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1.
Metal–organic chemical vapour deposition growth of titanium oxide on moderately pre-oxidised Si(1 1 1) using the titanium(IV) isopropoxide precursor has been studied for two different growth modes, reaction-limited growth at 300 °C and flux-limited growth at 500 °C. The interfacial properties have been characterized by monitoring synchrotron radiation excited Si 2p photoemission spectra. The cross-linking from oxidised Si to bulk Si after TTIP exposure has been found to be very similar to that of SiOx/Si(1 1 1). However, the results show that the additional oxidation of Si most probably causes a corrugation of the SiOx/Si interface. Those conclusions are valid for both growth modes. A model is introduced in which the amorphous interface region is described as (TiO2)x(SiO2)y where x and y changes linearly and continuously over the interface. The model quantifies how (TiO2)x(SiO2)y mixing changes the relative intensities of the signals from silicon oxide and silicon. The method can be generalised and used for the analyses of other metal-oxides on silicon.  相似文献   

2.
高明  杜汇伟  杨洁  赵磊  徐静  马忠权 《中国物理 B》2017,26(4):45201-045201
The damage on the atomic bonding and electronic state in a SiO_x(1.4-2.3 nm)/c-Si(150 μm) interface has been investigated.This occurred in the process of depositing indium tin oxide(ITO) film onto the silicon substrate by magnetron sputtering.We observe that this damage is caused by energetic particles produced in the plasma(atoms,ions,and UV light).The passivation quality and the variation on interface states of the SiO_x/c-Si system were mainly studied by using effective minority carrier lifetime(τ_(eff)) measurement as a potential evaluation.The results showed that the samples' τ_(eff)was reduced by more than 90%after ITO formation,declined from 107 μs to 5 μs.Following vacuum annealing at 200 ℃,the τ_(eff) can be restored to 30 μs.The components of Si to O bonding states at the SiO_x/c-Si interface were analyzed by x-ray photoelectron spectroscopy(XPS) coupled with depth profiling.The amorphous phase of the SiO_x layer and the "atomistic interleaving structure" at the SiO_x/c-Si interface was observed by a transmission electron microscope(TEM).The chemical configuration of the Si-O fraction within the intermediate region is the main reason for inducing the variation of Si dangling bonds(or interface states) and effective minority carrier lifetime.After an appropriate annealing,the reduction of the Si dangling bonds between SiO_x and near the c-Si surface is helpful to improve the passivation effect.  相似文献   

3.
a-Si/insulator multilayers have been deposited on (0 0 1) Si by electron gun Si evaporation and periodic electron cyclotron resonance plasma oxidation or nitridation. Exposure to an O or N plasma resulted in the formation of a thin SiO2 and SiNx layer whose thickness was self-limited and controlled by process parameters. For thin-layer (2 nm) Si/SiO2 and Si/SiNx multilayers no visible photoluminescence (PL) was observed in most samples, although all exhibited weak “blue” PL. For the nitride multilayers, annealing at 750°C or 850°C induced visible PL that varied in peak energy with Si layer thickness. Depth profiling of a-Si caps on thin insulating layers revealed no detectable contamination for the SiNx layers, but substantial O contamination for the SiO2 films.  相似文献   

4.
Silicon nanocrystals have been synthesized in SiO2 matrix using Si ion implantation. Si ions were implanted into 300-nm-thick SiO2 films grown on crystalline Si at energies of 30–55 keV, and with doses of 5×1015, 3×1016, and 1×1017 cm−2. Implanted samples were subsequently annealed in an N2 ambient at 500–1100°C during various periods. Photoluminescence spectra for the sample implanted with 1×1017 cm−2 at 55 keV show that red luminescence (750 nm) related to Si-nanocrystals clearly increases with annealing temperature and time in intensity, and that weak orange luminescence (600 nm) is observed after annealing at low temperatures of 500°C and 800°C. The luminescence around 600 nm becomes very intense when a thin SiO2 sample is implanted at a substrate temperature of 400°C with an energy of 30 keV and a low dose of 5×1015 cm−2. It vanishes after annealing at 800°C for 30 min. We conclude that this luminescence observed around 600 nm is caused by some radiative defects formed in Si-implanted SiO2.  相似文献   

