Functional Nanomaterials and Devices VII

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Authors: O.V. Naumova, B. Fomin, V.P. Popov, Victor Strelchuk, A. Nikolenko, A.N. Nazarov
Abstract: Properties of Si/buried oxide (BOX) systems with bonded interface in silicon-on-insulator (SOI) wafers were studied in this paper. Results show impact of the starting Si material - Czochralski (Cz) or float-zone (Fz) grown silicon on the electron mobility (μe) and BOX charge behavior in ultrathin SOI layers. In particular, there were found: 1) the μe ~ Ne-0.3 dependencies at the electron density Ne in the range of 4х (1011-1012) cm-2 in accumulation Cz-SOI layers with the μe degradation when Si thickness decreases from 20 to 9 nm, and 2) the ~ Ne-0.6 behavior of mobility with no degradation in Fz-SOI layers. Raman spectroscopy shows the structural modification of Cz-SOI layers. An origin of degradation of the electrical and structural properties for ultrathin SOI layer is discussed.
Authors: V.S. Lysenko, Y.V. Gomeniuk, S.V. Kondratenko, Ye.Ye. Melnichuk, Y.N. Kozyrev, C. Teichert
Abstract: Crystalline germanium nanoclusters (NCs) are grown by a molecular-beam epitaxy technique on chemically oxidized Si (100) surface at 700oC. Deposition of silicon on the surface with Ge nanoclusters leads to surface reconstruction and formation of polycrystalline diamond-like Si coverage, while nanoclusters core becomes tetragonal SiGe alloy. Possible mechanisms for nanoclusters growth are discussed. Selective photoexcitation of Ge or SiGe nanoclusters or space-charge layer of underlying Si allows to observe two non-equilibrium steady-states with higher and lower conductivity values as compared to the equilibrium one. The persistent photoconductivity (PPC) behaviour was observed after excitation of electron-hole pairs in Si (001) substrate. This effect may be attributed to spatial carrier separation by macroscopic fields in the depletion layer of the near-surface Si. Decreasing of surface conductivity, driven by optical recharging of NCs and Si/SiO2 interface states, is observed in the spectral range from 0.6 to 1.0 eV. Conductivity drop is discussed in the terms of hole accumulation by Ge-NC states enhancing the local-potential variations and, therefore, decreasing the surface conductivity of p-Si.
Authors: N.P. Garbar, Valeriya N. Kudina, V.S. Lysenko, S.V. Kondratenko, Yu.N. Kozyrev
Abstract: Low-frequency noise of the structures with Ge-nanoclusters of rather high surface density grown on the oxidized silicon surface is investigated for the first time. It was revealed that the 1/f γ noise, where γ is close to unity, is the typical noise component. Nevertheless, the 1/f γ noise sources were found to be distributed nonuniformly upon the oxidized silicon structure with Ge-nanoclusters. The noise features revealed were analyzed in the framework of widely used noise models. However, the models used appeared to be unsuitable to explain the noise behavior of the structures studied. The physical processes that should be allowed for to develop the appropriate noise model are discussed.
Authors: Dmitry Osintsev, V. Sverdlov, Siegfried Selberherr
Abstract: We consider the impact of the surface roughness and phonon induced relaxation on transport and spin characteristics in ultra-thin SOI MOSFET devices. We show that the regions in the momentum space, which are responsible for strong spin relaxation, can be efficiently removed by applying uniaxial strain. The spin lifetime in strained films can be improved by orders of magnitude, while the momentum relaxation time determining the electron mobility can only be increased by a factor of two.
Authors: Tamara Rudenko, R. Yu, S. Barraud, K. Cherkaoui, P. Razavi, G. Fagas, A.N. Nazarov
Abstract: The electron mobility in highly-doped junctionless (JL) nanowire (NW) silicon-on-isulator (SOI) MOSFETs with various nanowire widths is experimentally studied and analyzed. The evidence for the considerable enhancement of the effective electron mobility in narrow NW devices as compared to counterpart planar (wide) devices, having the same film thickness and doping, and as compared to the bulk silicon mobility with the same doping is presented. This mobility enhancement increases with decreasing the NW width. The reason for this effect is considered to be reduction of the impurity Coulomb scattering in narrow NW MOSFETs due to: (i) the reduced depletion-layer width; (ii) stronger screening of ionized impurities; (iii) the reduced number of neighbor ionized doping atoms per each free carrier in very narrow NWs. These results are of great importance since mobility degradation due to high doping was considered to be one of the most important limitations of the JL NW MOSFETs.
Authors: V.I. Holota, Igor Kogut, Anatoly Druzhinin, Y. Khoverko
Abstract: A structure for single photon detection is analyzed. A special shape of photon detector electrodes on local 3D SOI structure is proposed. The structure of photon detector with a vertical local SOI MOS transistor is designed.
Authors: Anatoly Druzhinin, Yu. Khoverko, Igor Kogut, R. Koretskii
Abstract: The low temperature studies of SOI-structures have been carried out in a temperature range of 4.2÷300K at magnetic fields up to 14T. The samples with initial boron concentration of about 2.41018сm-3 have been investigated. The results of the studies of SOI-structure conductance at low temperatures in the range of hopping conductance and a possibility to use this material in sensors are analyzed.
Authors: A.N. Nazarov, S.O. Gordienko, P.M. Lytvyn, A.A. Stadnik, Y.Y. Gomeniuk, A.V. Vasin, A.V. Rusavsky, T.M. Nazarova, V.S. Lysenko
Abstract: The paper describes emission properties of a new nanostructured material carbon-rich amorphous silicon carbide (a-SiC) deposited on silicon wafer. Proposed material technology demonstrates that the field enhancement factor of the electron emission of this material can reach 1000 with the current density of about 1x10-3A/cm2 and efficiency of electron emission ~10%. A good correlation between the charge transfer through the a-SiC layer and electron emission from the material in high vacuum is observed.
Authors: Andrey Sarikov, M. Voitovych, Igor Lisovskyy, V. Naseka, A. Hartel, D. Hiller, S. Gutsch, M. Zacharias
Abstract: This work is devoted to determination of characteristics of hydrogen effusion from SiH bonds in Si rich silicon oxynitride (SRON) films, obtained by plasma enhanced chemical vapor deposition, as a result of thermal anneals at temperatures from 400 to 800°C. The values of the concentrations of SiH bonds in HSi (Si3nOn) (0 n 3) complexes contributing to the structure of SRON films are obtained from the analysis of infrared absorption spectra in the range of 2000-2400 cm1. The kinetics of the decrease of SiH concentrations as a result of anneals is described in the framework of a model with distributed activation energy of hydrogen emission. The median value and the mean-square deviation of this distribution as well as the attempt frequencies of SiH bond breaks are determined from the comparison of experimental and calculated SiH concentrations in SRON films. These characteristics are compatible with such characteristics found for the case of the depassivation of PbH centers at the Si/SiO2 interfaces. Obtained results are useful for the controlled formation of the layers of Si nanocrystals in dielectric matrix for Si based tandem solar cells applications.

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