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采用甚高频等离子体辅助化学气相沉积技术(VHF-PECVD)分别对薄膜沉积参数进行了功率密度-沉积气压和硅烷浓度-气体总流量两因素优化.主要研究沉积参数对薄膜沉积速率和结晶状况的影响,结果表明:高沉积压强下,功率密度的提高对微晶硅薄膜(μc-Si∶H)沉积速率的影响减弱,硅烷浓度和气体总流量影响作用相对增强,高硅烷浓度有利于材料的利用,最终在高压强(600Pa)条件下,使微晶硅薄膜的沉积速率提升到2.1nm·s-1.同时,利用分步沉积法对薄膜的纵向结构均匀性进行了初步研究. 相似文献
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本文采用VHF-PECVD技术制备了两个不同硅烷浓度(SC)系列的微晶硅薄膜,通过椭圆偏振技术研究了微晶硅薄膜的微结构和表面粗糙度随沉积时间的变化。实验结果表明:随着薄膜厚度的增加,两个系列硅薄膜的晶化度增加,当薄膜增加到一定厚度时内部开始出现微空洞,这是由于随着薄膜厚度的增加,薄膜晶化度增加,晶粒增大,大晶粒边界之间更容易形成空洞。硅薄膜的表面粗糙层厚度ds与薄膜厚度d满足指数关系:ds~dβ,β为生长指数,与薄膜生长机制有关,当硅烷浓度SC为4%时,β=0.33,对应有限扩散生长模式。硅烷浓度SC为5%时,β=0.52,对应为零扩散随机生长模式。硅烷浓度降低,生长指数β减小,这是由于随着硅烷浓度的降低,氢原子浓度增加,薄膜表面氢覆盖扩大,从而有利于反应前驱物的扩散,因此薄膜表面更为光滑,生长指数β减小。 相似文献
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n型层对柔性衬底微晶硅太阳电池特性的影响 总被引:1,自引:0,他引:1
在不锈钢柔性衬底上采用等离子体化学气相沉积(PECVD)方法制备了不同结构的n型硅薄膜,测试了在其上生长的微晶硅太阳电池的电学输出特性.发现太阳电池的开路电压随n型层的硅烷浓度线形变化,短路电流密度则存在一个最优值,这与n型层引起的本征层中的孵化层和结构演变有关.将优化后的n型层应用于不锈钢柔性衬底的非晶硅/微晶硅叠层... 相似文献
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通过改变硅烷浓度,采用等离子体增强化学气相沉积方法制备了在有无金属屏蔽罩两种情况下的系列微晶硅太阳电池,发现将金属屏蔽罩去除后,本征微晶硅材料的沉积速率提高约一倍,微晶相至非晶相的硅烷浓度转变点有所变化。将沉积条件应用于不锈钢柔性衬底的非晶硅/微晶硅叠层太阳电池,获得了9.28%(AM0,1353 W/m2)和11.26%(AM1.5,1000W/m2)的光电转换效率。 相似文献
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采用VHF—PECVD技术沉积硼掺杂的P型微晶硅薄膜材料,在硅烷浓度(SC)为0.8%,反应气压93Pa时,随等离子体功率的增加,材料的晶化率和电导率先增大,后减小;薄膜的透过率随功率的增大而增加。将获得的P型微晶硅薄膜应用在微晶硅薄膜太阳电池中,电池结构为glass/pμc-Si:H/I-μe-Si:H/n-μc-Si:H/Al,厚度约1μm,没有背反射电极的情况下,电池效率达到了7.32%(Voc=0.520V,Jsc=21.33mA/cm^2,FF=64.74%)。 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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水三相点是开尔文热力学温度的唯一基准点,也是ITS-90国际温标重要的定义固定点。因此,水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来,中国计量科学研究院研制出一系列高质量的水三相点容器,加强了水三相点的研究,为不确定度的分析提供了更为可靠的实验依据。同时,不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此,根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明,其扩展不确定度为0.16mK(k=2.69,P=0.99)。 相似文献
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