5.
A method for the fabrication of luminescent Si nanoclusters in an amorphous SiO2 matrix by ion implantation and annealing, and the detailed mechanisms for the photoluminescence are reported. We have measured the implanted ion dose, annealing time and excitation energy dependence of the photoluminescence from implanted layers. The samples were fabricated by Si ion implantation into SiO2 and subsequent high-temperature annealing. After annealing, a photoluminescence band below 1.7 eV has been observed. The peak energy of the photoluminescence is found to be independent of annealing time and excitation energy, while the intensity of the luminescence increases as the annealing time and excitation energy increase. Moreover, we found that the peak energy of the luminescence is strongly affected by the dose of implanted Si ions especially in the high dose range. These results indicate that the photons are absorbed by Si nanoclusters, for which the band-gap energy is modified by the quantum confinement effects, and the emission is not simply due to direct electron–hole recombination inside Si nanoclusters, but is related to defects probably at the interface between Si nanoclusters and SiO2, for which the energy state is affected by Si cluster–cluster interactions. It seems that Si nanoclusters react via a thin oxide interface and the local concentrations of Si nanoclusters play an important role in the peak energy of the photoluminescence.  相似文献   

6.
Kapil Dev  E. G. Seebauer   《Surface science》2004,550(1-3):185-191
Experiments employing photoreflectance spectroscopy have uncovered band bending due to electrically active defects at the Si(1 1 1)–SiO2 interface after sub-keV Ar+ ion bombardment. The band bending of about 0.5 eV resembles that for Si(1 0 0)–SiO2, and both interfaces exhibit two kinetic regimes for the evolution of band bending upon annealing due to defects healing. The healing takes place about an order of magnitude more quickly at the (1 1 1) interface, however, probably because of less fully saturated bonding and higher compressive stress.  相似文献   

7.
NiO/Co and NiO/Ni80Fe20 bilayers were prepared at 293 onto SiO2(1 0 1)/Si(1 1 1) and glass substrates using UHV (5×10−10 mbar) RF/DC magnetron sputtering. Results on magnetic measurements showed that the exchange biasing and coercive fields are inversely proportional to the Co and Ni80Fe20 (Py) layer thickness down to 2 nm. A maximal RT coupling energy for the NiO–Co and NiO–Py interface was estimated as 0.04 and 0.03 mJ/m2 for the samples prepared onto SiO2(1 0 1)/Si(1 1 1) substrates.  相似文献   

8.
A simple simulation scheme that simultaneously describes the growth kinetics of SiO2 films at the nanometer scale and the SiOx/Si interface dynamics (its extent, and spatial/temporal evolution) is presented. The simulation successfully applies to experimental data in the region above and below 10 nm, reproduces the Deal and Grove linear-parabolic law and the oxide growth rate enhancement in the very thin film regime (the so-called anomalous region). According to the simulation, the oxidation is governed mainly by two processes: (a) the formation of a transition suboxide layer and (b) its subsequent drift towards the silicon bulk. We found that it is the superposition of these two processes that produces the crossover from the anomalous oxidation region behavior to the linear-parabolic law.  相似文献   

9.
We have studied the influence of the hydrostatic pressure during annealing on the intensity of the visible photoluminescence (PL) from thermally grown SiO2 films irradiated with Si+ ions. Post-implantation anneals have been carried out in an Ar ambient at temperatures Ta of 400°C and 450°C for 10 h and 1130°C for 5 h at hydrostatic pressures of 1 bar–15 kbar. It has been found that the intensity of the 360, 460 and 600 nm PL peaks increases with rising hydrostatic pressure during low-temperature annealing. The intensity of the short-wavelength PL under conditions of hydrostatic pressure continues to rise even at Ta=1130°C. Increasing Ta leads to a shift in the PL spectra towards the ultraviolet range. The results obtained have been interpreted in terms of enhanced, pressure-mediated formation of ≡Si–Si≡ centres and small Si clusters within metastable regions of the ion-implanted SiO2.  相似文献   

10.
Si particles embedded in an SiO2 matrix were obtained by co-sputtering of Si and SiO2 at various deposition temperatures Td (200–700°C) and annealing at different temperatures Ta (900–1100°C). The systems were characterized by X-ray photoelectron, Raman scattering, infrared absorption and photoluminescence spectroscopy techniques. The results show that the photoluminescence efficiency is strongly dependent on the degree of phase separation between the Si nanocrystals and the SiO2 matrix. This is likely connected with the Si/SiO2 interface characteristics, together with the features indicating the involvement of quantum confinement.  相似文献   

