Influence of initial defects on defect formation process in ion doped silicon

We study the influence of initial defects in high-resistance epitaxial silicon layers of high-resistance epitaxial silicon structures on defect formation processes at ion boron doping. The method of reverse voltage-capacitance characteristics revealed two maxima of dopant concentration in epitaxial silicon layers ion-doped by boron. Studing the structure of the near-surface area in ion-doped epitaxial silicon by means of modern methods has shown that in the field of the first concentration maximum (the nearest one to a wafer surface), the fine-blocked silicon structure is localised. In the range of the second doping concentration maximum, the grid of dislocations with the variable period within one grid and consisting of 60° dislocations is found out. In the area of dislocation grids, oxygen atoms have been found out. The variable period in the grid is related with a change of mechanical stress and deformation distribution law in the plane of dopant diffusion front as dependent on the presence of initial defects in silicon

Genesis of initial defects in the process of monocrystalline silicon oxidation with subsequent scribing

The type, density, and distribution of defects in initial and oxidated monocrystalline silicon wafers were studied by modern methods. It was established that disordered silicon and stacking faults are basic defects in near-surface layers of oxidated monocrystalline silicon. It was shown that stacking faults are generated during the oxidation process, and the mechanism of their formation is connected with the defective layered structure of initial silicon wafers. It was established that defects of layered heterogeneity, on the one hand, lead to the formation of stacking faults and, on the other hand, prevent their propagation to the wafer bulk

Morphology and optical properties of SnO₂ nanofilms

Results of surface morphology and optical density investigations and the photoluminescence phenomenon were obtained for SnO₂ thin films. Films having nanosize of their grains ~ 10-15 nm were obtained using polymeric materials. Evaluation of a dimensional quantization is fulfilled by two methods: analytically using AFM data, and by means of optical density spectra; results obtained by these two methods are in a good agreement

Sensor based on a non-ideal heterojunction to indicate X-ray images

The sensor of optical image on the basis of non-ideal heterojunctions are investigated in detail. In this work, the opportunity to obtain the image in X-rays was investigated. It is established that investigated sensor is sensitive to soft X-ray radiation. Memory and accumulation of a signal at a room temperature, which is characteristic of the sensor at registration of images in visible light, take place for the images obtained in X-ray range, too, which makes it possible to apply such sensor in medicine and crystallography

Influence of internal parameters on the signal value in optical sensor based on the non-ideal heterostructure CdS-Cu₂S

The signal (defined by conductivity) of optical sensor based on CdS-Cu₂S heterostructure both at direct and alternative current strongly depends on barrier parameters that can change under exposure. It was stated that such parameter as resistance of space charge region considerably depends on its width at a constant barrier height, and this dependence is similar to linear shape. This behavior can indicate domination of tunnel multistep mechanisms in the studied structure, for instance, the mechanism of tunnel-jumping conductivity

Temperature dependence of luminescence pecularities in oxygen doped ZnTe films

Temperature dependence of luminescence intensity inherent to zinc telluride films prepared by the method of vacuum deposition and containing an oxygen impurity was investigated. The model explaining non-monotonous behaviour of curve temperature dependence for the "oxygen" band (λmax = 650 nm) is offered. According to this model, during quenching luminescence, the centers of a luminescence and those of the majority carriers capture participate. Determined are the values of the activation energy and concentration of the appropriate centers at which abnormal dependence of luminescence intensity on the temperature is observed

Вплив умов технології на формування центрів світіння у квантових точках CdS

У роботі представлені результати дослідження впливу процесу синтезу квантових точок сульфіду кадмію колоїдно-хімічним методом у водному розчині желатини на їх оптичні і люмінесцентні властивості. Показано, що для розуміння механізму утворення дефектів в КТ CdS при їх синтезі у водних розчинах необхідно враховувати результат протікання процесу гідролізу і залежність його продуктів від величини рН розчину. На підставі розрахунку молярної концентрації компонентів гідролізу солі кадмію Cd(NO3)2, зроблений висновок про типи власних дефектів, які обумовлюють спектр фотолюмінесценції КТ CdS, що спостерігається.The paper describes results of the research on the effect of the synthesis of cadmium sulfide quantum dots by the colloid-chemical method in an aqueous solution of gelatins on their optical and luminescent properties. It was shown that to understand the mechanism of the formation of defects in CdS QDs when they are synthesized in aqueous solutions of salts, it is necessary to take into account the result of the hydrolysis process and the dependence of its products on the pH of the solution. Based on the calculation of the molar concentration of the components of the hydrolysis of the cadmium salt Cd(NO3)2, the conclusion was drawn about the types of intrinsic defects that determine the observed photoluminescence spectrum of CdS QDs

Structure, spectroscopic and thermal characterization of bis(acetylacetonato) dichlorotin (IV) synthesized in aqueous solution

Bis(acetylacetonato)dichlorotin(IV) is synthesized from the aqueous solutions of tin(IV) chloride and acetylacetone followed by vacuum drying at room temperature. DTA/TGA, FTIR, UV-VIS, X-ray powder and single crystal, mass spectra and elemental analysis are performed to characterize the product. X-ray powder diffraction suggests that the sample may contain some impurities such as SnO, SnO₂ and Sn₂О₃ while the mass spectra indicates the existence of Sn(acac)₄, which is arguable due to the steric effect. Single crystal investigation reveals that the product synthesized in aqueous solution is Sn(acac)₂Cl₂, crystallized in monoclinic system in space group C2/c with unit cell constants a=13.983(2), b=7.8928(8), c=13.7889(19) Å and β =107.601(11)°, whose volume is 1.43 % smaller than the one synthesized in dry toluene.Дихлордиацетилацетонат олова (IV) синтезирован в водном растворе хлорида олова (IV) и ацетилацетона с последующей сушкой в вакууме при комнатной температуре. Свойства синтезированного продукта исследованы методами DTA/TGA, FTIR, UV-VIS, рентгеновской дифракции, масс-спектроскопии и элементного анализа. Согласно результатам рентгеновской дифракции порошков, образец может содержать немного примесей, таких как SnO, SnO₂ и Sn₂О₃, в то же время массовые спектры указывают на существование Sn(acac)₄, что является спорным из-за стерического эффекта. Рентгенографические исследования отдельных кристаллов показывают, что продуктом, синтезированным в водном растворе, является Sn(acac)₂Cl₂, кристаллизованный в моноклинной системе в пространственной группе C2/c с постоянными решетки a=13.983(2), b=7.8928(8), c=13.7889(19) Å , β =107.601(11)° и объемом на 1.43 % меньшим, чем объем вещества, синтезированного в сухом толуоле.Діхлордіацетилацетонат олова (ІV) синтезований у водному розчині хлориду олова (ІV) і ацетилацетона з наступним сушінням у вакуумі при кімнатній температурі. Властивості синтезованого продукту досліджені методами DTA/TGA, FTІ, UV-VІS, рентгенівської дифракції, мас-спектроскопії та елементного аналізу. Згідно з результатами рентгенівської дифракції порошків зразок може містити небагато домішок, таких як SnO, SnO₂ і Sn₂О₃, у той же час масові спектри вказують на існування Sn(acac)₄, що є суперечним внаслідок стеричного ефекту. Рентгенографічні дослідження окремих кристалів показують, що продуктом, синтезованим у водному розчині, є Sn(acac)₂Cl₂, кристалізований у моноклінній системі в просторовій групі C2/c із сталими гратки a=13.983(2), b=7.8928(8), c=13.7889(19) Å і β =107.601(11)° та об’ємом, на 1.43 % меншим за об’єм речовини, синтезованої в сухому толуолі