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Effects of hydrogen plasma annealing on the luminescence from a-Si:H/SiO2 and nc-Si/SiO2 multilayers
Effects of post-hydrogen plasma annealing (HPA) on a-Si:H/SiO2 and nc-Si/SiO2 multilayers have been investigated and compared. It is found that photoluminescence (PL) from hydrogen-passivated samples was improved due to the reduction of non-radiative recombination defects. Some interesting difference is that during HPA, atomic hydrogen can directly passivate defects of a-Si:H/SiO2, which results in the reappearance of luminescence band at 760 nm, while for nc-Si/SiO2, hydrogen passivation requires additional thermal annealing after nc-Si/SiO2 multilayer was treated by HPA. It is indicated that higher atomic mobility is needed to passivate defects at nc-Si/SiO2 interface compared with a-Si:H/SiO2 interface. 相似文献
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本文从a-Si:H体材料的缺陷态模型出发,考虑在a-Si:H/a-SiNx:H超晶格中由于空间电荷转移掺杂效应,以及界面不对称引起的a-Si:H阱层的能带下降和弯曲,严格求解空间电势分布和电荷分布,发现a-Si:H阱层中能带的下降值远大于由界面电荷不对称所引起的两端电势能差,且随转移到阱层中的电荷总量的变化非常敏感。空间电荷分布比较平缓,当不对称参数K=0.9时,空间电荷浓度的最大差值不到两倍。在此基础上,计算了超晶格中光电导的温度曲线,发现引起超晶格中暗电导和光电导相对于单层膜增大的主要原因是转移电荷量的多少,而界面电荷不对称的影响则小得多。计算中对带尾态采用Simmons-Taylor理论,考虑a-Si:H中悬挂键的相关性,并用巨正则分布讨论其在复合过程中的行为。
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《Superlattices and Microstructures》1995,17(1):1-4
Surface Rayleigh acoustic waves and related elastic properties of quasiperiodic and periodic modulated a-Si:H/a-SiNx:H superlattices have been studied by means of a light-scattering technique. Changes in the phase velocity of the surface Rayleigh acoustic waves as a function of sublayer (a-Si:H) thickness are interpreted using an effective medium model. Despite the existence of structural mismatch in the bond-length and coordination number and of structural disorder in the bond-angle for Si-N and Si-Si, no appreciable discrepancy between the measured results and the theoretical predictions has been found. 相似文献
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A. A. Onischuk R. I. Samoilova V. P. Strunin E. N. Chesnokov R. N. Musin V. S. Bashurova A. G. Maryasov V. N. Panfilov 《Applied magnetic resonance》1998,15(1):59-94
The dangling bond defects were investigated in a-Si:H particles formed under silane thermal decomposition in flow reactor. EPR together with hydrogen evolution method were used. The experimental results allowed us to conclude that there are two kinds of dangling bond defects in a-Si:H aerosol particles. The defects of the first kind are localized on the surface of interconnected microvoids and microchannels (surface dangling bonds) and those of the second kind are embedded in amorphous silicon network (volume dangling bonds). The thermal equilibration of dangling bonds and temperature dependence of equilibrium dangling bond concentration were investigated. It was found that at temperatures > 400 K the dangling bond concentrationNApplied Magnetic Resonance s reversibly depends on sample temperature. The volume dangling bond concentration increases with temperature increasing (the effective activation energy of dangling bond formationU > 0), and the surface dangling bond concentration decreases with temperature increasing (U < 0). It has been found that EPR line is considerably asymmetric for samples with high hydrogen content and for low hydrogen content the EPR line is weakly asymmetric. A conclusion was drawn that the asymmetry degree depends on amorphous silicon lattice distortions. This conclusion has been confirmed by EPR spectra simulations. 相似文献
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Amorphous silicon-nitride thin films a-Si:N:H were obtained by plasma enhanced chemical vapour deposition (PECVD) method from
SiH4+NH3 at 13.56 MHz. The process parameters were chosen to obtain the films of properties suitable for optoelectronic and mechanical
applications. FTIR analysis of a-Si:N:H films indicated the presence of numerous hydrogen bonds (Si-H and N-H) which passivate
structural defects in multicrystalline silicon and react with impurities. The morpho-logical investigations show that the
films are homogeneous. The deposition of a-Si:N:H layers leads to the decrease in friction coefficient of used substrates.