11.
Polycrystalline (1−x)Ta2O5xTiO2 thin films were formed on Si by metalorganic decomposition (MOD) and annealed at various temperatures. As-deposited films were in the amorphous state and were completely transformed to crystalline after annealing above 600 °C. During crystallization, a thin interfacial SiO2 layer was formed at the (1−x)Ta2O5xTiO2/Si interface. Thin films with 0.92Ta2O5–0.08TiO2 composition exhibited superior insulating properties. The measured dielectric constant and dissipation factor at 1 MHz were 9 and 0.015, respectively, for films annealed at 900 °C. The interface trap density was 2.5×1011 cm−2 eV−1, and flatband voltage was −0.38 V. A charge storage density of 22.8 fC/μm2 was obtained at an applied electric field of 3 MV/cm. The leakage current density was lower than 4×10−9 A/cm2 up to an applied electric field of 6 MV/cm.  相似文献   

12.
The step-terrace structures at the interface between the Si layer and the buried SiO2 layer of a Separation by IMplanted OXygen substrate has been observed by using atomic force microscopy (AFM) after removing the SiO2 and Si layers. The time evolution of the Si–SiO2 interface roughness during high-temperature annealing was analyzed by the scaling analysis of AFM data. The correlation length exhibited a nice correspondence to the size of square domain structures. Decreasing in the index of the length scale indicates that the growth mechanism changes as the annealing proceeds.  相似文献   

13.
In this paper we describe the formation of a luminescent (NH4)2SiF6 via porous silicon (PS) obtained from HNO3/HF vapour etching (VE) silicon (Si) substrates. It was found that at specific conditions, PS transforms in a luminescent thick white powder (WP) layer. Scanning electron microscopy (SEM) revealed that the WP has a coral-like structure. It was also found that PS persists as an intermediate layer between the Si substrate and the WP, and seems to be the seed that transforms into the WP. SEM microanalysis show that the WP is essentially composed of silicon (Si), nitrogen (N) and fluorine (F). Fourier transform infrared (FTIR) spectroscopy investigations show that this WP contains SiF62− and NH4+ ions and N---H chemical bonds. X-ray diffraction (XRD) patterns of the WP confirm that a (NH4)2SiF6 cubic phase is concerned. SEM microanalyses show an excess of Si in the WP matrix. FTIR spectroscopy and XRD analysis reveal the presence of crystalline Si particles and SiOx, both originating from the excess of Si. The (NH4)2SiF6 WP phase emits an intense photoluminescence (PL) band, shifted towards higher energies as compared to the starting PS layer. The possible origin and mechanism of the luminescence emission was discussed taking into account the ability of small SiOx-surrounded Si particles to emit PL at rather high energy. The wide range variation of the thickness of the (NH4)2SiF6 WP may be easily used for the grooving of Si wafers.  相似文献   

14.
A new method is presented to determine Si/SiO2 interface recombination parameters. The device employed is constituted by a polysilicon-oxide-semiconductor capacitor with a microscale central junction (a gate-controlled point-junction diode). The excess minority carriers are photo-generated rather than being injected, which results in a one-dimensional current flow normal to the Si/SiO2interface. The minority carrier quasi-Fermi level is probed at the Si/SiO2 interface by means of the point junction. The one-dimensionality of the current flow and the exact knowledge of the minority carrier quasi-Fermi level permit an accurate measurement of the recombination rate. The method has been applied to characterize p-type 100 Si/SiO2 interfaces with boron dopant concentrations ranging from 2.2×1015 to 2.0×1017 cm-3. Data analysis has been performed using a numerical scheme to find a quasi-exact solution for the current recombining at the interface. It was found that the interface recombination parameters (trap density and capture cross-sections) depend only weakly on trap energy in a wide range around midgap. The cross-section for capturing electrons (σn) was found to greatly exceed (by a factor of 102 to 103) the cross-section for capturing holes (σp).  相似文献   

15.
The generation of structural and electrical defects in Si/SiO2 structures upon high temperature annealing by the oxide decomposition reaction Si+SiO2→2SiO ↑ has been studied using scanning electron microscopy (SEM) and ramped current-voltage measurements. The SiO decomposition is nucleated at crystalline defects in the substrate and results in the formation of voids in the oxide. The voids grow laterally with annealing time, independent of the nature of the defect. Prior to the formation of physical voids in the oxide, defects become electrically active, leading to low field dielectric breakdown. The breakdown degradation is prevented when the O2 pressure in the annealing ambient is sufficient to reverse the decomposition reaction by reoxidizing the SiO product at the interface.  相似文献   

