溶液法铝诱导晶化制备多晶硅薄膜

采用铝（Al）盐溶液作为诱导源进行了非晶硅晶化成多晶硅的研究.光学显微镜观测与Raman光谱分析表明,合适配比的铝盐溶液能够将非晶硅予以诱导晶化.采用剥层XPS测试分析,探究了Al盐溶液与硅表面可能的化学反应以及随之发生的硅-铝层交换的过程.最后对溶液法诱导晶化的机理进行了讨论. 关键词： 铝诱导晶化 多晶硅薄膜 溶液法     

金属诱导低温制备多晶硅薄膜工艺新进展

多晶硅薄膜由于兼具稳定性、高光敏性、便于大面积沉积等优势成为目前光伏领域的研究热点.本文综述了近几年金属诱导非晶硅薄膜晶化的新工艺,介绍了各种工艺条件对多晶硅薄膜材料的结构、金属含量的调控规律.最后展望了未来的发展趋势.     

磁控共溅射低温制备多晶硅薄膜及其特性研究

多晶硅在光电子器件领域具有较为重要的用途。利用磁控溅射镀膜系统,通过共溅射技术在玻璃衬底上制备了非晶硅铝(α-Si/Al)复合膜,将Al原子团包覆在α-Si基质中,膜中的Al含量可通过Al和Si的溅射功率比来调节。复合膜于N₂气氛中进行350 ℃,10 min快速退火处理,制备出了多晶硅薄膜。利用X射线衍射仪、拉曼光谱仪和紫外-可见光-近红外分光光度计对多晶硅薄膜的性能进行表征,研究了Al含量对多晶硅薄膜性能的影响。结果表明：共溅射法制备的α-Si/Al复合膜在低温光热退火下晶化为晶粒分布均匀的多晶硅薄膜;随着膜中Al含量逐渐增加,多晶硅薄膜的晶化率、晶粒尺寸逐渐增加,带隙则逐渐降低;Al/Si溅射功率比为0.1时可获得纳米晶硅薄膜,Al/Si溅射功率比为0.3时得到晶化率较高的多晶硅薄膜,通过Al含量的调节可实现多晶硅薄膜的晶化率、晶粒尺寸及带隙的可控。     

化学源金属诱导多晶硅研究

以硝酸镍溶液为化学源，对于用不同方法沉积得到的非晶硅膜作晶化前驱物，都能予以不同程度的晶化.用VHF-PECVD方法获得的非晶硅膜作前驱物，易于去氢并更容易晶化.当化学源浓度不同时，晶化效果会存在一定差别，在一定的范围内，溶液浓度越高，晶化后形成的晶粒越大.退火气氛对晶化结果产生某些影响，可以发现，在N₂气氛下退火，比在大气下有更好的晶化效果.最后对物理源与化学源作诱导金属的晶化结果进行了比较，结果表明，对诱导金属源而言，化学源显示出更为有效的晶化趋势. 关键词： 金属诱导晶化 多晶硅薄膜 低温制备 退火处理     

退火对Ge诱导晶化多晶Si薄膜结晶特性的影响

本文采用磁控溅射法, 衬底温度500 ℃下在硅衬底上分别制备具有Ge填埋层的a-Si/Ge 薄膜和a-Si薄膜, 并进行后续退火, 采用Raman光谱、X射线衍射、原子力显微镜及场发射扫描电镜等对所制薄膜样品进行结构表征. 结果表明, Ge有诱导非晶硅晶化的作用, 并得出以下重要结论: 衬底温度为500 ℃时生长的a-Si/Ge薄膜, 经600 ℃退火5 h Ge诱导非晶硅薄膜的晶化率为44%, 在相同的退火时间下退火温度提高到700 ℃, 晶化率达54%. 相同条件下, 无Ge填埋层的a-Si薄膜经800 ℃退火5 h薄膜实现晶化, 晶化率为46%. 通过Ge填埋层诱导晶化可使在相同的条件下生长的非晶硅晶薄膜的晶化温度降低约200 ℃. Ge诱导晶化多晶Si薄膜在Si(200)方向具有高度择优取向, 且在此方向对应的晶粒尺寸约为76 nm. 通过Ge诱导晶化制备多晶Si薄膜有望成为制备高质量多晶Si薄膜的一条有效途径.     