Optical properties were optimised to obtain the films of low effective reflectivity, large energy gap Eg from 2.4 to 2.9 eV and refractive index in the range of 1.9 to 2.2. Reduction of friction coefficient for monocrystalline
silicon after covering with a-Si:N:H films was observed: from 0.25 to 0.18 for 500 cycles. 相似文献
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《Superlattices and Microstructures》2000,28(3):207-215
The structural properties of superlattices composed by hydrogenated amorphous silicon/silicon carbide (a-Si:H/a- Si1 − xCx:H) and silicon/germanium (a-Si:H/a-Ge:H), deposited by the plasma-enhanced chemical vapor deposition (PECVD) technique, were analyzed by means of small-angle X-ray diffraction. The relevant structural parameters, such as the multilayer period, the individual layer thickness, the width of the interface and the optical constants, were determined by modeling the experimental reflectivity. The model was based on the dynamical diffraction theory, including material mixing at the interface, interface roughness and random variation of component thickness. In addition, the effect of the direct beam and background on the measured intensities were considered. 相似文献
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L. Wang X. Huang Z. Ma Z. Li J. Shi L. Zhang Y. Bao X. Wang W. Li J. Xu K. Chen 《Applied Physics A: Materials Science & Processing》2002,74(6):783-786
The crystallinity of Si/SiNx multilayers annealed by a rapid thermal process and furnace annealing is investigated by a Raman-scattering technique and
transmission electron microscopy. It is found that the crystallization temperature varies from 900 °C to 1000 °C when the
thickness of a-Si:H decreases from 4.0 nm to 2.0 nm. Raman measurements imply that the high crystallization temperature for
the a-Si:H sublayers originates from the confinement modulated by the interfaces between a-Si:H and a-SiNx:H. In addition to the annealing temperature, the thermal process also plays an important role in crystallization of a-Si
sublayers. The a-Si:H sublayers thinner than 4.0 nm can not be crystallized by furnace annealing for 30 min, even when the
annealing temperature is as high as 1000 °C. In contrast, rapid thermal annealing is advantageous for nucleation and crystallization.
The origin of process-dependent crystallization in constrained a-Si:H is briefly discussed.
Received: 11 April 2001 / Accepted: 20 June 2001 / Published online: 30 August 2001 相似文献
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Tian Chen Chao Ye Yanhong Deng Ying Yuan Shuibin Ge Yijun Xu Zhaoyuan Ning Xiaopin Pan Zhenmin Wang 《Journal of luminescence》2012,132(9):2416-2420
Amorphous Si:C:O:H films were fabricated at low temperature by C2F6 and O2/C2F6 plasma treating silicone oil liquid. The a-Si:C:O:H films fabricated by C2F6 plasma treatment exhibited white photoluminescence at room temperature, while that by O2/C2F6 plasma treatment exhibited blue photoluminescence. Fourier transformed infrared spectroscopy and Raman spectroscopy studies showed that the sp3 and sp2 hybridized carbons, SiC bond, SiO bond and carbon-related defects in a-Si:C:O:H films correlated with photoluminescence. It is suggested that the blue emission at 469 nm was related to the sp3 and sp2 hybridized carbons, SiC bond, carbon dangling bonds as well as SiO short chains and small clusters, while the light emitting at 554 nm was related to the carbon-related defects. 相似文献
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Jeong Chul Lee Viresh Dutta Jinsu Yoo Junsin Yi Jinsoo Song Kyung Hoon Yoon 《Superlattices and Microstructures》2007,42(1-6):369
Superstrate p-i-n amorphous silicon thin-film (a-Si:H) solar cells are prepared on SnO2:F and ZnO:Al transparent conducting oxides (TCOs) in order to see the effect of TCO/p-layers on a-Si:H solar cell operation. The solar cells prepared on textured ZnO:Al have higher open circuit voltage Voc than cells prepared on SnO2:F. The presence of a thin microcrystalline p-type silicon layer (μc-Si:H) between ZnO:Al and p a-SiC:H plays a major role by causing an improvement in the fill factor as well as in Voc of a-Si:H solar cells prepared on ZnO:Al TCO. Without any treatment of the p-i interface, we could obtain a high Voc of 994 mV while keeping the fill factor (72.7%) and short circuit current density Jsc at the same level as for the cells on SnO2:F TCO. This high Voc value can be attributed to modification in the current transport in this region due to creation of a potential barrier. 相似文献
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Emil Pin?ík Hikaru Kobayashi Rudolf Hajossy Masao Takahashi Matej Jergel Luc Ortega Martin Krá? 《Applied Surface Science》2007,253(16):6697-6715
