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1.
《Current Applied Physics》2015,15(3):279-284
A non-volatile flash memory device based on metal oxide semiconductor (MOS) capacitor structure has been fabricated using platinum nano-crystals(Pt–NCs) as storage units embedded in HfAlOx high-k tunneling layers. Its memory characteristics and tunneling mechanism are characterized by capacitance–voltage(C–V) and flat-band voltage-time(ΔVFB-T) measurements. A 6.5 V flat-band voltage (memory window) corresponding to the stored charge density of 2.29 × 1013 cm−2 and about 88% stored electron reserved after apply ±8 V program or erase voltage for 105 s at high frequency of 1 MHz was demonstrated. Investigation of leakage current–voltage(J–V) indicated that defects-enhanced Pool-Frenkel tunneling plays an important role in the tunneling mechanism for the storage charges. Hence, the Pt–NCs and HfAlOx based MOS structure has a promising application in non-volatile flash memory devices.  相似文献   

2.
《Current Applied Physics》2018,18(1):107-113
In c-Si solar cells, surface recombination velocity increases as the wafer thickness decreases due to an increase in surface to volume ratio. For high efficiency, in addition to low surface recombination velocity at the rear side, a high internal reflection from the rear surface is also required. The SiOxNy film with low absorbance can act as rear surface reflector. In this study, industrially feasible SiO2/SiOxNy stack for rear surface passivation and screen printed local aluminium back surface field were used in the cell structure. A 3 nm thick oxide layer has resulted in low fixed oxide charge density of 1.58 × 1011 cm−2 without parasitic shunting. The oxide layer capped with SiOxNy layer led to surface recombination velocity of 155 cm/s after firing. Using single layer (SiO2) rear passivation, an efficiency of 18.13% has been obtained with Voc of 625 mV, Jsc of 36.4 mA/cm2 and fill factor of 78.7%. By using double layer (SiO2/SiOxNy stack) passivation at the rear side, an efficiency of 18.59% has been achieved with Voc of 632 mV, Jsc of 37.6 mA/cm2, and fill factor of 78.3%. An improved cell performance was obtained with SiO2/SiOxNy rear stack passivation and local BSF.  相似文献   

3.
We have fabricated indium–gallium–zinc (IGZO) thin film transistor (TFT) using SiOx interlayer modified aluminum oxide (AlOx) film as the gate insulator and investigated their electrical characteristics and bias voltage stress. Compared with IGZO-TFT with AlOx insulator, IGZO-TFT with AlOx/SiOx insulator shows superior performance and better bias stability. The saturation mobility increases from 5.6 cm2/V s to 7.8 cm2/V s, the threshold voltage downshifts from 9.5 V to 3.3 V, and the contact resistance reduces from 132 Ωcm to 91 Ωcm. The performance improvement is attributed to the following reasons: (1) the introduction of SiOx interlayer improves the insulator surface properties and leads to the high quality IGZO film and low trap density of IGZO/insulator interface. (2) The better interface between the channel and S/D electrodes is favorable to reduce the contact resistance of IGZO-TFT.  相似文献   

4.
We introduce a room temperature and solution-processible vanadium oxide (VOx) buffer layer beneath Au source/drain electrodes for bottom-contact (BC) organic field-effect transistors (OFETs). The OFETs with the VOx buffer layer exhibited higher mobility and lower threshold voltages than the devices without a buffer layer. The hole mobility with VOx was over 0.11 cm2/V with the BC geometry with a short channel length (10 μm), even without a surface treatment on SiO2. The channel width normalized contact resistance was decreased from 98 kΩ cm to 23 kΩ cm with VOx. The improved mobility and the reduced contact resistance were attributed to the enhanced continuity of pentacene grains, and the increased work function and adhesion of the Au electrodes using the VOx buffer layer.  相似文献   

5.
In this investigation the composite SiOx〈Ti〉 films were prepared by the thermal evaporation of a mixture of silicon oxide (SiO2) and Тi powders. The optical transmission of the films in the IR spectral range and their temperature-sensitive properties are studied. By varying the contents of the metal in vaporizer and time of evaporation it is possible to obtain SiOx〈Ti〉 layers with resistance (for monopixel of 0.8 × 1 mm) from tens kOhms to MOhms and a value of the temperature coefficient of resistance (TCR) is equal to −2.22% K−1. IR spectrum of SiOx〈Ti〉 film is characterized by a broad absorption band in the range of 8–12 μm which is associated with the Si–O–Si stretching mode.Investigations of the effect of gamma irradiation on SiOx〈Ti〉 films have shown that their temperature-sensitive properties, in particular TCR does not change up to a dose of 106 Gy.These results suggest that SiOx〈Ti〉 films can be used as materials for production of radiation-resistant thermosensitive detectors operated in radiation fields of γ-radiation and combining functions of IR-absorption and formation of an electric signal.  相似文献   

