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《Superlattices and Microstructures》1998,23(5):991-997
The induced defects and their distribution in a-Si:H/a-SiNx:H multilayers are determined using an electromagnetic technique (EMT) and positron annihilation technique (PAT). It is found that the distributions of the induced defects in the interface regions on both sides of the a-Si:H sublayer are asymmetric and related to the growth direction of the film; a large number of induced defects are found only in the interface region away from the substrate. 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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The strained Si0.8Ge0.2 film has been prepared onto Si substrate by using an ultrahigh-vacuum chemical vapor deposition system. A low cost wavelength filter of photodetector has been demonstrated for the first time. This filter was simply carried out by just inserting a 60 nm thick a-Si:H capped layer onto Si0.8Ge0.2 thin film. The room-temperature photoluminescence shows that the sample with Si0.8Ge0.2 layer has a tendency to shift wavelength into longer regime than that of Si substrate. The full width at half maximum (FWHM) was 185 nm for Si0.8Ge0.2 photodetector without a-Si:H capped. By inserting a 60 nm thick a-Si:H capped layer, the FWHM was narrowed into 97 nm. This demonstrates that the a-Si:H capped layer has an ability acted as wavelength filter in our study. 相似文献
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利用等离子体增强化学气相沉积技术制备了a-Si ∶H/SiO2多量子阱结构材料.对a-Si ∶H/SiO2多量子阱样品分别进行了3种不同的热处理,其中样品经1100 ℃高温退火可获得尺寸可控的nc-Si:H/SiO2量子点超晶格结构,其尺寸与非晶硅子层厚度相当.比较了a-Si ∶H/SiO2多量子阱材料与相同制备工艺条件下a-Si ∶H材料的吸收系数,在紫外/可见短波段前者的吸收系数明显增大,光学吸收边蓝移,说明该材料
关键词:
多量子阱
量子限制效应
光学吸收
能带结构 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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《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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The influence of atomic hydrogen annealing on the optical parameters of a-Si:H films was studied using spectrophotometric measurements of the film transmittance and reflectance in the wavelength range 200-3000 nm. In this annealing, the deposition of a thin layer and treatment with atomic hydrogen were repeated alternately, where the thickness of the thin cyclic layer, dcyc, and the treatment time of each cycle, tca, were kept fixed for each sample. A series of different samples with average thickness of 0.5 μm and different dcyc and tca were prepared. It was found that the refractive index, n, and the optical energy gap, Eg, increase as the treatment time, tca, increases from 0 to 60 s, while at tca=120 s both n and Eg decrease. Also, both the refractive index and the optical energy gap decrease with increasing the relative diffusion length of hydrogen, √tca/dcyc from 0.39 to 0.77. The widening of Eg is due to the structural relaxation resulting from impingement of atomic hydrogen on the growing surface. Thus, a good-quality a-Si:H with Urbach parameter 65 mev and optical energy gap of 1.78 eV was successfully prepared. 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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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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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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In this study the electron diffusion length L
n is determined from the relative spectral response of the photocurrent characteristics of the p/i/n sandwich structure ITO/a-SiC:H(p-type)/a-Si:H/a-Si:H(n-type)/Pd. The techniques used for the preparation of the a-Sic:H and a-Si:H amorphous films were glow-discharge and rf magnetron sputtering, respectively. The thickness of the p-type, intrinsic and n-type layer were 400 Å, 7000 Å and 600 Å, respectively. The response of the short-circuit current density J
sc was measured versus the photon energy hv at both constant light intensity and constant temperature. The electron diffusion length was found to be 0.31 m by means of the method of Agarwala and Tewary. Although, in the case of single crystals many diffusion length measurements have been made, there are only few papers for amorphous silicon this films [1]. As it is well-known, the diffusion length of the charge carriers is the most important parameter from the point of view of solar cell applications [2]. In order to obtain a high efficiency in a solar cell all carriers created under illumination in the intrinsic layer should reach the electrodes [3]. In the case that the thickness of the intrinsic layer is much larger than the diffusion length, not all carriers can reach the electrodes and, accordingly, a low efficiency results [4]. On the other hand, carriers which reach the electrodes without thermalizing do not contribute to the photocurrent and finally the efficiency of the solar cell is negatively affected. In order to avoid such an effect to a large extent, the thickness of the amorphous layers in a p/i/n solar cell must be conveniently chosen compared to the diffusion length of the carriers.Here it is aimed to determine the electron diffusion length. In order to achieve this goal, the photocurrent characteristics of an ITO/a-SiC:H(p-type)/a-Si:H/a-Si:H(n-type)/Pd structure was measured versus the photon energy at constant light intensity and constant temperature. In order to determine the electron diffusion length, the method of Agarwala and Tewary [5] was utilized. 相似文献