16.
We have shown that, for thermally evaporated Ta2O5 or ZrO2 thin films on Si(1 0 0), O2 annealing at 300–500 °C causes the formation of an interfacial silicon oxide layer as thin as 1–2 nm which can be interpreted in terms of their high permeability to oxygen. And we have demonstrated how useful the energy loss spectra of photoexcited electrons from core levels such as O 1s are to measure the energy bandgaps of very thin insulators. With the combination of measured bandgaps and valence band lineups determined for X-ray photoelectron spectroscopy valence band spectra, we have determined the energy band alignments of Ta2O5 and ZrO2 with Si(1 0 0) before and after the O2 annealing at 500 °C. In addition, we have demonstrated that total photoelectron yield spectroscopy provides us direct information to quantify the energy distributions of both the defect states in the high-k dielectrics and the dielectric/Si(1 0 0) interface states over nearly entire Si bandgap.  相似文献   

17.
In this work, the investigation of the interface state density and series resistance from capacitance–voltage (CV) and conductance–voltage (G/ωV) characteristics in In/SiO2/p-Si metal–insulator–semiconductor (MIS) structures with thin interfacial insulator layer have been reported. The thickness of SiO2 film obtained from the measurement of the oxide capacitance corrected for series resistance in the strong accumulation region is 220 Å. The forward and reverse bias CV and G/ωV characteristics of MIS structures have been studied at the frequency range 30 kHz–1 MHz at room temperature. The frequency dispersion in capacitance and conductance can be interpreted in terms of the series resistance (Rs) and interface state density (Dit) values. Both the series resistance Rs and density of interface states Dit are strongly frequency-dependent and decrease with increasing frequency. The distribution profile of RsV gives a peak at low frequencies in the depletion region and disappears with increasing frequency. Experimental results show that the interfacial polarization contributes to the improvement of the dielectric properties of In/SiO2/p-Si MIS structures. The interface state density value of In/SiO2/p-Si MIS diode calculated at strong accumulation region is 1.11×1012 eV−1 cm−2 at 1 MHz. It is found that the calculated value of Dit (≈1012 eV−1 cm−2) is not high enough to pin the Fermi level of the Si substrate disrupting the device operation.  相似文献   

18.
Atomic layer deposition of Cr2O3 thin films from CrO2Cl2 and CH3OH on amorphous SiO2 and crystalline Si(1 0 0) and -Al2O3() substrates was investigated, and properties of the films were ascertained. Self-limited growth with a rate of 0.05–0.1 nm/cycle was obtained at substrate temperatures of 330–420 °C. In this temperature range epitaxial eskolaite was formed on the -Al2O3() substrates. The predominant crystallographic orientation in the epitaxial films depended, however, on the growth temperature and film thickness. Sufficiently thick films grown on the SiO2 and Si(1 0 0) substrates contained also the eskolaite phase, but thinner films deposited at 330–375 °C on these substrates were amorphous. The growth rate data of films with different phase composition allowed a conclusion that the crystalline phase grew markedly faster than the amorphous phase did. The amorphous, polycrystalline and epitaxial films had densities of 4.9, 5.1 and 5.1–5.3 g/cm3, respectively.  相似文献   

19.
The evolution of the Si–SiO2 interface morphology of low-dose low-energy separation by implanted oxygen materials was investigated by transmission electron microscopy and atomic force microscopy. The Si–SiO2 interface morphology and the RMS roughness are strongly affected by the implantation conditions and the annealing process. Three main types of the domains including round, square, and pyramid shapes with the step-terrace structure were observed on the buried SiO2 surface. Round domains are observed in the early stage of the annealing process, while the square and pyramid domains are observed after the high temperature annealing. The mean RMS roughness decreases with increasing time and annealing temperature, while in the 1350 °C 4-h annealed samples, the mean RMS roughness decreases with either increasing the implantation dose or decreasing implantation energy. The scaling analysis shows that the Si–SiO2 interfaces were found to be self-affine on the short length scales with a roughness exponent above 0.50. Qualitative mechanisms of Si–SiO2 surface flattening are presented in terms of the variations of morphological features with the processing conditions.  相似文献   

20.
The surface morphology evolution of three thin polystyrene (PS)/polymethyl methacrylate (PMMA) blend films (<70 nm) on SiOx substrates upon annealing were investigated by atomic force microscopy (AFM) and some interesting phenomena were observed. All the spin-coated PS/PMMA blend films were not in thermodynamic equilibrium. For the 67.1 and the 27.2 nm PS/PMMA blend films, owing to the low mobility of the PMMA-rich phase layer at substrate surfaces and interfacial stabilization caused by long-range van der Waals forces of the substrates, the long-lived metastable surface morphologies (the foam-like and the bicontinuous morphologies) were first observed. For the two-dimensional ultrathin PS/PMMA blend film (16.3 nm), the discrete domains of the PS-rich phases upon the PMMA-rich phase layer formed and the secondary phase separation occurred after a longer annealing time.  相似文献   

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