Відображення розвитку науки України та Євросоюзу в реферативній базі даних SCOPUS

Досліджено публікаційну активність України та Євросоюзу за галузями науки. Розглянуто динаміку кількості публікацій, що припадають на одного дослідника впродовж 1996-2010 рр. Виконано порівняння відображення кількості публікацій БД Scopus у ВВП та витратах на НДДКР країн в розрахунку на кожен 1 млн. дол. США.Исследована публикационная активность Украины и Евросоюза по отраслям науки. Рассмотрена динамика количества публикаций, которые приходятся на одного исследователя на протяжении 1996–2010 гг. Сделано сравнение отображения количества публикаций БД Scopus в ВВП и затратах на НДДКР стран в расчете на каждый 1 млн. дол. США.The publication activity by fields of science of Ukraine and the European Union was investigated. The dynamics of the number of publications per 1 researcher was considered during 1996–2010 years. Countries comparison by the number of publications reflecting in GDP and R&D expenditures per 1 million U.S. dollars measurements in the abstract database Scopus was done

Anisotropy in the surface chemistry of silicon in alkaline solution

This thesis describes a study of the anisotropy in the surface chemistry of silicon in aqueous KOH solutions. Two main reactions are considered: chemical etching, and electrochemical oxidation and passivation. Anisotropic etching of masked (100) surfaces was used to form V-grooves exposing well-defined (111) facets. With this geometry it was possible to study both the chemical and electrochemical reactions at the (100) and (111) surfaces of the same material, simultaneously (chapter 2). The most striking result is perhaps the very strong anisotropy observed in electrochemical oxidation. The general features of these results could be accounted for by a previously proposed two-step mechanism, in which Si - H surface bonds are converted to Si - OH by an OH- catalyzed reaction and the polarized Si - Si back-bonds are subsequently attacked by water. Anodic current is due to injection of electrons into the conduction band from activated intermediates of the two chemical reactions. This concerted chemical-electrochemical mechanism accounts for the remarkably slow kinetics of anodic oxidation of n-type (111) surfaces. In chapter 3 it is shown that FTIR spectroscopy can be used very effectively to follow in situ the surface chemistry of silicon during anisotropic etching, anodic oxidation and passivation, and etch-back of the passivating oxide. While the first of the two chemical steps described above is generally considered to be rate determining for the chemical and electrochemical processes, the IR measurements show that oxide formation on ideally flat n-type (111) surfaces at room temperature is slow even though there is a considerable Si - OH coverage of the surface. The combination of potential-step and FTIR measurements is particularly effective for such studies. Anodic current transients measured after a potential step on well-defined n-type (111) electrodes can be used to obtain information about the chemical reactivity of the surface. In chapter 4 the effect of additives (hydrogen peroxide and isopropyl alcohol) on the kinetics of surface reactions is described. An electrochemical flow cell in combination with an optical microscope was designed to study in situ changes in morphology of silicon during chemical etching and electrochemical oxidation (chapter 5). The power of this approach was demonstrated by a study in real time of the evolution of the typical roof-tile morphology on Si(110) surfaces. A simple image-processing procedure was developed to quantify the changes in morphological structures. This approach, in combination with ex situ microscopic observation, gives a wealth of information about the relation between etch morphology and parameters such as KOH concentration, applied electrochemical potential and the presence of additives (H2O2). Chapter 6 shows how the V-groove geometry can be employed to measure in situ chemical etch rates, using either electrochemical measurements or in situ optical microscopy. These approaches applied to a test wafer could be used for process control in the batch fabrication of devices. Another very interesting extension of the electrochemical approach is the possibility of following in situ the change in geometry of anisotropically etched deep trenches and buried structures in wafers

Influence of chemical additives on the surface reactivity of Si in KOH solution

It is known that the electrochemistry of silicon in alkaline solution is closely linked to the anisotropic etching of the semiconductor. In this work the influence of two commonly used additives, hydrogen peroxide and isopropyl alcohol, on the surface chemistry of silicon in KOH solution was investigated by electrochemical methods. The results allow us to draw conclusions regarding the role of the additives in the chemical and electrochemical reactions

Influence of chemical additives on the surface reactivity of Si in KOH solution

It is known that the electrochemistry of silicon in alkaline solution is closely linked to the anisotropic etching of the semiconductor. In this work the influence of two commonly used additives, hydrogen peroxide and isopropyl alcohol, on the surface chemistry of silicon in KOH solution was investigated by electrochemical methods. The results allow us to draw conclusions regarding the role of the additives in the chemical and electrochemical reactions

In-situ IR spectroscopy to study anodic oxidation of Si(111) in KOH solution

Fourier Transform Infrared (FTIR) spectroscopy was used to study in-situ the anodic oxidation of n-type Si(111) in KOH solution. Changes in surface chemistry were followed during oxide growth. The results are considered on the basis of a model developed from electrochemical measurements

Oxide Formation and Dissolution on Silicon in KOH Electrolyte: An In-Situ infrared Study

The n-Si(111)/6 M KOH electrolyte interface has been investigated by in-situ multiple-internal reflection infrared spectroscopy, at room temperature and at 40°C. The potential was stepped successively to positive and negative values with respect to open-circuit potential, during which surface oxidation and oxide dissolution occur, respectively. Infrared spectra were recorded together with the interfacial current. Analysis of the spectra indicates that formation of an oxide layer at the positive potential takes place in two steps: a first step associated with replacement of the surface SiH by SiOH or SiO− groups, and a second step, associated with the formation of SiOSi groups and growth of a passivating oxide layer. The mechanism is strongly dependent on the competition between oxidation and dissolution, which accounts for the complex shape of the current transient and its temperature dependence. At the negative potential, dissolution of the oxide takes place by random pitting, until the hydrogenated surface is restored

Oxide Formation and Dissolution on Silicon in KOH Electrolyte: An In-Situ infrared Study

The n-Si(111)/6 M KOH electrolyte interface has been investigated by in-situ multiple-internal reflection infrared spectroscopy, at room temperature and at 40°C. The potential was stepped successively to positive and negative values with respect to open-circuit potential, during which surface oxidation and oxide dissolution occur, respectively. Infrared spectra were recorded together with the interfacial current. Analysis of the spectra indicates that formation of an oxide layer at the positive potential takes place in two steps: a first step associated with replacement of the surface SiH by SiOH or SiO− groups, and a second step, associated with the formation of SiOSi groups and growth of a passivating oxide layer. The mechanism is strongly dependent on the competition between oxidation and dissolution, which accounts for the complex shape of the current transient and its temperature dependence. At the negative potential, dissolution of the oxide takes place by random pitting, until the hydrogenated surface is restored