共查询到20条相似文献,搜索用时 62 毫秒
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鉴于微晶硅薄膜在沉积过程中先经历一个非晶过渡层才开始晶化的生长特点,试图通过降低薄膜的沉积速率来延长沉积原子在薄膜生长表面的扩散时间,以达到促进晶粒生长的目的。研究结果表明,反应气体气流量的减小可以有效降低薄膜的沉积速率;随着沉积速率的降低,薄膜的表面粗糙度明显减小,且其平均晶粒尺寸有所增大,通过HRTEM甚至能观察到尺寸在10nm以上的晶粒,说明沉积速率的降低对沉积粒子在薄膜生长表面的扩散过程有较大影响;另外,薄膜的少子寿命随着沉积速率的降低逐渐增大,这与薄膜结晶程度和平均晶粒尺寸的变化趋势一致,可见微观结构对电学性能起着决定作用。 相似文献
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为了实现低成本微晶硅薄膜的高速沉积,需要尽可能的优化工艺参数,特别是提高功率利用效率对于降低生产成本,以及提高工艺稳定性都具有重要的意义.文中对射频等离子体增强化学气相沉积系统的各部分功率消耗进行了测量与分析,发现实际用于辉光放电的功率利用率仅为10%以下;腔室的寄生电阻自身消耗功率占30%左右,且寄生电抗分布情况对匹配器的功率消耗影响较大.通过对系统硬件的改造,降低了寄生电抗的影响,显著地提高了功率耦合效率,在高反应气压条件下的功率利用率达到60%以上. 相似文献
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不同沉积速率微晶硅薄膜生长模式的蒙特卡洛模拟研究 总被引:2,自引:1,他引:1
采用标度理论比较了不同速率下微晶硅薄膜的生长模式。结果是:低速时薄膜的生长指数为0.19,高速时薄膜的生长指数为0.61,两者生长机理明显不同。通过蒙特卡洛模拟薄膜生长过程,结果表明:生长基元的粘附系数和扩散能力对不同生长速率下薄膜的生长有较大的影响。 相似文献
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S. Okur M. Güneş O. Göktaş F. Finger R. Carius 《Journal of Materials Science: Materials in Electronics》2004,15(3):187-191
Steady-state photocarrier grating (SSPG) and steady-state photoconductivity, ph, experiments have been carried out to investigate the electronic transport properties of undoped hydrogenated microcrystalline silicon (c-Si : H) films prepared with very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD). Material with different crystalline volume fractions was obtained by variation of the silane concentration (SC) in the process gas mixture. Pure amorphous silicon material was investigated for comparison. The ambipolar diffusion length, Lamb, which is dominated by the minority carrier properties, is obtained both from the best fit to the experimental photocurrents ratio, , versus grating period (), and from the Balberg plot for the generation rates between 1019 and 1021 cm–3 s–1. Lamb increases from 86 nm with increasing SC and peaks around 200 nm for the SC=5.6% and decreases again for higher SCs. Lamb values obtained from the intercept of the Balberg plot result in a small difference of around 5% for most of the samples. Minority carrier mobility-lifetime ()-products are much lower than those of majority carriers, however, both majority and minority carrier -products in microcrystalline silicon are higher than those of undoped hydrogenated amorphous silicon. The grating quality factor (0) changes from 0.70 to 1.0 indicating almost negligible surface roughness present in the samples. 相似文献
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Mehmet Günesç R. E. Johanson S. O. Kasap F. Finger A. Lambertz 《Journal of Materials Science: Materials in Electronics》2003,14(10-12):731-732
Coplanar conductance fluctuations or excess noise of undoped hydrogenated microcrystalline silicon (μc-Si : H) thin films grown by VHF-PECVD from silane–hydrogen mixtures with silane concentrations from 2% to 6% have been studied between room temperature and 470 K. We report that undoped μc-Si : H thin films show similar noise-power spectra to those of undoped a-Si : H films in a coplanar sample geometry. At lower temperatures, the noise with the slope α=0.60±0.07 and at higher temperatures, the noise with the slope α close to unity dominate the spectrum. The noise magnitude decreases with decreasing silane concentration and becomes strongly temperature dependent with increased crystallinity. 相似文献
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Zhimeng Wu Qingsong Lei Jianping Xi Ying Zhao Xinhua Geng 《Journal of Materials Science》2006,41(6):1721-1724
Intrinsic microcrystalline silicon films have been prepared with very high frequency plasma enhanced chemical vapor deposition
(VHF-PECVD) from silane/hydrogen mixture at 180°C. The effect of silane concentration and discharge power on the growth of
silicon films was investigated. Samples were investigated by Fourier transform infrared spectroscopy, Raman scattering and
X-ray diffraction. The Raman spectrum shows that the morphological transition from microcrystalline to amorphous occurs under
conditions of high silane concentration and low discharge power. X-ray diffraction spectra indicate a preferential growth
direction of all microcrystalline silicon films in the (111) plane. In addition, a solar cell with an efficiency of 5.1% has
been obtained with the intrinsic microcrystalline layer prepared at 10W. 相似文献
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G. Ekanayake 《Vacuum》2006,81(3):272-278
Al-induced crystallisation of microcrystalline Si thin films prepared by electron cyclotron resonance plasma-enhanced chemical vapour deposition (ECR-PECVD) on glass and SiO2 coated Si wafers has been studied. The starting structure was substrate/μc-Si/Al. Annealing this structure in the temperature range 370-520 °C, immediately following deposition of the Al layer, resulted in successful layer exchange and the formation of a substrate/Al+Si layer/poly-Si geometry. The top poly-Si layer exhibited grain sizes generally in the range ∼2-6 μm, although larger grains were also sparsely present. The films did not exhibit any appreciable degree of preferred orientation. The surface roughness was relatively high with a Ra value of ∼20 nm. 相似文献
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He ZhangXiaodan Zhang Changchun WeiJian Sun Xinhua GengShaozhen Xiong Ying Zhao 《Thin solid films》2011,520(2):861-865
