The problems of in situ ellipsometric control during the growth of ZnTe and CdTe buffer layers intended for cadmium-mercury-tellurium epitaxy are considered. It has been established that for 20 nm ZnTe layers the spectral dependences of the optical constants near the absorption edge are smoothed, which indicates the presence of structural defects in the film. It has been shown that the microrelief of the CdTe growth surface is a criterion for the structural perfection of the layers and can be measured using an ellipsometer both at the early stages and during steady-state growth.

In situ temperature control is required to obtain HgCdTe layers of high crystalline perfection by molecular beam epitaxy. To solve this problem, we used spectroscopic ellipsometry. Various methods have been developed for measuring the temperature before the start of epitaxy. They are based on the analysis of different regions of the ellipsometric spectra of the CdTe buffer layer. An experimental comparison of the suggested methods shows that the temperature measurement accuracy is several degrees, and the sensitivity reaches fractions of a degree. At the stage of stationary growth of layers, it is possible to determine the change in temperature and composition from the kinetics of ellipsometric spectra. Ellipsometric measurements made during the growth of HgCdTe with a sharp change in the heating regime showed correlated changes in both temperature and composition.

An ellipsometric technique has been developed which makes it possible to observe changes in the composition and temperature of cadmium--mercury--tellurium layers during their growing by molecular beam epitaxy. The technique was tested for diagnostics the variations of the composition and the temperature during layer growth in the mode of constant power of the substrate heater and with its sharp change. It was found that the drop in power and a following decrease in the growth temperature were also accompanied by a monotonic decrease in the composition. In the case of a constant heater power, a slight increase in the sample temperature was observed with an almost unchanged composition of the growing layer. Keywords: ellipsometry, mercury--cadmium--telluride, in situ control, epitaxial growth, temperature.

В последнее время обнаружено наличие сегнетоэлектрических свойств наноразмерных пленок на основе оксида гафния. Такие пленки представляют большой интерес для разработки универсальной памяти, которая сочетает преимущества оперативной и флэш-памяти. В работе изучаются оптические свойства пленок оксида гафния-циркония Hf x Zr y O 2 и пленок оксида гафния-циркония, легированных лантаном, La : Hf x Zr y O 2 . Флуктуации толщины пленок Hf x Zr y O 2 не превышают 3.5%, флуктуации толщины пленок La : Hf x Zr y O 2 --- 3.2%. Оптические свойства анализируются на основе теории эффективной среды. По данным теории эффективной среды пленки Hf x Zr y O 2 содержат 46% HfO 2 , 54% ZrO 2 , пленки La : Hf x Zr y O 2 содержат 47.5% HfO 2 , 52.4% ZrO 2 , 2.5% La 2 O 3 . Ключевые слова: сегнетоэлектрик, показатель преломления, спектроэллипсометрия, теория эффективной среды.

Using the method of dielectrophoresis an optical cell detection system in an inhomogeneous alternating electric field, the electrical and viscoelastic parameters of red blood cells in the frequency range from 5 × 104 to 1 × 106 MHz have been studied in 129 patients with colorectal cancer (CRC) of various stages of the disease, 25 people with adenomatous polyps, and 35 people in the comparison group. It has been shown that the values of the physical characteristics of red blood cells significantly differ both when comparing the control groups and the patients with adenomatous polyps and the patients with early stages of CRC and when comparing the patients with different stages of the oncological process with each other. The construction of SHAP graphs based on the electrical and viscoelastic parameters of red blood cells has allowed us to achieve 100% diagnostic accuracy in distinguishing patients with adenomatous polyps and early stages of CRC from healthy individuals, 98.7% accuracy—in differentiating the patients with polyps from the patients with early stages of CRC, and 91.9% accuracy—in distinguishing early and late stages of CRC. The results obtained demonstrate the high potential of the proposed method for screening and diagnosing CRC.

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 problem of in situ temperature control during the growth of epitaxial layers of HgCdTe by molecular beam epitaxy is considered. Various approaches to solving the problem using spectroscopic ellipsometry are proposed. They are based on the temperature dependence of the optical constants spectra of the CdTe buffer layer and the growing HgCdTe layer. The results of experimental testing of these methods are presented, which show that the temperature measurement accuracy is several degrees, and the sensitivity reaches fractions of a degree. At the stage of stationary growth, it is possible to determine the change not only in the temperature, but also in the composition of the growing layer from the ellipsometric spectra.