用镍硅氧化物源横向诱导晶化的多晶硅薄膜

采用磁控溅射法,以镍硅合金为靶,制备了一种适用于金属诱导横向晶化的氧化物镍源——自缓释镍源.该镍源在内部构成和晶化现象上都不同于纯金属镍源.采用该镍源制备低温多晶硅材料,晶化速率不明显依赖于镍源薄膜的厚度,且晶化多晶硅膜内的残余镍量亦可有效降低,可为薄膜晶体管提供宽的工艺窗口.本文对用纯金属镍源所得多晶硅薄膜的晶化率、表面粗糙度、电学特性等与溅射条件的关系进行了研究,并对相应结果进行了讨论.     

用镍硅氧化物源横向诱导晶化的多晶硅薄膜

采用磁控溅射法,以镍硅合金为靶,制备了一种适用于金属诱导横向晶化的氧化物镍源——自缓释镍源.该镍源在内部构成和晶化现象上都不同于纯金属镍源.采用该镍源制备低温多晶硅材料,晶化速率不明显依赖于镍源薄膜的厚度,且晶化多晶硅膜内的残余镍量亦可有效降低,可为薄膜晶体管提供宽的工艺窗口.本文对用纯金属镍源所得多晶硅薄膜的晶化率、表面粗糙度、电学特性等与溅射条件的关系进行了研究,并对相应结果进行了讨论. 关键词： 自缓释 金属诱导横向晶化 多晶硅薄膜 低温制备与退火     

铝诱导层交换超薄多晶硅薄膜制备及压阻特性

超薄多晶硅薄膜具有优异的压敏特性。铝诱导层交换(ALILE)制备多晶硅薄膜具有成膜温度低薄膜性能优良等特点。利用ALILE方法在玻璃基底上低温条件下制备了50 nm超薄多晶硅(poly-Si)薄膜,并对薄膜微观结构及压阻特性进行了研究。Raman光谱在521 cm-1出现尖锐、对称的特征峰,表明超薄多晶硅薄膜晶化状态良好。此外,在拉曼光谱480 cm-1处没有明显出现a-Si的Raman特征峰也说明制备的poly-Si薄膜样品完全结晶;XRD光谱表明ALILE制备薄膜在(111)和(220)晶向择优生长,晶粒尺寸约5 μm;霍尔效应测试结果表明：ALILE制备薄膜为p型掺杂,空穴浓度为9×1018～6×1019 cm-3;压阻特性研究表明：ALILE超薄多晶硅薄膜应变系数(GF)达到了60以上,且与薄膜厚度相关;应变温度相关系数(TCGF)在-0.17～0%℃范围内;电阻温度相关系数(TCR)在-0.2～-0.1%℃范围内。ALILE超薄多晶硅薄膜具有GF大、TCGF小和TCR小等特点。因此,有望在压力传感器领域得到应用。     

大尺寸化学Ni源金属诱导晶化多晶硅的研究

用无电电镀的化学方法，在VHF-PECVD沉积获得的非晶硅薄膜表面形成镍诱导源，在550℃下退火若干小时，可以诱导产生微米量级的多晶硅晶粒.用此法形成的镍源可以均匀地分布在非晶硅薄膜的表面.非晶硅薄膜上形成晶核的数量取决于镍溶液的浓度、pH值和无电电镀的时间等参量.当成核密度比较低时可以观察到径向晶化现象.用VHF-PECVD非晶硅薄膜作为晶化前驱物，晶化后多晶硅的最大晶粒尺寸可达到90μm.用此多晶硅试制的TFT，获得了良好的器件特性. 关键词： 金属诱导晶化 化学源 多晶硅 薄膜晶体管     

不同形貌衬底上铝诱导poly-Si薄膜的制备及表征

以表面平整、粗糙的玻璃为衬底,在不同衬底温度下直流磁控溅射沉积a-Si薄膜,制备成glass/a-Si/Al样品,经退火处理制备了poly-Si薄膜。分别采用Raman光谱、XRD光谱等手段研究了衬底粗糙度以及衬底温度对铝诱导晶化(AIC)制备的poly-Si品质的影响。Raman光谱表明：所有样品在521 cm-1都有尖锐、对称的Raman峰出现,表明样品完全结晶;XRD结果表明：poly-Si在(111)晶向择优生长;XRD在(111)处的半高宽值(FWHM)表明：玻璃衬底的形貌和a-Si沉积的温度对poly-Si的品质产生影响。200 ℃可能是AIC制备poly-Si薄膜时沉积a-Si时的最适温度。     

