nanowires, of GaAs for Ge nanowires). In this case, the stability of the hexagonal shell over the cubic one is also favored by the energy cost associated with the interface linking the two phases. Interestingly, our calculations indicate a critical radius of the hexagonal shell much lower than the one reported in recent experiments, indicating the presence of a large kinetic barrier allowing for the enlargement of the wire in a metastable phase

Unveiling Planar Defects in Hexagonal Group IV Materials

Recently synthesized hexagonal group IV materials are a promising platform to realize efficient light emission that is closely integrated with electronics. A high crystal quality is essential to assess the intrinsic electronic and optical properties of these materials unaffected by structural defects. Here, we identify a previously unknown partial planar defect in materials with a type I 3 basal stacking fault and investigate its structural and electronic properties. Electron microscopy and atomistic modeling are used to reconstruct and visualize this stacking fault and its terminating dislocations in the crystal. From band structure calculations coupled to photoluminescence measurements, we conclude that the I 3 defect does not create states within the hex-Ge and hex-Si band gap. Therefore, the defect is not detrimental to the optoelectronic properties of the hex-SiGe materials family. Finally, highlighting the properties of this defect can be of great interest to the community of hex-III-Ns, where this defect is also present

Author Correction:In-plane selective area InSb–Al nanowire quantum networks (Communications Physics, (2020), 3, 1, (59), 10.1038/s42005-020-0324-4)

The Data availability statement of this article has been modified to add the accession link to the raw data. The old Data availability statement read “Materials and data that support the findings of this research are available within the paper. All data are available from the corresponding author upon request”. This has been replaced by “Materials and data that support the findings of this research are available within the paper. The raw data have been deposited at https://zenodo.org/record/4589484#.YEoEOy1Y7Sd”. This has been corrected in both the HTML and PDF version of the article.</p