氮化硅薄膜对硅片背表面的钝化作用

采用等离子体增强化学沉积的方法(PECVD),在低衬体温度下制备不同厚度的双面氮化硅薄膜,通过准稳态电导法(QSSPCD)测试non-diffused和diffused硅片沉积不同厚度双面氮化硅薄膜烧结前后的少子寿命,研究发现,氮化硅薄膜厚度在17 nm左右的时候,背面钝化效果有所下降,超过26 nm的时候,效果基本一致.non-diffused烧结后的少子寿命下降很大,而diffused与之相反.结果表明,采用氮化硅作为背面钝化介质膜,可以改善材料的少子寿命,背面钝化膜可以选择在26～75 nm之间.     

热处理对氮化硅薄膜光学和电学性能的影响

使用PECVD在单晶硅硅片表面沉积了非晶氮化硅(a-SiNx∶H)薄膜,采用传统的退火炉和快速热退火炉进行了不同时间和温度下的退火比较,并研究了退火对薄膜光学性能以及材料少子寿命的影响。研究发现:氮化硅薄膜经热处理后厚度降低,折射率先升高后降低;沉积氮化硅薄膜后400℃退火可以促进氢扩散,提高少子寿命,超过400℃后氢开始逸失,衬底少子寿命急剧下降。另外,还发现RTP处理过程中氢的逸失比常规热处理快。     

多晶硅太阳电池预处理及退火工艺研究

在沉积氮化硅薄膜之前采用氨气电离出氢等离子体,先对硅片进行氢等离子体预处理,通过数值分析和实验方法分别研究预处理时间、功率、温度、压力等各参数对钝化效果以及电学性能的影响。在预处理温度450℃,时间200s,射频功率4000W,气体压强200Pa,氨气流量4000sccm/min时,短路电流提高约4%。采用等离子体增强型的化学气相沉积(PECVD)法,在电池表面镀上一层氮化硅膜,实验证实氢等离子体会透过氮化硅进入到硅基体内,从而使少子寿命提高约5μs。低温退火实验表明,430~440℃为最优温度,随时间的增加,短路电流有明显提升。     

管式PECVD法沉积的SiyNx/SiOxNy叠层膜的研究

本文对采用管式等离子体增强化学气相沉积(PECVD)法沉积的氮化硅与氮氧化硅(Si_yN_x/SiO_xN_y)叠层膜进行了实验研究,结果表明:在硅片正面镀膜时增加SiO_xN_y膜层,既可以增强正面的钝化效果,还可以降低对光的反射率,增加光吸收率,从而提升太阳电池的短波响应能力,通过对膜层组分和反应气体流量等工艺参数进行匹配优化,使太阳电池的光电转换效率提升了0.07%;利用Si_yN_x/SiO_xN_y叠层膜抗氧化、抗钠离子的特性,使太阳电池的抗电势诱导衰减(PID)性能提升了22%。     

PECVD制备太阳电池氮化硅薄膜特性研究

含氢氮化硅薄膜在太阳电池工业生产领域被广泛的用作减反射层和钝化层。使用工业型等离子体增强化学气相沉积(PECVD)设备制备了含氢氮化硅薄膜,使用傅里叶红外光谱(FTIR)测试仪对薄膜成分进行分析,研究反应气体流量、高频电源功率对薄膜成分以及薄膜特性影响,并通过硅片的少子寿命研究氮化硅薄膜成分对硅片钝化效果的影响,明确实际工业生产中的工艺调整方向。     

晶体硅太阳电池Sin:H减反射层的大规模在线溅射镀膜

1引言 大多数多晶硅太阳电池的减反射膜都是用增强的等离子化学气相沉积法（PECVD）沉积的掺氢氮化硅膜层（Sinx：H）。和其它减反射膜（如二氧化钛）相比，Sinx：H的优点是它具有很好的表面和体钝化功能。除了这些优点之外，PECVD技术有几个显著的缺点，主要是PECVD工艺使用爆炸性气体以及维护周期较短，同时PECVD技术在大面积在线镀膜时的膜厚均匀性也存在问题，这些问题使人们对采用不同的沉积技术产生了兴趣。由于对不同材料在大面积基片上采用溅射镀膜具有高产能、良好的均匀性和较长的维护周期等优势，因此溅射技术成为在太阳电池片上沉积Sinx：H膜层的较为理想的方式。     

