Bound oxygen influence on the phase composition and electrical properties of semi-insulating silicon films

The purpose of this work is to establish of the bound oxygen effect on the phase composition of the Semi-Insulating Polycrystalline Oxygen-doped Silicon (SIPOS) films by means of three independent methods: X-ray diffraction (XRD), Ultrasoft X-ray Emission Spectroscopy (USXES) and Raman spectroscopy, also on their electrophysical properties, depending on the relative oxygen content in the gas mixture flow (γ=N2O/SiH4) of the plasma reactor during the chemical vapor deposition of submicron SIPOS layers on monocrystalline silicon wafers. The increase in the oxygen content in SIPOS layers from γ=0 to maximum at γ=0.15 leads to the reduction of Si nanocrystals size from ~75 nm to 2–5 nm, submerged in amorphous matrix. Oxygen is contained in the bound form of silicon-oxygen clusters SiOSi3 type in the amorphous silicon matrix without SiO2 formation. These nonlinear qualitative and quantitative changes in the atomic structure of the SIPOS layers under the influence of bound oxygen increase not only the resistivity of the films by two orders of magnitude but also the activation energy of conductivity in comparison with silicon at the temperatures above room temperature. © 2020 Elsevier LtdRussian Foundation for Basic Research, RFBR: 19-42-363013MD-42.2019.2Ministry of Science and Higher Education of the Russian FederationThe reported study was funded by RFBR and Government of Voronezh region according to the research project № 19-42-363013.The part of work was carried out with the support of the Ministry of Science and Higher Education of Russia Federation under the grand No. FZGU-2020-0036 .In part of diagnostics of the structures the work of P.V. Seredin was supported by the RF President's Grants Council (Grant MD-42.2019.2)

ОСОБЕННОСТИ ЭЛЕКТРОННОГО СТРОЕНИЯ НАНОСЛОЕВ «КРЕМНИЙ–НА–ИЗОЛЯТОРЕ» И ИХ ВЗАИМОДЕЙСТВИЕ С ИЗЛУЧЕНИЕМ НАНОМЕТРОВОГО ДИАПАЗОНА

Structures with strained and unstrained silicon layers were studied by ultrasoft X−ray emission spectroscopy and X−ray absorption near edge structure spectroscopy with the use of synchrotron radiation techniques the SOI (silicon−on−insulator). Analysis of X−ray data has shown a noticeable transformation of the electron energy spectrum and local partial density of states distribution in valence and conduc- tion bands in the strained silicon layer of the SOI structure. USXES Si L2,3 spectra analysis revealed a decrease of the distance between the L′2v и L1v points in the valence band of the strained silicon layer as well as a shift of the first two maxima of the XANES first derivation spectra to the higher energies with respect to conduction band bottom Ec. At the same time the X−ray standing waves of synchrotron radiation (λ ~ 12−20 nm) are formed in the silicon−on−insulator structure with and without strains of the silicon layer. Moreover the synchrotron radiation grazing angle θ changing by 2° leads to a change of the electromagnetic field phase to the opposite. Методами ультрамягкой рентгеновской эмиссионной спектроскопии и спектроскопии ближней тонкой структуры края рентгеновского поглощения с использованием синхротронного излучения исследованы структуры КНИ (кремний−на−изоляторе) с растянутым и нерастянутым слоями кремния. Выявлена заметная перестройку электронно−энергетического спектра и локальной парциальной плотности состояний как в валентной зоне, так и в зоне проводимости растянутого слоя кремния структуры КНИ. На основе анализа Si L2,3 спектров USXES показано уменьшение энергетического расстояния между точками L′2v и L1v  в валентной зоне растянутого слоя кремния, в котором наблюдался и сдвиг первых двух максимумов первой производной спектра XANES в сторону больших энергий относительно дна зоны проводимости Ес. Обнаружено, что при этом стоячие рентгеновские волны синхротронного излучения нанометрового диапазона длин волн  (λ ~ 12—20 нм) формируются в структурах кремний−на−изоляторе как с растянутым, так и с нерастянутым нанослоем кремния. Более того, установлено, что изменение угла скольжения синхротронного излучения θ на 2° приводит к смене фазы электромагнитного поля на противоположную.

Structure and photoluminescence properties of SnO

One-dimensional (1D) SnO2 nanowires were synthesized from SnO powder by heat treatment of SnO powder under Ar gas flow at atmospheric pressure, with the next annealing on the air at 1000 °C. The morphology and microstructure of the single crystalline SnO2 nanowires are characterized by means of the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The band gaps of the products are ~(3.42–3.78 eV) determined from UV/visible absorption spectral results. The SnO2 nanowires show stable photoluminescence (PL) with one emission peak centred at around ~2 eV