晶体硅太阳电池表面钝化技术

介绍了晶体硅太阳电池表面钝化技术的发展历程,表面钝化膜在晶体硅太阳电池中所起的作用,以及晶体硅太阳电池中各种钝化膜和表面钝化技术。阐述了国内和国际对晶体硅太阳电池表面钝化技术的最新研究动态,重点论述了SiO2,SiNx,SiCx和Al2O3,以及这些钝化膜的叠层钝化技术的优缺点。在此基础上进一步指出SiO2/SiNx叠层钝化膜将成为今后工业化生产的研究重点,Al2O3及其叠层钝化膜将成为今后实验室的研究重点,由于表面钝化是提高晶体硅太阳电池转换效率最有效的手段之一,今后晶体硅太阳电池表面钝化技术仍将是国内和国际研究的热点问题之一。     

氧化铝钝化在晶体硅太阳电池中的应用

首先,回顾了氧化铝钝化技术的发展历程,对制备氧化铝钝化薄膜的手段进行了总结,并且详细描述了氧化铝的材料性质和钝化的机理。其次,指出氧化铝薄膜的优点在于优异的场效应钝化特性和良好的化学钝化性质,因此可以应用于低掺和高掺p型硅表面的钝化。此外,氧化铝薄膜及其叠层还具有良好的热稳定性,符合丝网印刷太阳电池的要求。最后,总结了氧化铝薄膜钝化技术在晶体硅太阳电池中的最新研究动态,指出氧化铝钝化薄膜用于工业生产中存在的问题,并针对这些问题提出了有效的解决方案。     

n型晶体硅太阳电池光诱导衰减现象研究

基于n型晶体硅太阳电池,分析了经光辐照后电池各性能参数的变化,探究了n型晶体硅太阳电池光诱导衰减机理.使用工业化设备在大面积(156 mm×156 mm)n型单晶硅片上制备太阳电池.利用太阳光谱模拟仪对制备的太阳电池进行光照处理,对比各阶段太阳电池电性能参数.结果表明,光照时会导致太阳电池表面减反射膜SiN:H/Si界面处积聚大量固定电荷,增大界面态密度,破坏电池表面钝化层结构,导致开路电压和短路电流产生较大衰减,35 kWh/m2光辐照后n型硅太阳电池效率衰减3.6％.在380℃低温退火处理后电池效率基本可恢复到初始状态.内量子效率测试结果表明光辐照后电池短波区域响应减弱,前表面界面效应导致电池效率发生较大衰减.     

Hydrogen Passivation in Mc-Si for Solar Cells

The effect of hydrogen passivation on multicrystalline silicon (mc-Si) used for solar cells is described, and the mechanism of hydrogen diffusion and passivation is also investigated. Then, the hydrogen passivation processes applied in industries and research laboratories are introduced. Finally the existing problems and the prospects of hydrogen passivation are reviewed.     

晶体硅中氢钝化硼的机理

利用量子化学近似计算方法MNDO和红外光谱法研究了晶体硅中氢和硼的相互作用.结果表明,原子氢束缚在离代位硼原子约1.25A的球面能谷中,可绕硼转动,形成一个动态的硼-氢复合体,从而钝化硼.B-H对的动态性质导致对应的1875cm~(-1)红外吸收峰的宽化,这种状态可保持到10K.     

Performance Enhancement of Crystalline Silicon Solar Cells by Coating with Luminescent Silicon Nanostructures

In this work we report a technique that is potentially capable of increasing the efficiency of crystalline silicon solar cells, which dominate the present-day market of photovoltaic devices. The simple and cost-effective method involves coating the surface of a commercially procured silicon solar cell with luminescent silicon nanocrystals. Core/shell silicon/silicon-oxide nanostructures are fabricated by an inexpensive and reproducible technique, where coarse silicon powders are repeatedly milled, oxidized, and etched until their sizes are reduced so as to exhibit room-temperature photoluminescence under ultraviolet excitation. A thin coating of these nanostructures on a standard solar cell, obtained by a simple dip-coating method, increases the open-circuit voltage and short-circuit current, which consequently increases the maximum power delivered by ~16.3% and efficiency by almost ～39%. We propose that the core/shell nanostructures act as luminescent convertors that convert higher-energy photons to lower-energy photons, thereby leading to less thermal relaxation loss of photoexcited carriers.     