6.
A theoretical model is proposed on how a Si dangling bond associated with an oxygen vacancy on a SiO2 surface (Es′ center) should be observed by Auger electron spectroscopy (AES). The Auger electron distribution NA(E) for the L23VV transition band is calculated for a stoichiometric SiO2 surface, and for a SiOx surface containing Si-(e?O3) coordinations. The latter is characterized by an additional L23VD transition band, where D is the energy level of the unpaired electron e?. The theoretical NA(E) spectra are compared with experimental N(E) spectra for a pristine, and for an electron radiation damaged quartz surface. Agreement with the theoretical model is obtained if D is assumed to lie ≈2 eV below the conduction band edge. This result shows that AES is uniquely useful in revealing the absolute energy level of localized, occupied surface defect states. As the L23VD transition band (main peak at 86 eV) cannot unambiguously be distinguished from a SiSi4 coordination L23VV spectrum (main peak at 88 eV), supporting evidence is presented as to why we exclude a SiSi4 coordination for our particular experimental example. Application of the Si-(e?O3) model to the interpretation of SiO2Si interface Auger spectra is also discussed.  相似文献   

7.
《Current Applied Physics》2020,20(12):1386-1390
The use of SiO2/4H–SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) can be problematic due to high interface state density (Dit) and low field-effect mobility (μfe). Here, we present a tetra-ethyl-ortho-silicate (TEOS)-based low-pressure chemical vapor deposition (LPCVD) method for fabricating the gate oxide of 4H–SiC MOSFETs using nitric oxide post-deposition annealing. SiO2/4H–SiC MOS capacitors and MOSFETs were fabricated using conventional wet and TEOS oxides. The measured effective oxide charge density (Qeff) and Dit of the TEOS-based LPCVD SiO2/4H–SiC MOS capacitor with nitridation were 4.27 × 1011 cm−2 and 2.99 × 1011 cm−2eV−1, respectively. We propose that the oxide breakdown field and barrier height were dependent on the effective Qeff. The measured μfe values of the SiO2/4H–SiC MOSFETs with wet and TEOS oxides after nitridation were, respectively, 11.0 and 17.8 cm2/V due to the stable nitrided interface between SiO2 and 4H–SiC. The proposed gate stack is suitable for 4H–SiC power MOSFETs.  相似文献   

8.
The nucleation, growth, and morphology of gold (Au) clusters on an irreducible oxide (SiO2), highly reduced TiOx (x ∼ 1), and less reduced TiOx (x ∼ 2) were investigated by scanning tunneling microscopy (STM) with the goal of understanding the relationship between the nucleation, growth, and morphology of Au clusters and the reducibility of the oxide support. Au clusters show preferential nucleation and growth on a TiOx surface compared to a SiO2 surface. In addition, higher densities of Au clusters were found on highly reduced TiOx, suggesting that reduced Ti sites play a role as an active site for the nucleation and growth of Au clusters.  相似文献   

9.
The junction properties of tunnel silicon oxide (SiOx) passivated contact (TOPCon) with n-type poly-Si on p-type c-Si wafer are characterized using current-voltage (J-V) and capacitance-voltage (C-V) measurements. The dark J-V curves show a standard diode characteristic with a turn-on voltage of ~0.63 V, indicating a p-n junction is formed. While the C-V curve displays an irregular shape with features of 1) a slow C increase with the decrease of the magnitude of reverse bias voltage, being used to estimate the built-in potential (Vbi), 2) a significant increase at a given positive bias voltage, corresponding to the geometric capacitance crossing the ultrathin SiOx, and 3) a sharp decrease to negative values, resulting from the charge tunneling through the SiOx layer. The C of depleting layer deviates from the normal linear curve in the 1/C2-V plot, which is caused by the diffusion of P dopants from the n-type poly-Si into the p-type c-Si wafer as confirmed by the electrochemical capacitance-voltage measurements. However, the 1/C2+γ-V plots with γ > 0 leads to linear curves with a proper γ and the Vbi can still be estimated. We find that the Vbi is the range of 0.75–0.85 V, increases with the increase of the doping ratio during the poly-Si fabrication process, and correlates with the passivation quality as measured by the reverse saturated current and implied open circuit voltage extracted from transient photoconductivity decay.  相似文献   