We applied ex situ spectroscopic ellipsometry (SE) on silicon thin films across the a-Si:H/μc-Si:H transition deposited using different hydrogen dilutions at a high pressure by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD). The optical models were based on effective medium approximation (EMA) and effective to estimate the thickness of the amorphous incubation layer and the volume fractions of amorphous, microcrystalline phase and void in μc-Si:H thin films. We obtained an acceptable data fit and the SE results were consistent with that from Raman spectroscopy and atomic force microscopy (AFM). We found a thick incubation layer in μc-Si:H thin films deposited at a high rate of ~ 5 Å/s and this microstructure strongly affected their conductivity. 相似文献
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M. Güneş D. Akdaş O. Göktaş R. Carius J. Klomfass F. Finger 《Journal of Materials Science: Materials in Electronics》2003,14(10-12):729-730
Steady-state photoconductivity and sub-bandgap absorption measurements by the dual-beam photoconductivity (DBP) method were carried out on undoped hydrogenated microcrystalline silicon thin films prepared by VHF-PECVD and hot-wire chemical vapor deposition. The results are compared with those of the constant-photocurrent method (CPM) and photothermal deflection spectroscopy (PDS). It is found that DBP, CPM, and PDS provide complementary data on the optoelectronic processes in microcrystalline silicon. 相似文献
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In order for hot-wire chemical vapor deposition to compete with the conventional plasma-enhanced chemical vapor deposition technique for the deposition of microcrystalline silicon, a number of key scientific problems should be cleared up. Among these points, the concentration of tungsten (nature of the filament), as well as the concentration of oxygen and carbon (elements issued when vacuum is broken between two runs), should not exceed threshold values, beyond which electronic properties of the films could be degraded, as in the case of monocrystalline silicon. Quantitative chemical analysis of these elements has been carried out using the secondary ion mass spectrometry technique through depth profiles. It has been shown that for a high effective filament surface area (Sf=27 cm2), the W content increases steadily from 5×1014 to 2×1018 atoms cm−3 when the filament temperature Tf increases from 1500 to 1800 °C. For a fixed Tf, the W content increases with the effective surface area Sf. Thus, considering our reactor geometry, the W content does not exceed the detection limit (5×1014 atoms cm−3) when Tf and Sf are limited to 1600 °C and 4 cm2, respectively. For O and C elements, under deposition conditions of high dilution of silane in hydrogen (96%), O and C concentrations approaching 1020 atoms cm−3 have been obtained. The introduction of an inner vessel inside the reactor, the addition of a load-lock chamber and a decrease in substrate temperature to 300 °C have led to a drastic decrease in these contents down to 3×1018 atoms cm−3, compatible with the realization of 6% efficiency HWCVD μc-Si:H solar cells. 相似文献
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H. R. Moutinho C. -S. Jiang J. Perkins Y. Xu B. P. Nelson K. M. Jones M. J. Romero M. M. Al-Jassim 《Thin solid films》2003,430(1-2):135-140
We deposited microcrystalline silicon (μc-Si) by hot-wire chemical vapor deposition (HWCVD) at different thickness and dilution ratio, with and without seed layer. As the dilution ratio increased, we observed an increase in the amount of microcrystalline phase in the film, a change in the structure of the grains and a loss of the (220) preferential orientation. The films deposited over a seed layer had a larger fraction of crystalline phase than films deposited with the same parameters but without a seed layer. For high dilution ratios (R=100), most of the film grows epitaxially at the interface with the Si substrate, but a microcrystalline film slowly replaces the single-crystal phase. For low dilution ratios (R=14), the film starts growing mostly amorphously, but the amount of crystalline phase increases with thickness. 相似文献
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A. M. Nardes A. M. de Andrade F. J. Fonseca E. A. T. Dirani R. Muccillo E. N. S. Muccillo 《Journal of Materials Science: Materials in Electronics》2003,14(5-7):407-411
In this paper, we present the characterization results of doped n-type microcrystalline hydrogenated-silicon (c-Si : H) films deposited in a plasma-enhanced chemical vapor deposition in the temperature range between 70 and 250 °C. The interest in these films arises from the fact that they combine the high optical absorption of amorphous silicon with the electronic behavior of the crystalline silicon, making them interesting for the production of large electronic devices such as solar cells, image sensors, and flat panels. It is shown that n-type c-Si : H films with high electrical conductivity can be obtained even at low temperature deposition, around 120 °C (=2.9 S cm–1). The structural properties of the films have been studied by Raman and infrared spectroscopy that allowed for the determination of the crystalline fraction. Electrical measurements were performed by a.c. impedance spectroscopy, Hall effect, and dark conductivity. Characteristics suitable for application in electronic devices were obtained with the developed deposition parameters set-up; the best dark conductivity values were around 1 S cm–1 for deposition temperatures within the 120–140 °C range. Some conclusions regarding the correlation between electrical and structural properties are presented for the considered temperature range. 相似文献