共查询到16条相似文献,搜索用时 250 毫秒
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本文报道了a-Si:H/a-SiNx:H超晶格薄膜光致发光某些性质的研究。实验发现,这种超晶格薄膜光致发光的强度和峰值能量随交替层a-Si:H厚度,测量温度及光照时间等而变化。同时还发现,在阴、阳两极上,利用GD法沉积的样品,发光强度和峰值能量也有所不同。文中对这些实验结果作了初步解释。 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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本文从a-Si:H体材料的缺陷态模型出发,考虑在a-Si:H/a-SiN: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。 相似文献
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B. Abeles T. Tiedje H.C. Stasiewski H.W. Deckman P.D. Persans K.S. Liang C.B. Roxlo 《Superlattices and Microstructures》1985,1(2):115-118
The structural and electronic properties of a new class of superlattices consisting of layers of a-Si:H 8–1200 thick interleaved with a-Ge:H, a-Si1?xCx:H or a-SiNx:H are reviewed. 相似文献
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We report changes in optical absorption and Raman spectra of a-Ge:H when H content is increased from 0 to 16 atomic %. Increasing H content increases the optical gap by 0.4eV, sharpens the absorption tail by a factor of two and decreases bond angle fluctuations by 20. We conclude that H can affect the optical edge by decreasing network disorder. 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 photoluminescence of glow discharge deposited a-Ge:H is studied. The spectra exhibit a two-band structure with an intrinsic band centered at 0.65 eV and a defect induced band near 0.5 eV, which is enhanced by using less favorable deposition conditions (low substrate temperature) and by hydrogen effusion. Even in films of good quality the quantum efficiency is only about 1 % of that of good a-Si:H-films. It is suggested that the non-radiative recombination centers are Ge- dangling bonds and that the low efficiency as compared to a-Si:H-films of similar defect density is due to the larger localization length of the db-states which enhances radiationless tunneling processes. 相似文献
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Hydrogenated amorphous-Si/SiO2 (a-Si:H/SiO2) superlattices with different a-Si : H thickness in the range of a few nanometers have been fabricated by ultra high vacuum evaporator (UHV evaporator). The photoluminescence (PL) of our superlattices is observed in the visible spectral region and the peak energy shifts to higher energy as the a-Si : H layer thickness decreases. The temperature dependence of the PL spectra reveals four sub-bands by fitting. Bands at 2.2, 1.9, 1.65 and 1.45 eV are detected and are attributed to E′δ centers, nonbridging-oxygen–hole centers (NBOHC), Si/SiO2 interface and a-Si : H layer, respectively. We explain the overall blueshift of the PL spectra by the modification of the contribution of these sub-bands. 相似文献
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Amorphous thin-film solar cells 总被引:1,自引:0,他引:1
W. Krühler 《Applied Physics A: Materials Science & Processing》1991,53(1):54-61
This report gives an overview of the present status of thin-film solar cells made from hydrogenated amorphous semiconductors (a-Si:H, a-Ge:H) together with new results emphasizing the physics of amorphous materials and devices. Preparation techniques, quality and performances of a-Si:H and a-Ge:H films as well as solar cells with pin structures are reviewed. Dark and light current-voltage I(V) characteristics and spectral response measurements give information about photovoltaic diodes and allow further insights into the physics of these kinds of materials and solar cells. Simulation calculations and device modelling of such solar cells have increased our understanding of amorphous semiconductors and their devices. The introduction of pin/pin stacked and/or tandem structures has improved the long-term stability and conversion efficiency of amorphous solar cells.Dedicated to H.-J. Queisser on the occasion of his 60th birthday 相似文献