Fabrication of polycrystalline silicon films by Al‐induced crystallization of silicon‐rich oxide films

Polycrystalline silicon (poly‐Si) films were fabricated by aluminum (Al)‐induced crystallization of Si‐rich oxide (SiO_x) films. The fabrication was achieved by thermal annealing of SiO_x /Al bilayers below the eutectic temperature of the Al–Si alloy. The poly‐Si film resulting from SiO_1.45 exhibited good crystallinity with highly preferential (111) orientation, as deduced from Raman scattering, X‐ray diffraction, and transmission electron microscopy measurements. The poly‐Si film is probably formed by the Al‐induced layer exchange mechanism, which is mediated by Al oxide.     

多晶硅薄膜低温生长中晶粒大小的控制

以SiCl4H2为气源,用等离子体增强化学气相沉积(PECVD)方法低温快速沉积多晶硅薄膜.实验发现,在多晶硅薄膜的生长过程中,气相空间各种活性基团的相对浓度是影响晶粒大小的重要因素,随功率、H2/SiCl4流量比的减小和反应室气压的增加,晶粒增大.而各种活性基团的相对浓度依赖于PECVD工艺参数,通过工艺参数的改变,分析生长过程中空间各种活性基团相对浓度的变化,指出“气相结晶”过程是晶粒长大的一个重要因素. 关键词： 气相结晶 多晶硅薄膜 晶粒生长 SiCl4     

Poly-Si films with low aluminum dopant containing by aluminum-induced crystallization

Typically, highly p-doped (2×10 18 cm -3 ) poly-Si films fabricated by the aluminum induced layer exchange (ALILE) process are not suitable for solar cell absorber layers. In this paper, the fabrication of high-quality, continuous polycrystalline silicon (poly-Si) films with lower doping concentrations (2×10 16 cm -3 ) using aluminum-induced crystallization (AIC) is reported. Secondary-ion-mass spectroscopy (SIMS) results showed that annealing at different temperature profiles leads to a variety of Al concentrations. Hall Effect measurements revealed that Al dopant concentration depends on the annealing temperature and temperature profile. Raman spectral analysis indicated that samples prepared via AIC contain some regions with small grains.     

Identification of intra‐grain and grain boundary defects in polycrystalline Si thin films by electron paramagnetic resonance

We investigate the characteristics of intra‐grain and grain boundary defects in polycrystalline Si films, by employing quantitative electron paramagnetic resonance measurements on liquid phase crystallized layers with an average grain size of 200 µm and tailored solid phase crystallized Si layers with similar intra‐grain morphology but systematically varied grain sizes between 0.25 µm and 1 µm. The defect characteristics are found to be composed of two distinctive g ‐values of g = 2.0055 and 2.0032, which are attributed to grain boundary defects and intra‐grain defects, respectively. Additional hydrogenation leads to a reduction of the overall defect concentration, while a rapid thermal annealing process primarily heals intra‐grain defects.

     

Impact of the firing temperature profile on light induced degradation of multicrystalline silicon

Light‐ and elevated temperature‐induced degradation in multicrystalline silicon can reduce the efficiency of solar cells significantly. In this work, the influence of the firing process and its temperature profile on the degradation behaviour of neighbouring mc‐Si wafers is analysed. Five profiles with measured high peak temperatures ≥800 °C and varying heating and cooling ramps are examined. With spatially resolved and lifetime calibrated photoluminescence images, normalized defect concentrations N^*_t are calculated to determine the degradation intensity. Wafers that underwent a fast firing process typical for industrial solar cell production show a significantly stronger degradation than samples that were subjected to the same peak temperature but with slower heating and cooling rates. A spatially resolved analysis of the carrier lifetime in the whole wafer shows that the degradation begins in low lifetime areas around dislocation clusters, spreading into good grains after several hours. By the use of optimized ramp‐up and/or ramp‐down rates during the firing even at very high peak temperatures, light and elevated temperature induced degradation can be suppressed. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)