Progress in Low-temperature Surface Passivation of Silicon Solar Cells using Remote-plasma Silicon Nitride

Using a remote-plasma technique as opposed to the conventional direct-plasma technique, significant progress has been obtained at ISFH in the area of low-temperature surface passivation of p-type crystalline silicon solar cells by means of silicon nitride (SiN) films fabricated at 350–400°C in a plasma-enhanced chemical vapour deposition system. If applied to the rear surface of the low-resistivity p-type substrates, the remote-plasma SiN films provide outstanding surface recombination velocities (SRVs) as low as 4 cm s⁻¹, which is by a clear margin the lowest value ever obtained on a low-resistivity p-Si wafer passivated by a solid film, including highest quality thermal oxides. Compared to direct-plasma SiN films or thermally grown oxides, the remote-plasma films not only provide significantly better SRVs on low-resistivity p-silicon wafers, but also an enormously improved stability against ultraviolet (UV) light. The potential of these remote-plasma silicon nitride films for silicon solar cell applications is further increased by the fact that they provide a surface passivation on phosphorus-diffused emitters which is comparable to high-quality thermal oxides. Furthermore, if combined with a thermal oxide and a caesium treatment, the films induce a UV-stable inversion-layer emitter of outstanding electronic quality. Due to the low deposition temperature and the high refraction index, these remote-plasma SiN films act as highly efficient surface-passivating antireflection coatings. Application of these films to cost-effective silicon solar cell designs presently under development at ISFH turned out to be most successful, as demonstrated by diffused p-n junction cells with efficiencies above 19%, by bifacial p-n junction cells with front and rear efficiencies above 18%, by mask-free evaporated p-n junction cells with efficiencies above 18% and by MIS inversion-layer cells with a new record efficiency of above 17%. All cells are found to be stable during a UV test corresponding to more than 4 years of glass-encapsulated outdoor operation. © 1997 John Wiley & Sons, Ltd.     

多晶硅太阳电池PECVD氮化硅钝化工艺的研究

介绍等离子体化学气相淀积(PECVD)制备减反射钝化膜。将PECVD设备运用于太阳电池生产线上,发现通过PECVD设备可以对多晶硅太阳电池有很好的钝化效果。分析PECVD对多晶硅太阳电池钝化机理。     

双层氮化硅减反、钝化结构对多晶硅太阳电池性能的影响

探究了多晶硅太阳电池表面双层氮化硅减反、钝化结构的产线工艺.示范性实验结果表明,直接与多晶硅接触的底层氮化硅的厚度是双层氮化硅减反、钝化能力的一个关键因素.相对于单层氮化硅减反、钝化的多晶硅太阳电池,厚度优化的双层氮化硅减反、钝化电池片的短路电流和开路电压均有所改善,相应的光电转换效率提升超过0.2％.光电转换效率的提升归因于双层氮化硅减反、钝化结构有利于降低光损失和表面钝化.     

背面银浆用银粉对晶硅太阳电池性能的影响

分别采用液相化学还原法和机械球磨法制得球形银粉和片状银粉,研究了银粉的形貌、分散性及振实密度对背面银浆烧结膜和电池光电性能的影响。结果表明:片状银粉制备的背银浆料附着力最好、电池光电转换效率最高,球形银粉次之,树枝型银粉最差。高分散和高振实密度银粉能显著提高电池片的光电转换效率。     

Improved Microwave Noise Performance by SiN Passivation in AlGaN/GaN HEMTs on Si

Effects of silicon nitride (SiN) surface passivation by plasma enhanced chemical vapor deposition (PECVD) on microwave noise characteristics of AlGaN/GaN HEMTs on high-resistivity silicon (HR-Si) substrate have been investigated. About 25% improvement in the minimum noise figure $(NF_{min})$ (0.52 dB, from 2.03 dB to 1.51 dB) and 10% in the associate gain $(G_{rm a})$ (1.0 dB, from 10.3 dB to 11.3 dB) were observed after passivation. The equivalent circuit parameters and noise source parameters (including channel noise coefficient $(P)$, gate noise coefficient $(R)$, and their correlation coefficient $(C)$ ) were extracted. $P$ , $R$ and $C$ all increased after passivation and the increase of C contributes to the decrease of the noise figure. It was found that the improved microwave small signal and noise performance is mainly due to the increase of the intrinsic transconductance $(g_{{rm m}0})$ and the decrease of the extrinsic source resistance $(R_{rm s})$.      

