Recently ferroelectric properties have been found in hafnia-based nanosized films. Such films are of the utmost interest for development of a universal memory, which combines the advantages of random access memory and flash memory. The paper studies optical properties of hafnia-zirconium oxide films H-fxZryO2 and lanthanum-alloyed hafnia-zirconium oxide films La:HfxZryO2. Fluctuations of thickness in HfxZryO2 do not exceed 3.5

A solution to the direct ellipsometry problem is presented for a single-layer model of an isotropic substrate–anisotropic film in the case of the orientation of the film optical axis in the plane of incidence. Analytical expressions for calculating the ellipsometric parameters of such a structure are obtained. A simple numerical algorithm is proposed for determining the ordinary ( n_o ) and extraordinary ( n_e ) refractive indices of a bulk crystal under various measurement conditions. The inverse problem of determining n_o , n_e , and the film thickness d when changing the azimuth of the optical axis is considered. The correlation of the required parameters for such a problem is discussed.

Представлено решение прямой задачи эллипсометрии для однослойной модели изотропная подложка - анизотропная плёнка в случае ориентации оптической оси плёнки в плоскости падения. Получены аналитические выражения для расчёта эллипсометрических параметров такой структуры. Предложен простой численный алгоритм определения обыкновенного ( no ) и необыкновенного (ne ) показателей преломления объёмного кристалла при различных условиях измерения. Рассматривается обратная задача определения no , ne и толщины плёнки d при изменении азимута оптической оси. Обсуждается проблема корреляции искомых параметров для такой задачи. A solution to the direct ellipsometry problem is presented for a single-layer model consisting of an isotropic substrate and an anisotropic film in the case of the orientation of the optical axis of the film in the plane of incidence. Analytical expressions for calculating the ellipsometric parameters of such a structure are obtained. A simple numerical algorithm is proposed for determining the ordinary ( no ) and extraordinary ( ne ) refractive indices of a bulk crystal under various measurement conditions. The inverse problem of determining no, ne, and film thickness d when changing the azimuth of the optical axis is considered. The correlation of the required parameters for such a problem is discussed.

A mechanism of transverse charge transfer through hexagonal boron nitride (h-BN) in a MIS structure has been studied. Experimental data for charge transfer have been analyzed in terms of different models of charge transfer in insulators. It has been shown that charge transfer in h-BN is described by the model of phonon-assisted tunneling between neutral traps. The thermal and optical energies of phonon-coupled traps in h-BN have been determined. Based on charge transfer measurements, XPS spectra, and the ab initio electronic structure of intrinsic defects in h-BN it has been found that boron–nitrogen divacancies are most probably responsible for charge transfer in h-BN and transfer is provided by electrons.

Recently ferroelectric properties have been found in hafnia-based nanosized films. Such films are of the utmost interest for development of a universal memory, which combines the advantages of random access memory and flash memory. The paper studies optical properties of hafnia-zirconium oxide films HfxZryO2 and lanthanum-alloyed hafnia-zirconium oxide films La : HfxZryO2. Fluctuations of thickness in HfxZryO2 do not exceed 3.5%, fluctuations of thickness in La : HfxZryO2 films --- 3.2%. Optical properties are analyzed based on effective-medium theory. According to effective-medium theory data, HfxZryO2 films contain 46% HfO2, 54% ZrO2, La : HfxZryO2 films contain 47.5% HfO2, 52.4% ZrO2, 2.5% La2O3. Keywords: ferroelectric, refraction index, spectral ellipsometry, effective-medium theory.

The thermal stability of silicon-on-insulator films with a thickness of 4.7  and 2.2 nm is studied as a function of annealing temperature in the range of Т = 800–1200°C by scanning electron microscopy and spectral ellipsometry. No signs of film melting were found; the films remain continuous over this annealing temperature range. A decrease in the thickness of the films and a change in their phase composition with an increase in temperature are discovered. According to the data of spectral ellipsometry, as the annealing temperature is increased, the content of the crystalline phase in the films decreases and the content of the amorphous phase increases. The activation energy of the process of film amorphization is estimated. The revealed properties are discussed from the viewpoint of diffusion of oxygen atoms into a silicon film and rearrangement of Si–Si bonds.

Non-stoichiometric silicon nitride SiN x , enriched with silicon, is a promising material for the non-volatile resistive memory development. The current studies devoted to investigation of the optical properties of SiN x synthesized in a low-pressure reactor at 800 o C at different ratios of dichlorosilane (SiH 2 Cl 2 ) to ammonia (NH 3 ). It was found that for films synthesized at SiH 2 Cl 2 /NH 3 =1/1, 1/2 and 1/3, the corresponding bandgap values are 3.83, 4.17 and 4.40 eV. At the same time, the corresponding values of the parameter x, found according to the theoretical dependence of the bandgap value on x for SiN x calculated from the first principles, are 1.26, 1.30 and 1.32. Thus, by increasing the SiH 2 Cl 2 /NH 3 ratio, it is possible to create non-stoichiometric SiN x films with a controlled silicon enrichment degree with high uniformity of chemical composition and thickness. Keywords: silicon nitride, memristor, absorption coefficient, ellipsometry, quantum chemical modeling.