A parametric model describing the spectra of optical constants n(λ) and k(λ) of a Hg1 – xCdxTe (MCT) solid solution for the x values in the range from 0.2 to 0.4 is developed. This model is based on empirical data measured in situ during the epitaxial growth of solid-solution layers. Several versions of application of the obtained model for in situ real-time determination of the MCT composition have been considered. A technique for determining the composition using spectral ellipsometric measurements is proposed, which ensures the error of no more than δx = ±0.0035.

На основе проведeнных in situ и ex situ эллипсометрических измерений найдены спектральные зависимости температурной чувствительности оптических постоянных Hg1-xCdxTe --- dn(λ) и dk(λ) для серии образцов разного состава в диапазоне от 0.160 до 0.327. Эксперименты были проведены в процессе остывания выращенных образцов в вакуумной камере. Установлено, что полученные зависимости dn и dk хорошо аппроксимируются суммой трeх осцилляторов Лоренца с добавлением дисперсионных слагаемых формулы Коши. Предложена параметрическая модель, которая описывает чувствительности dn(λ) и dk(λ) для произвольного состава x в указанном диапазоне вблизи температуры роста. Проведенные ex situ температурные измерения вблизи комнатной температуры коррелируют с данными высокотемпературных измерений. Полученные результаты актуальны для разработки эллипсометрических методов контроля in situ процессов роста слоeв Hg1-xCdxTe. Ключевые слова: кадмий-ртуть-теллур, эллипсометрия, спектры оптических констант, температурная чувствительность, молекулярно-лучевая эпитаксия.

С помощью метода диэлектрофореза в неоднородном переменном электрическом поле при использовании оптической системы детекции клеток проведено исследование электрических и вязкоупругих параметров эритроцитов в частотном диапазоне от 5·104 до 1·106 MHz у 129 больных с колоректальным раком (КРР) различных стадий развития заболевания, 25 человек с аденоматозными полипами и 35 лиц группы сравнения. Показано, что величины физических характеристик эритроцитов значимо различаются как при сопоставлении групп контроля и пациентов с аденоматозными полипами и больных с ранними стадиями КРР, так и при сравнении пациентов с различными стадиями онкологического процесса между собой. Построение SHAP-графиков на основе электрических и вязкоупругих параметров эритроцитов позволило достичь 100% диагностической точности при различении пациентов с аденоматозными полипами, ранними стадиями КРР от здоровых лиц, 98.7% точности --- при дифференцировании пациентов с полипами от больных с ранними стадиями КРР, 91.9% точности --- при различении ранних и поздних стадий КРР. Полученные результаты демонстрируют высокий потенциал предложенного метода для скрининга и диагностики КРР. Ключевые слова: диэлектрофорез, эритроциты, электрические и вязкоупругие параметры, диагностика, колоректальный рак, аденоматозные полипы, SHAP-графики.

Low temperature in situ control in the technology of HgCdTe layers growing by MBE is a key requirement for obtaining structures of high quality. Spectroscopic ellipsometry seems to be one of the suitable technique for solving this problem. The present paper proposes ellipsometric methods for determining the temperature in the process of pre-epitaxial heat treatment of the samples. The proposed methods are based on the temperature dependence of the optical constants spectra of the CdTe buffer layer. The first method uses the temperature shift of the absorption edge, which is determined from the onset of interference oscillations. It turned out to be resistant to experimental errors and its accuracy proved to be 3-5 degrees C. The second method is based on comparing the measured and reference spectra. It is much more sensitive to the temperature, but depends strongly on the accuracy of ellipsometric measurements. The combined use of both methods ensures a temperature sensitivity of the order of 1 degrees C and an accuracy of 3-5 degrees C.

Based on in situ and ex situ ellipsometric measurements, the spectral dependences of the temperature sensitivity of the optical constants Hg 1 –   x Cd х Te— dn (λ) and dk (λ) have been found for a series of samples of different compositions in the range from 0.160 to 0.327. The experiments were performed during cooling of the grown samples in a vacuum chamber. It has been found that the obtained dn and dk dependences can be well approximated by the sum of three Lorentz oscillators with the addition of the dispersion terms of the Cauchy formula. A parametric model that describes the sensitivities dn (λ) and dk (λ) for an arbitrary composition x in the specified range near the growth temperature has been proposed. Ex situ temperature measurements performed near room temperature correlate with the data of the high-temperature measurements. The results obtained are relevant for the development of ellipsometric control methods in situ of Hg 1 –   x Cd х Te layer growth processes.