10.
The low-temperature electrical and magnetotransport characteristics of partially relaxed Si/Si1−xGex heterostructures with two-dimensional electron channel (ne≥1012 cm−2) in an elastically strained silicon layer of nanometer thickness have been studied. The detailed calculation of the potential and of the electrons distribution in layers of the structure was carried out to understand the observed phenomena. The dependence of the tunneling transparency of the barrier separating the 2D and 3D transport channels in the structure, was studied as a function of the doping level, the degree of blurring boundaries, layer thickness, degree of relaxation of elastic stresses in the layers of the structure. Tunnel characteristics of the barrier between the layers were manifested by the appearance of a tunneling component in the current–voltage characteristics of real structures. Instabilities, manifested during the magnetotransport measurements using both weak and strong magnetic fields are explained by the transitions of charge carriers from the two-dimensional into three-dimensional state, due to interlayer tunneling transitions of electrons.  相似文献   

11.
This paper reports on the results of investigations into the spectral dependences of thermally stimulated luminescence and the temperature dependences of tunneling luminescence in highly oxidized porous silicon samples. Two new mechanisms of localization of charge carriers are considered in terms of the specific features revealed in the spectral dependences of the thermally stimulated luminescence and nonmonotonic temperature dependences of the Becquerel index of tunneling luminescence decay. The proposed mechanisms of charge carrier localization are associated with structure heterogeneities inherent in these objects, namely, superficial SiOx oxide shells (0<x≤2) enclosing silicon particles and an undulating structure of silicon wires.  相似文献   

12.
(9−x)CaO·xMgO·15Na2O·60SiO2·16CaF2(x=0, 2, 4, 6, and 9) oxyfluoride glasses were prepared. Utilizing the Raman scattering technique together with 29Si and 19F MAS NMR, the effect of alkaline metal oxides on the Q species of glass was characterized. Raman results show that as magnesia is added at the expense of calcium oxide, the disproportional reaction Q3→Q4+Q2 (Qn is a SiO4 tetrahedron with n bridging oxygens) prompted due to the high ionic field strength of magnesia, magnesium oxide entered into the silicate network as tetrahedral MgO4, and removed other modifying ions for charge compensation. This reaction was confirmed by 29Si MAS NMR. 19F MAS NMR results show that fluorine exists in the form of mixed calcium sodium fluoride species in all glasses and no Si–F bonds were formed. As CaO is gradually replaced by MgO (x=6, 9), a proportion of the magnesium ions combines with fluorine to form the MgF+ species. Meanwhile, some part of Na+ ions complex F in the form of F–Na(6).  相似文献   

13.
《Current Applied Physics》2014,14(3):232-236
The characteristics of hybrid gadolinium oxide nanocrystal (Gd2O3-NC) and gadolinium oxide charge trapping (Gd2O3-CT) memories were investigated with different Gd2O3 film thickness. By performing the rapid thermal annealing on Gd2O3 films with different thickness, the Gd2O3-NCs with the diameter of 6–9 nm for charge storage, surrounded by the amorphous Gd2O3 (α-Gd2O3) layer, were formed. The α-Gd2O3 layer was considered to be the charge trapping layer, resulting in the large memory window of Gd2O3-NC/CT memories with thick Gd2O3 film. The charge trapping energy level of the Gd2O3-NCs and α-Gd2O3 layer was extracted to be 0.16 and 0.45 eV respectively by using the temperature-dependent retention measurement. Further, after a 106 program/erase cycling operation, the memory with thin Gd2O3 film can be predicted to sustain a 94% memory window of the first cycling one while the memory with thick Gd2O3 film suffered from a 30% charge loss because of the traps within the α-Gd2O3 layer. The Gd2O3 film thickness of 10 nm was optimized to exhibit superior performances of the Gd2O3-NC/CT memory, which can be applied into the nonvolatile memory.  相似文献   

14.
Recent interests in mixed metal oxide nanostructured materials especially IrxRu1−xO2 compounds have been mainly driven by the technological application as electrocatalyst and electrode materials. We present room temperature Raman scattering results of single crystalline IrxRu1−xO2 (0 ≤ x ≤ 1) nanowires grown by atmospheric pressure chemical vapor deposition. We observed that the Eg, the A1g, and the B2g phonon modes of a single IrxRu1−xO2 nanowire are blue-shifted linearly with respect to the Ir contents from which we could get stoichiometry information. We also observed that the asymmetric lineshape and the broadening of the full width at half maximum of the Eg mode that involves the out-of-plane oxygen vibration. The unusual asymmetric broadening of the Eg phonon can be explained by the activation of the non-zone-center phonons due to substitutional disorder present in the system. We also found that there is a mixed mode of the A1g and the B2g phonons due to the substitutional disorder, in the range of 630–750 cm−1.  相似文献   

15.
In this paper, effect of Eu3+ doping concentrations on microstructure and photoluminescence of Sr2SiO4 phosphors was investigated. The Sr2?xSiO4:xEu3+ phosphors with x=0.05, 0.1, 0.2, 0.3 were synthesized by microwave assisted sintering at 1200 °C for 60 min in air. X-ray powder diffraction analysis confirmed the formation of pure Sr2SiO4 phase without second phase or phases of starting materials irrespective of the adding amount of Eu3+. From scanning electron microscopy image, it is found that with more Eu3+ ions introduced to Sr2SiO4, the shape of the particles is not much different from each other, but the particle size decreases significantly from 1 to 2 μm (when x=0.05) to less than 500 nm (when x=0.3). The emission spectrum was located obviously at 617 nm as the excitation spectrum at λex=395 nm, and it had best emission intensity when x=0.1.  相似文献   