Non-stoichiometric silicon nitride SiNx, enriched with silicon, is a promising material for the non-volatile resistive memory development. The current studies devoted to investigation of the optical properties of SiNx synthesized in a low-pressure reactor at 800 oC at different ratios of dichlorosilane (SiH2Cl2) to ammonia (NH3). It was found that for films synthesized at SiH2Cl2/NH3 ratio =1/1, 1/2 and 1/3, the corresponding bandgap values are 3.83, 4.17 and 4.40 eV. At the same time, the corresponding values of the parameter x, found according to the theoretical dependence of the bandgap value on x for SiNx calculated from the first principles, are 1.26, 1.30 and 1.32. Thus, by increasing the SiH2Cl2/NH3 ratio, it is possible to create non-stoichiometric SiNx films with a controlled silicon enrichment degree with high uniformity of chemical composition and thickness.

The thermal stability of silicon-on-insulator films with a thickness of 4.7 and 2.2 nm was studied as a function of the annealing temperature in the range T = 800−1200◦ C by scanning electron microscopy and spectral ellipsometry. No melting features of the films were found. The films remained continuous over the annealing temperature range. A decrease in the thickness of the films and a change in their phase composition with an increase in temperature were found. According to spectral ellipsometry, as the annealing temperature increased, the content of the crystalline phase in the films decreases, and the content of the amorphous one increases. The activation energy of the film amorphization was estimated. The revealed properties are discussed in the frame of the oxygen atom diffusion in the silicon films and in the rearrangement of Si-Si bonds.

The optical and electrochromic properties of thin films obtained by centrifugation from solutions containing ambipolar polyimides with pendant groups based on 9H-thioxanthene-9-one and its S-dioxide derivative are studied using spectral ellipsometry, spectrophotometry, and spectroelectrochemistry. It is shown that the spectral dependences of the refractive index n(E) and the absorption coefficient α(E) as well as the electrochromic properties of polyimide thin films under electrochemical reduction and oxidation conditions strongly depend on the type of the pendant group. Based on the estimates of the band gap Eg a conclusion is made about the possible promising use of thin films of polyimides as working layers in memristors of a new type. Keywords: memristors, dielectric films, ambipolar polyimides, ellipsometry, electrochromism.

Термическая стабильность пленок кремний-на-изоляторе толщиной 4.7 и 2.2 нм исследовалась в зависимости от температуры отжига в интервале T=800-1200oС методами сканирующей электронной микроскопии и спектральной эллипсометрии. Никаких признаков плавления пленок не наблюдалось, пленки оставались протяженными в указанном интервале температур. Обнаружено уменьшение толщины пленок и изменение их фазового состава с ростом температуры. По данным спектральной эллипсометрии, с увеличением температуры отжига доля кристаллической фазы в пленках уменьшается, а доля аморфной растет. Определена энергия активации процесса аморфизации пленок. Обнаруженный эффект обсуждается с точки зрения диффузии атомов кислорода в пленку кремния и перестройки Si-Si-связей. Ключевые слова: кремний-на-изоляторе, термическая стабильность, наноструктуры, аморфизация.

Методами спектральной эллипсометрии, спектрофотометрии и спектроэлектрохимии исследованы оптические и электрохромные свойства тонких пленок, полученных методом центрифугирования из растворов, содержащих амбиполярные полиимиды с пендантными группами на основе 9H-тиоксантен-9-она и его S-диоксидного производного. Показано, что спектральные зависимости показателя преломления и коэффициента поглощения, а также электрохромные свойства тонких пленок полиимидов в условиях электрохимического восстановления и окисления сильно зависят от типа пендантной группы. На основании оценок ширины запрещенной зоны сделан вывод о возможном перспективном использовании тонких пленок полиимидов в качестве рабочих слоев в мемристорах нового типа. Ключевые слова: мемристоры, диэлектрические пленки, амбиполярные полиимиды, эллипсометрия, электрохромизм.

The optical properties and composition of thermal silicon oxide thin films processed in a hydrogen electron cyclotron resonance plasma have been studied by ellipsometry, quantum-chemical modeling, and photoluminescence spectroscopy. It has been found that the plasma processing of the films leads to their oxygen depletion and the formation of nonstoichiometric oxide SiOx (2). The parameter x of the obtained SiOx films has been determined by comparing the experimental spectral dependence of the refractive index with the dependence obtained theoretically using the ab initio calculation. It is shown that an increase in the time of processing of thermal dioxide SiO2 in a hydrogen plasma leads to an increase in the refractive index of the film, as well as in the degree of its oxygen depletion. The dependence of the parameter x of the investigated films on the hydrogen plasma processing time is plotted.