Разработана эллипсометрическая методика, позволяющая наблюдать за изменениями состава и температуры слоeв кадмий--ртуть--теллур в процессе их выращивания методом молекулярно-лучевой эпитаксии. Методика опробована для диагностики состава и температуры при выращивании слоeв в режиме постоянной мощности нагревателя подложки и при еe резком изменении. Установлено, что падение мощности и последующее уменьшение температуры роста сопровождается также монотонным уменьшением состава. В случае постоянной мощности нагревателя наблюдается незначительное увеличение температуры образца при практически неизменном составе растущего слоя. Ключевые слова: эллипсометрия, кадмий--ртуть--теллур, HgCdTe, состава, in situ контроль температуры, эпитаксиальный рост.

The luminescent and optical properties of materials based on zirconium(IV) oxide grown by crystallization of ZrO2 melts with 0, 2.0, 2.5, 2.8, and 3.7 mol % of Y2O3 are studied. Using Raman spectroscopy, it is found that this material with the Y2O3 concentration below 2 mol % is mainly a monoclinic ZrO2 phase. The photoluminescence spectra of these crystals contain a blue–green band peaking at an energy of 2.4 eV. This fact in combination with the specific features of the refractive index and absorption coefficient dispersions indicates the presence of high concentrations of oxygen vacancies and polyvacancies in the samples. At higher concentrations of Y2O3 in the mixture, the tetragonal ZrO2 modification becomes dominant in the materials under study and the blue–green luminescence intensity decreases. The experimental optical spectra are analyzed in comparison with the ab initio calculated spectra for ideal ZrO2 crystals in the cubic, tetragonal, and monoclinic phases.

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 SiCOH low-k dielectric film was grown on Si substrate using plasma enhanced chemical vapor deposition method. Atomic structure and optical properties of the film were studied with the use of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) absorption spectroscopy, Raman spectroscopy and ellipsometry. Analysis of XPS data showed that the low-k dielectric film consists of Si-O4 bonds (83%) and Si-SiO3 bonds (17%). In FTIR spectra some red-shift of Si-O-Si valence (stretching) vibration mode frequency was observed in the low-k dielectric film compared with the frequency of this mode in thermally grown SiO2 film. The peaks related to absorbance by C-H bonds were observed in FTIR spectrum. According to Raman spectroscopy data, the film contained local Si-Si bonds and also C-C bonds in the s-p3 and s-p2 hybridized forms. Scanning laser ellipsometry data show that the film is quite homogeneous, homogeneity of thickness is ~ 2.5%, and homogeneity of refractive index is ~ 2%. According to analysis of spectral ellipsometry data, the film is porous (porosity is about 24%) and contains clusters of amorphous carbon (~ 7%).

The luminescent and optical properties of materials based on zirconium oxide obtained by the crystallization of ZrO2 with 0, 2.0, 2.5, 2.8, and 3.7% mol Y2O3 melts were studied. Using Raman spectroscopy, it was found that when the Y2O3 content in the mixture is less than 2 % mol. the material is predominantly a monoclinic ZrO2 structure. For such crystal, a blue-green band with the maximum energy of 2.4 eV was observed in the photoluminescence spectra. This fact, together with the peculiarities of the refractive index and absorption dispersion spectra, indicates the presence of a high concentration of oxygen vacancies and polyvacancies in the sample. With a higher content of Y2O3 in the mixture, the tetragonal modification of ZrO2 dominates in the studied materials; the intensity of blue-green luminescence decreases. A comparative analysis of experimental optical spectra with the first-principle calculations for ideal ZrO2 crystals in the cubic, tetragonal and monoclinic phases was performed.

A parametric model describing the spectra of the optical constants Hg1-xCdxTe n( lam) and k(lam) for x values in the range from 0.2 to 0.4 is presented. The Model is based on empirical data measured in situ during epitaxial growth of the compound layers. Variants of using the obtained model for determining the composition of MCT in situ in real time are considered. A method for determining the composition based on spectral ellipsometric measurements is proposed, which provides an accuracy no worse than (del)x=±0.0035.

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.