Amorphous hydrogenated silicon (a-Si:H) belongs still to most promising types of semiconductors for its utilization in fabrication of TFTs and thin film solar cell technology due to corresponding cheap a-Si:H-based device production in comparison with, e.g. crystalline silicon (c-Si) technologies. The contribution deals with both two important modes of preparation of very-thin and ultra-thin silicon dioxide films in the surface region of a-Si:H semiconductor (oxygen plasma sources and liquid chemical methods) and electrical, optical and structural properties of produced oxide/semiconductor structures, respectively. Dominant aim is focused on investigation of oxide/semiconductor interface properties and their comparison and evaluation from view of utilization of used technological modes in the nanotechnological industry. Following three basic types of oxygen plasma sources were used for the first time in our laboratories for treatments of surfaces of a-Si:H substrates: (i) inductively coupled plasma in connection with its applying at plasma anodic oxidation; (ii) rf plasma as the source of positive oxygen ions for plasma immersion ion implantation process; (iii) dielectric barrier discharge ignited at high pressures.The liquid chemical manner of formation SiO2/a-Si:H structures uses 68 wt% nitric acid aqueous solutions (i.e., azeotropic mixture with water). Their application in crystalline Si technologies has been presented with excellent results in the formation of ultra-thin SiO2/c-Si structures [H. Kobayashi, M. Asuha, H.I. Takahashi, J. Appl. Phys. 94 (2003) 7328].Passivation of surface and interface states by liquid cyanide treatment is additional original technique applied after (or before) formation of almost all formed thin film/a-Si:H structures. Passivation process should be used if high-quality electronical parameters of devices can be reached. 相似文献
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H. Tanaka T. Sakai M. Shimbo S. Arai T. Yamazaki 《Applied Physics A: Materials Science & Processing》1986,41(4):311-314
One of the disadvantages of applying an a-Si:H thin-film transistor (TFT) to an active matrix-addressed liquid crystal (LC) panel is that a TFT with an a-Si:H has a very large photo-leakage current because of the high photo-conductivity of an a-Si:H itself.We have tried decreasing the photo-leakage current by varying the thickness of an a-Si:H layer (L) in TFTs and investigated the characteristics of TFTs, mainly drain voltage versus drain current containing photo-leakage current (I
ph).As a result, it is shown that lnI
ph is proportional to InL, and its gradient is 1.5–2.0. We assume that the thinner an a-Si:H layer is, the more effective the recombination of carriers at the interface states is forI
ph.We have applied TFT with a very thin a-Si:H layer (30nm) to a full-color active matrix-addressed LC panel for a moving picture display and realized a display of good quality under illuminated condition of 5×104lx without a shading layer in it. 相似文献
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We report a determination of the density of singly-occupied dangling bonds at the a-Si:H/a-SiNx:H interface obtained from ESR measurements of superlattice structures. The surprisingly low result of 1.3 × 1010 cm?2 calls for a reexamination of previous transport and optical measurements. The ESR data do not preclude a high interface density of charged dangling bonds. 相似文献
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Young-Woo Ok Min-Gu Kang Donghwan Kim Jeong Chul Lee Kyung Hoon Yoon 《Current Applied Physics》2009,9(6):1186-1190
We fabricated point-contacted a-Si:H(p)/c-Si(n) heterojunction solar cells using patterned SiO2 and investigated their electrical properties using the light current–voltage (I–V) curve and Suns-Voc measurements. The light I–V curves showed bias-dependent changes according to the applied voltage in the point-contacted cells, especially in the samples with a long distance between the point-contacted junctions. The Suns-Voc measurements showed that the bias-dependence of the light I–V curves did not originate from the recombination in the SiO2/Si or a-Si:H(p)/c-Si(n) interface, but from the series resistances. It is possible to explain the bias-dependent light I–V curve in terms of the conductivity of a-Si:H(p) and difference in the electrical contact properties between a-Si:H(p), ZnO and c-Si(n). These results mean that the electrical properties of the a-Si:H(p) layer and the contact properties with this layer are also critical to obtain a high Jsc and fill factor in n-type based Si heterojunction solar cells. 相似文献
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Katarína Gmucová Martin Weis Ignác Capek Lívia Chitu Eva Majková 《Applied Surface Science》2008,254(21):7008-7013
Langmuir-Blodgett technique has been used for the deposition of ordered two-dimensional arrays of iron oxides (Fe3O4/Fe2O3) nanoparticles onto the photovoltaic hydrogenated amorphous silicon (a-Si:H) thin film. Electric field at the a-Si:H/iron oxides nanoparticles interface was directly in the electrochemical cell modified by light soaking and bias voltage (negative or positive) pretreatment resulting in the change of the dominant type of charged deep states in the a-Si:H layer. Induced reversible changes in the nanoparticle redox behavior have been observed. We suggest two possible explanations of the data obtained, both of them are needed to describe measured electrochemical signals. The first one consists in the electrocatalytical effect caused by the defect states (negatively or positively charged) in the a-Si:H layer. The second one consists in the possibility to manipulate the nanoparticle cores in the prepared structure immersed in aqueous solution via the laser irradiation under specific bias voltage. In this case, the nanoparticle cores are assumed to be covered with surface clusters of heterovalent complexes created onto the surface regions with prevailing ferrous or ferric valency. Immersed in the high viscosity surrounding composed of the wet organic nanoparticle envelope these cores are able to perform a field-assisted pivotal motion. The local electric field induced by the deep states in the a-Si:H layer stabilizes their “orientation ordering” in an energetically favourable position. 相似文献