多晶硅太阳电池的等离子体预处理研究

采用H2、NH3和H2 NH3等离子体在沉积氮化硅薄膜之前对多晶硅片进行预处理,采用等离子增强化学气相沉积(PECVD)制备氮化硅薄膜,然后印刷烧结.利用准稳态光电导衰减法(QSSPCD)、傅里叶红外光谱仪(FT-IR)和紫外可见近红外分光光度计(UV-VIS)等手段研究了等离子体预处理对多晶硅少子寿命的影响以及等离子体预处理对氮化硅薄膜FTIR光谱的影响和多晶电池性能的影响.结果表明:经等离子体预处理后多晶硅的少子寿命有所提高,使用H2 NH3混合等离子体预处理后,制备的多晶电池的性能有明显提高,短路电流能提高约7%.     

管式PECVD设备的温控系统调节对镀膜均匀性的影响分析

以管式PECVD设备的温控系统调节对镀膜均匀性的影响为研究对象,通过实验研究的方法,分别研究了温控系统调节中温区的温度设置、加热时间设置、整体温度设置,以及舟片间距设置对管式PECVD设备镀膜均匀性的影响。研究结果表明:将炉口到炉尾的温度设置为依次降低的趋势,或增加加热时间,或整体温度降低都可以缩小内、外舟片的温度差异,进而均可以明显改善管式PECVD设备的镀膜均匀性;另外,利用舟片间距不等的石墨舟可以解决由固定舟片位置产生的色差问题,外舟片间距由11 mm调整到12 mm可以明显改善由于外舟片受热程度高而带来的膜厚及折射率偏高的情况。     

氮化硅薄膜对晶体硅材料和电池的钝化效果研究

利用等离子体增强化学气相沉积技术,在P型直拉单晶硅硅片和铸造多晶硅片以及太阳电池的表面上 沉积了非晶氮化硅(a-SiNx:H)薄膜,并研究了氮化硅薄膜对材料少子寿命和太阳电池性能的影响。研究发现: 氮化硅薄膜显著地提高了晶体硅材料中少子寿命,同时多晶硅太阳电池的开路电压有少量提高,短路电流普遍 提高了1mA/cm2,电池效率提高了2％。实验结果表明:氮化硅薄膜不仅具有表面钝化作用,也有良好的体钝化 作用。     

低频PECVD设备沉积的AlO_x/SiN_x钝化膜的性能研究

对低频PECVD设备沉积的应用于PERC太阳电池上的AlO_x/SiN_x钝化膜的性能进行了研究。通过少子寿命测试发现,低频PECVD设备直接沉积的AlO_x/SiN_x钝化膜的钝化性能较弱,载流子复合严重;利用傅里叶红外光谱(FTIR)对造成该现象的原因进行了分析,结果发现,一是因为Si-AlO_x界面无足够的氧化层,二是因为AlO_x膜层内的Al-O四面体结构占比偏小。通过在低频PECVD设备沉积AlO_x膜后通入N_2O/NH_3气体进行等离子体表面处理工艺,抑制了表面的载流子复合,显著改善了AlO_x/SiN_x钝化膜的钝化性能,使小批量生产的PERC太阳电池的平均转换效率达到了22.48%。     

