ОПТИМИЗАЦИЯ УРОВНЯ ЛЕГИРОВАНИЯ КРЕМНИЯ «СОЛНЕЧНОГО» КАЧЕСТВА ДЛЯ ПОВЫШЕНИЯ ПРИГОДНОГО ОБЪЕМА СЛИТКОВ И КПД СОЛНЕЧНЫХ ЭЛЕМЕНТОВ

In the close future, use of SoG should become prominent for photovoltaic ingot production as it requires much less energy for purification compared to Silicon grades using gas transformation and purification (usually Siemens process or equivalent also used for electronic−grade preparation). During this study, several kinds of silicon were compared with different rates of dopant content (mainly boron and phosphorus). Ingot yield and cell efficiency were optimized for each source of silicon at a production level (450 kg ingots) using boron or gallium doping. Starting from the resistivity specification given by the cell process, the doping level was adjusted in order to maximize the ingot silicon yield (weight of silicon bricks used for wafer cutting/ weight of Silicon ingot). After doping adjustment, ingot quality was checked: brick resistivity, lifetime of minority carriers and wafers were processed into solar cells. Optimizing of doping led to get comparable ingot yields and cell efficiencies using SoG and silicon purified by Siemens process or equivalent. The study was implemented at Kazakhstan Solar Silicon plant in Ust−Kamenogorsk using Kazakhstan SoG, SoG from a European manufacturer and polycrystalline Silicon purified by Siemens process. Directional solidification furnaces were manufactured by the French company ECM Technologies.В ближайшем будущем поликристаллический кремний (ПК) «солнечного» качества (SoG) станет основным материалом для выращивания слитков мультикристаллического кремния (МКК), предназначенных для фотовольтаического (ФВ) производства, так как требует гораздо меньше энергии для очистки по сравнению с ПК, полученным в Сименс−процессе (ПК электронного качества).Рассмотрено несколько видов ПК с различным уровнем содержания примесей (преимущественно бора и фосфора). Для каждого из этих видов ПК при выращивании их них слитков МКК в промышленном масштабе с использованием примесей бора и галлия оптимизированы выход годного кремния и эффективность солнечных элементов. Уровень легирования рассчитан таким образом, чтобы увеличить выход годного кремния из слитка МКК. После получения слитков проверено их качество (изменение удельного сопротивления по высоте кремниевых блоков, время жизни неосновных носителей заряда) и затем из пластин созданы солнечные элементы. За счет оптимизации уровня легирования выращены сопоставимые по выходу годного кремния слитки МКК из ПК SoG и ПК, полученного Сименс− процессом, а также изготовлены солнечные элементы, сопостовимые по эффективности преобразования солнечной энергии (КПД).Исследование проведено на заводе Kazakhstan Solar Silicon в Усть−Каменогорске, с применением казахстанского и европейского ПК SoG, а также ПК, полученного Сименс− процессом. Печи для направленной кристаллизации для выращивания МКК изготовлены французской компанией ECM Technologies

Combined analgesics in (headache) pain therapy: shotgun approach or precise multi-target therapeutics?

<p>Abstract</p> <p>Background</p> <p>Pain in general and headache in particular are characterized by a change in activity in brain areas involved in pain processing. The therapeutic challenge is to identify drugs with molecular targets that restore the healthy state, resulting in meaningful pain relief or even freedom from pain. Different aspects of pain perception, i.e. sensory and affective components, also explain why there is not just one single target structure for therapeutic approaches to pain. A network of brain areas ("pain matrix") are involved in pain perception and pain control. This diversification of the pain system explains why a wide range of molecularly different substances can be used in the treatment of different pain states and why in recent years more and more studies have described a superior efficacy of a precise multi-target combination therapy compared to therapy with monotherapeutics.</p> <p>Discussion</p> <p>In this article, we discuss the available literature on the effects of several fixed-dose combinations in the treatment of headaches and discuss the evidence in support of the role of combination therapy in the pharmacotherapy of pain, particularly of headaches. The scientific rationale behind multi-target combinations is the therapeutic benefit that could not be achieved by the individual constituents and that the single substances of the combinations act together additively or even multiplicatively and cooperate to achieve a completeness of the desired therapeutic effect.</p> <p>As an example the fixesd-dose combination of acetylsalicylic acid (ASA), paracetamol (acetaminophen) and caffeine is reviewed in detail. The major advantage of using such a fixed combination is that the active ingredients act on different but distinct molecular targets and thus are able to act on more signalling cascades involved in pain than most single analgesics without adding more side effects to the therapy.</p> <p>Summary</p> <p>Multitarget therapeutics like combined analgesics broaden the array of therapeutic options, enable the completeness of the therapeutic effect, and allow doctors (and, in self-medication with OTC medications, the patients themselves) to customize treatment to the patient's specific needs. There is substantial clinical evidence that such a multi-component therapy is more effective than mono-component therapies.</p

Wet and Siconi® cleaning sequences for SiGe p-type metal oxide semiconductor channels

International audienceThe low temperature integration of new materials (such as SiGe channels for the holes) is mandatory in advanced metal oxide semiconductor field effect transistors (i.e. in 14 nm technology node devices and beyond). In this paper, we have investigated the removal of SiGe oxides prior to Selective epitaxial Growth of Si or SiGe:B in Sources/Drains regions. A very efficient removal of contaminants (C, F, O…) is mandatory if the H2 bake that precedes epitaxy is removed because of thermal budget constraints. As germanium is very reactive in the air, in-situ surface preparation schemes (conducted for instance in a Siconi® chamber) might be useful on SiGe surfaces. This way, the queue-time issues associated with “HF-Last” (HF/HCl follow by deionization water rinse) processes in single wafer wet cleaning tools are avoided. Germanium-rich SiGe layers (Si0.6Ge0.4) were used to characterize the native oxide removal efficiency of “HF-Last” and Siconi® processes. Then, a new surface preparation strategy was developed based on i) a wet chemical oxide formation followed by ii) a standard Siconi® process whose efficiency towards SiO2 has conclusively been demonstrated. Parallel Angle Resolved X-ray Photoelectron Spectroscopy was used to study the chemical composition of the native or chemical oxide and evaluate the efficiency of that treatment on carbon, germanium oxide and silicon oxide

Ab initio theoretical comparative study of magnetic coupling in KNiF3 and K2NiF4s

The origin of magnetic coupling in KNiF3 and K2 NiF4 is studied by means of an ab initio cluster model approach. By a detailed study of the mapping between eigenstates of the exact nonrelativistic and spin model Hamiltonians it is possible to obtain the magnetic coupling constant J and to compare ab initio cluster-model values with those resulting from ab initio periodic Hartree-Fock calculations. This comparison shows that J is strongly determined by two-body interactions; this is a surprising and unexpected result. The importance of the ligands surrounding the basic metal-ligand-metal interacting unit is reexamined by using two different partitions and the constrained space orbital variation method of analysis. This decomposition enables us to show that this effect is basically environmental. Finally, dynamical electronic correlation effects have found to be critical in determining the final value of the magnetic coupling constant