Using the methods of ellipsometry, quantum chemical modeling, and photoluminescent spectroscopy, the optical properties and composition of thin films of thermal silicon oxide processed in a hydrogen electron-cyclotron resonance plasma are studied. It has been established that treatment of films in plasma leads to their depletion in oxygen and the formation of non-stoichiometric oxide SiOx <2. By comparing the experimental spectral dependence of the refractive index with the theoretically calculated from the first principles, the values ​​of the parameter x in the obtained SiOx films are determined. It was shown that an increase in the processing time of thermal SiO2 in hydrogen plasma leads to an increase in the refractive index of the film, as well as the degree of depletion of the film with oxygen. For the studied films, the dependence of the value of the parameter x on the treatment time in a hydrogen plasma is constructed.

Diagnostic pilot monitoring of the groups of healthy patients and patients with colorectal cancer (CRC) at different stages of the disease was carried out using Raman spectroscopy (RS) and measuring the state of polarized light near the conditions of observation of surface plasmon resonance (SPR). The reaction of the blood serum antigens with antibodies to serum M2 pyruvate kinase (M2-PK) nears the conditions of observation of SPR was used for diagnosing; for this, the Ellipse-SPEC spectral ellipsometric complex created at the Rzhanov Institute of Semiconductor Physics (Siberian Branch, Russian Academy of Sciences) and having a high sensitivity, accuracy, and nondestructive nature of the effect on the studied sample, was used in the work. The peak intensities at 1005, 1157, and 1520 cm –1 in Raman spectra in CRC patients as compared with healthy individuals (as well as the intensity of surface plasmon resonance) were significantly lower, correlating with the stage of the disease and the presence of metastases; this allows to consider these optical methods for studying the blood serum as promising diagnostic approaches in diagnosis CRC, including in the early stages of the disease.

Ключевым параметром, определяющим качество получаемых структур в методе молекулярнолучевой эпитаксии (МЛЭ), является температура подложки. Существуют различные методы контролятемпературы в условиях низкотемпературного синтеза МЛЭ, но каждый из них имеет своиограничения [1, 2], и они не решают полностью поставленную задачу. Сделанные нами ранее оценкивозможности лазерной эллипсометрии для контроля температуры показали, что точность методасоставляет 20-30С и не удовлетворяет требованиям технологии [2].В данной работе предложен метод in situ контроля предростовой температуры CdTe на основеспектральной эллипсометрии, чувствительность которого на порядок превышает приведённую вышеоценку. Для этого нами разработан, изготовлен и смонтирован на модуль роста КРТ спектральныйэллипсометр (=350-1100 нм), конструкция которого оптимизирована под геометрию используемойвакуумной камеры.Для измерения температуры используются характеристики спектров () и () вблизикритических точек зонной структуры CdTe, соответствующих краю поглощения Е0 (0(300 К)830 нм) имежзонному переходу Е1 (1(300 К)370 нм). Вблизи Е0 появляются интерференционные осцилляции и , а вблизи E1 наблюдается максимум в спектре (). Спектральное положение критических точекзависит от температуры. Проведённая нами предварительно ex-situ калибровка на образцах CdTeпоказала, что чувствительность составляет 0.22 нм/C для Е0 и 0.067 нм/C для Е1. Предложен методопределения Е0 по затуханию амплитуд интерференционных осцилляций, который позволяетнаходить значение 0 с точностью 0.5 нм, что соответствует точности определения температуры 3С.

AbstractThe anodic oxidation rate of silicon-on-insulator films fabricated by hydrogen transfer is studied as a function of the temperature of subsequent annealing. It is established that the oxidation rate of transferred silicon-on-insulator films is five times lower compared to the oxidation rate of bulk single-crystal silicon samples. The oxidation rate increases, as the annealing temperature is elevated in the range 700–1100°C and as the depth of gradually removed anode-oxidized layers is increased. The results obtained in the study are attributed to an increase in the efficiencies of the anodic current and oxygen–silicon interatomic interaction due to the annealing of defects and due to release of hydrogen from the bound state, respectively. The formation of hydrogen bubbles in the surface region of silicon due to the diffusion of hydrogen, released in the process of the oxidation reaction, towards micropores in the silicon-on-insulator layer is detected.

The anodic oxidation rate of silicon-on-insulator films fabricated by hydrogen transfer is studied as a function of the temperature of subsequent annealing. It is established that the oxidation rate of transferred silicon-on-insulator films is five times lower compared to the oxidation rate of bulk single-crystal silicon samples. The oxidation rate increases, as the annealing temperature is elevated in the range 700–1100°C and as the depth of gradually removed anode-oxidized layers is increased. The results obtained in the study are attributed to an increase in the efficiencies of the anodic current and oxygen–silicon interatomic interaction due to the annealing of defects and due to release of hydrogen from the bound state, respectively. The formation of hydrogen bubbles in the surface region of silicon due to the diffusion of hydrogen, released in the process of the oxidation reaction, towards micropores in the silicon-on-insulator layer is detected.