板式PECVD设备维护后初期的生产品质提升方案

以板式PECVd设备维护后的初期在多晶硅片表面镀的氮化硅薄膜为研究对象,分析了其膜厚、折射率、腐蚀速率等数据,以及此种镀膜情况下制备的多晶硅太阳电池的电性能。结果表明:在设备维护后初期(约1h)镀制的氮化硅薄膜,随着时间的推移,氮化硅薄膜的膜厚不断下降,折射率随之上升,二者分别从第48 min和第56 min开始趋于稳定;将采用设备维护后64 min内制备的氮化硅薄膜的太阳电池的电性能与采用设备维护前64 min内制备的氮化硅薄膜的太阳电池的电性能进行对比后发现,前者的光电转换效率比后者的低0.05%,且设备维护后初期时制备的氮化硅薄膜的腐蚀速率偏高。通过监控角阀开度曲线,待角阀开度绝对值在中心值上下1%的范围内波动后再进行生产,可以避免设备维护后初期镀膜生产的太阳电池不良品的产生,对提高生产线良品率具有一定的指导意义。     

Silicon solar cells with antireflection diamond-like carbon and silicon carbide films

Optical properties of diamond-like carbon and silicon carbide (SiC) films in dependence on deposition conditions were investigated. It was established that the films having refractive index from 1.6 to 2.3 may be obtained. The film optical bandgap and hardness may be changed from 1.5 to 4 eV and from 1 to 20 GPa, correspondingly. The films were deposited onto the front side of silicon solar cells (SCs). It has been shown that deposition of single- or two-layer diamond-like carbon antireflection (AR) coatings enables the SCs efficiency to be improved 1.35–1.5 times. The improvement is connected with decreasing of reflection losses and passivation of recombination active centers. SiC AR coatings improve the solar cell efficiency up to 1.3 times.     

High-density inductively coupled plasma chemical vapor deposition of silicon nitride for solar cell application

The silicon nitride films were deposited by means of high-density inductively coupled plasma chemical vapor deposition in a planar coil reactor. The process gases used were pure nitrogen and a mixture of silane and helium. Passivated by silicon nitride, solar cells show efficiency above 13%. Strong H-atom release from the growing SiN film and Si–N bond healing are responsible for the improved electrical and passivation properties of SiN film. This paper presents the optimal refractive index of SiN for single layer antireflection coating as well as double layer antireflection coating in solar cell applications.     

Reduction of amorphous incubation layer by HCl addition during deposition of microcrystalline silicon by hot-wire chemical vapor deposition

The amorphous incubation layer, which is formed in the initial growth stage of hydrogenated microcrystalline silicon (μc-Si:H) thin film deposited at low temperature, is harmful to the electric properties of film. In this study, the effect of the addition of HCl gas on the reduction of such an amorphous incubation layer was investigated during the silicon deposition on a glass substrate at 220 °C by hot-wire chemical vapor deposition process using the Raman spectroscopy, the X-ray diffraction and the field-emission scanning electron microscopy. In the initial stage of deposition where the silicon film deposited without HCl addition consisted almost entirely of the amorphous incubation layer; highly crystalline silicon films could be deposited with HCl addition. As the flow rate of HCl increased, the crystallinity of silicon films increased but the film growth rate decreased. The surface morphology of films prepared with HCl addition became smoother with smaller grain size than that prepared without HCl.     

PECVD淀积氮化硅薄膜性质研究

使用等离子体增强化学气相沉积(Plasma Enhanced Chemical Vapor Deposition，PECVD)在P型硅片上沉积了氮化硅(SiNx)薄膜，使用薄膜测试仪观察了薄膜的厚度、折射率和反射光谱，利用扫描电子显微镜(SEM)，原子力显微镜(AFM)观察了截面和表面形貌，使用傅立叶变换红外光谱仪(FTIR)和能谱仪(EDX)分析了薄膜的化学结构和成分。最后，考察了薄膜在经过快速热处理过程后的热稳定性，并利用霍尔参数测试仪(Hall)比较了薄膜沉积前后载流子迁移率的变化。     

Development of n-μc-SiOx:H as cost effective back reflector and its application to thin film amorphous silicon solar cells