16.
C–V characteristics and leakage currents of metal-insulator-silicon structures containing insulating film composed of thermally grown Ta2O5 and ultrathin SiOxNy layer grown in N2O plasma were studied. Leakage in the structures is explained by tunneling in SiOxNy layer and Poole–Frenkel internal field assisted emission in Ta2O5. Theoretical calculations were made by known theoretical expression, while using fitted values of the thickness of SiOxNy, defect related constants for Ta2O5, and compensation degree r=1 for Ta2O5. For positive gate biases, tunneling of electrons from the silicon conduction band through SiO2 is considered, while for gates negatively biased, tunneling of holes from the silicon valence band. In the early stage of nitridation barriers for injection decreases rapidly, then much slower. The thickness of the SiOxNy layer increases slowly with the nitridation time, as a result of the created barrier against diffusion of silicon atoms created by nitrogen incorporated at the interface between the silicon and oxide SiOxNy layer. PACS 73.40.Qv; 73.50.-h; 73.61.-r An erratum to this article can be found at .  相似文献   

17.
The kinetics of electron and hole accumulation in metal-oxide-nitride-oxide-semiconductor structures is studied. Experimental data are compared with a theoretical model that takes into account tunnel injection, electron and hole capture by traps in amorphous silicon nitride SiNx, and trap ionization. Agreement between experimental and calculated data is obtained for the bandgap width E g = 8.0 eV of amorphous SiO2, which corresponds to the barrier for holes Φh = 3.8 eV at the Si/SiO2 interface. The tunneling effective masses for holes in SiO2 and SiNx are estimated at m h * ≈ (0.4–0.5)m 0. The parameters of electron and hole traps in SiNx are determined within the phonon-coupled trap model: the optical energy W opt = 2.6 eV and the thermal energy W T = 1.3 eV.  相似文献   

18.
The impact of hydrogen desorption on the electrical properties of TiOx on crystalline silicon (c-Si) with SiOy interlayers is studied for the development of high-performance TiOx carrier-selective contacts. Compared with the TiOx/c-Si heterocontacts, a lower surface recombination velocity of 9.6 cm/s and lower contact resistivity of 7.1 mΩ cm2 are obtained by using SiOy interlayers formed by mixture (often called SC2). The hydrogen desorption peaks arising from silicon dihydride (α1) and silicon monohydride (α2) on the c-Si surface of the as-deposited samples are observed. The α1 peak pressure of as-deposited heterocontacts with SiOx interlayers is lower than that of heterocontacts without a SiOy interlayer. Furthermore, the hydrogen desorption energies are found to be 1.76 and 2.13 eV for the TiOx/c-Si and TiOx/SC2-SiOy/c-Si heterocontacts, respectively. Therefore, the excellent passivation of the TiOx/SC2-SiOy/c-Si heterocontacts is ascribed to the relatively high rupture energy of bonding between Si and H atoms.  相似文献   

19.
This Letter demonstrates improved passivating contacts for silicon solar cells consisting of doped silicon films together with tunnelling dielectric layers. An improvement is demonstrated by replacing the commonly used silicon oxide interfacial layer with a silicon nitride/silicon oxide double interfacial layer. The paper describes the optimization of such contacts, including doping of a PECVD intrinsic a‐Si:H film by means of a thermal POCl3 diffusion process and an exploration of the effect of the refractive index of the SiNx. The n+ silicon passivating contact with SiNx /SiOx double layer achieves a better result than a single SiNx or SiOx layer, giving a recombination current parameter of ~7 fA/cm2 and a contact resistivity of ~0.005 Ω cm2, respectively. These self‐passivating electron‐selective contacts open the way to high efficiency silicon solar cells. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)  相似文献   

20.
Germanium quantum dots (QDs) were extracted from ultrathin SixGe1−x oxide films using scanning tunneling microscope (STM) tips. The extraction was most efficiently performed at a positive sample bias voltage of +5.0 V. The tunneling current dependence of the extraction efficiency was explained by the electric field evaporation transfer mechanism for positive Ge ions from QDs to STM tips. Ge QDs (∼7 nm) were formed and isolated spatially by extracting the surrounding Ge QDs with an ultrahigh density of >1012 cm−2. Scanning tunneling spectroscopy of the spatially-isolated QDs revealed that QDs with an ultrahigh density are electrically-isolated from the adjacent dots.  相似文献   

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