Development of doped silicon oxide based microcrystalline material as a potential candidate for cost-effective and reliable back reflector layer (BRL) for single junction solar cells is discussed in this article. Phosphorus doped μc-SiO_x:H layers with a refractive index ∼2 and with suitable electrical properties were fabricated by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique, using the conventional capacitively coupled reactors. Optoelectronic properties of these layers were controlled by varying the oxygen content within the film. The performance of these layers as BRL have been investigated by incorporating them in a single junction amorphous silicon solar cell and compared with the conventional ZnO:Al based reflector layer. Single junction thin film a-Si solar cells with efficiency ∼9.12% have been successfully demonstrated by using doped SiO:H based material as a back reflector. It is found that the oxide based back reflector shows analogous performance to that of conventional ZnO:Al BRL layer. The main advantage with this technology is that, it can avoid the ex-situ deposition of ZnO:Al, by using doped μc-SiO:H based material grown in the same reactor and with the same process gases as used for thin-film silicon solar cells.     

微晶硅薄膜的光稳定性与微结构的关系

利用甚高频等离子体增强化学气相沉积技术,通过改变功率密度和沉积压强制备了三系列微晶硅薄膜。采用拉曼光谱、XRD与电导率分析技术,研究在光照条件下微晶硅薄膜的光学特性,光电导衰退与晶化率、沉积速率、晶粒尺寸间的关系。研究发现:随着晶化率的增加,微晶硅薄膜的光电导衰退率逐渐减小;随着沉积气压的增加,相同晶化率的薄膜的光稳定性降低。在光照50h后,薄膜的光电导衰退基本达到饱和。     

Silicon sheet from silane: first results

A process to obtain self-supported thin silicon films is being developed. Films are grown by optical chemical vapour deposition (CVD) (using halogen lamps as heating system) from silane, at low temperature and relatively high growth rates, on silicon substrates with a sacrificial layer of porous Si (PS), which allows film detachment. The PS layer was formed by anodisation of the Si-substrate surface in a HF:ethanol solution. Film deposition was carried out in an optical cold wall horizontal CVD reactor, operating at atmospheric pressure, and specially designed for this study. Deposition rates and film morphology were studied as a function of substrate nominal temperature, gas concentration and flux. In the final chosen conditions, deposition occurs at a nominal temperature of 840°C, with a silicon growth rate between 2 and 4 μm/min, which is relatively high for the low temperature used. A good usage of silane gas was already achieved, with 80–85% of the silicon in the silane gas being deposited on a 40×40 mm² substrate, with very low deposition rate on the reactor wall. Films of thicknesses from 10 to 150 μm were deposited. The films were found to be continuous with surfaces coated with whiskers. Film detachment from multicrystalline substrates has proved unsuccessful so far, while it readily occurs when monocrystalline substrates are used. The reason for this is macropore collapse and film rupture, usually occurring in the smaller grain regions of the multicrystalline substrates.     

非晶孵化层对高速生长微晶硅电池性能的影响

采用高压高功率的甚高频等离子体增强化学气相沉积(VHF-PECVD)技术,以不同的反应气体总流量制备出沉积速率大于1nm/s、次带吸收系数(α0.8eV)小于2.5cm-1且具有相同晶化率的本征微晶硅薄膜,然而将其应用在微晶硅电池中时,电池性能却有明显差异.通过对微晶硅电池的光、暗态J-V,量子效率(QE)和微区拉曼(Raman)测试发现,微晶硅薄膜中非晶孵化层厚度的不同是引起电池性能差异的主要原因.反应气体总流量较低时沉积的微晶硅薄膜具有较厚的非晶孵化层,阻碍了载流子的输运,使电池的长波光谱响应下降,从而降低了电池的短路电流密度与填充因子;而增加总气体流量,有效减小了微晶硅薄膜中的非晶孵化层的厚度,从而使电池性能得到改善.最后在总气体流量为500sccm时,制备得到沉积速率为1nm/s,效率为7.3%的单结微晶硅太阳电池.