锗掺杂磁控直拉单晶硅太阳电池

介绍了锗掺杂浓度为(1～1.5)×1019cm-3的10Ω·cm磁控直拉单晶硅衬底上BSFR(back surface field and reflection)和BSR(back surface reflection)太阳电池的制备和电性能.BSR锗掺杂单晶硅太阳电池的AM0效率最高为12.3%.BSFR锗掺杂单晶硅太阳电池的AM0效率达到15%.利用1MeV的高能电子对制备的锗掺杂单晶硅太阳电池进行了辐照实验.作为对比,对全部常规10Ω·cm的CZ单晶硅太阳电池也进行了实验.结果表明,锗掺杂浓度为(1～1.5)×1019cm-3的磁控直拉单晶硅太阳电池的电性能和抗辐照性能与常规直拉硅太阳电池基本相同.利用锗掺杂磁控直拉单晶硅片机械强度较高的优点,可以降低太阳电池生产过程破损率.     

锗掺杂磁控直拉单晶硅太阳电池

介绍了锗掺杂浓度为(1～1.5)×1019cm-3的10Ω·cm磁控直拉单晶硅衬底上BSFR(back surface field and reflection)和BSR(back surface reflection)太阳电池的制备和电性能.BSR锗掺杂单晶硅太阳电池的AM0效率最高为12.3%.BSFR锗掺杂单晶硅太阳电池的AM0效率达到15%.利用1MeV的高能电子对制备的锗掺杂单晶硅太阳电池进行了辐照实验.作为对比,对全部常规10Ω·cm的CZ单晶硅太阳电池也进行了实验.结果表明,锗掺杂浓度为(1～1.5)×1019cm-3的磁控直拉单晶硅太阳电池的电性能和抗辐照性能与常规直拉硅太阳电池基本相同.利用锗掺杂磁控直拉单晶硅片机械强度较高的优点,可以降低太阳电池生产过程破损率.     

锗掺杂磁控直拉单晶硅太阳电池

介绍了锗掺杂浓度为（1～1.5) E19cm-3的10Ω·cm磁控直拉单晶硅衬底上BSFR (back surface field and reflection）和BSR(back surface reflection)太阳电池的制备和电性能. BSR锗掺杂单晶硅太阳电池的AM0效率最高为12.3%. BSFR锗掺杂单晶硅太阳电池的AM0效率达到15%. 利用1MeV的高能电子对制备的锗掺杂单晶硅太阳电池进行了辐照实验. 作为对比，对全部常规10Ω·cm的CZ单晶硅太阳电池也进行了实验. 结果表明，锗掺杂浓度为（1～1.5)E19cm-3的磁控直拉单晶硅太阳电池的电性能和抗辐照性能与常规直拉硅太阳电池基本相同. 利用锗掺杂磁控直拉单晶硅片机械强度较高的优点，可以降低太阳电池生产过程破损率.     

光致发光技术在Si基太阳电池缺陷检测中的应用

太阳电池的缺陷往往限制了其光电转化效率和使用寿命。利用光致发光原理获取晶体Si太阳电池的荧光照片,用以诊断其缺陷。外界的光能在Si中被吸收,产生非平衡少数载流子,而一部分载流子的复合是以发光形式来完成的。发出的光子可以被灵敏的CCD相机获得,得到太阳电池的辐射复合分布图像。这种光强分布反映出非平衡少数载流子的数目分布,裂痕和缺陷处表现为较低的光致发光强度。这里关注的是单晶Si太阳电池的检验。在室温条件下电池的裂痕和缺陷可以快速予以检测,验证了"光致发光效应"有潜力成为流水线式检测产品的手段。     

单晶硅太阳电池纳米减反射膜的研究

报道了用热喷涂工艺制备单晶硅太阳电池纳米减反射膜的研究结果 ,讨论了衬底温度对 Ti Ox 纳米减反射膜结构及折射率的影响 ,优化了热喷涂的工艺条件 ,并研究了 Ti Ox 纳米减反射膜对单体太阳电池效率的贡献。实验证明 ,用热喷涂工艺制备的纳米 Ti Ox 减反射膜可使 1 0 0 mm× 1 0 0 mm单体太阳电池的平均光电转换效率增加 8%～ 9%。     

纳米硅/晶体硅异质结电池的暗I-V特性和输运机制

采用HWCVD技术在P型CZ晶体硅衬底上制备了纳米硅／晶体硅异质结太阳电池,测量了晶体硅表面在不同氢处理时间下的异质结的暗I-V特性和相应的电池性能参数．室温下的正向暗I-V特性采用双二极管模型来拟合,可将0～1V的电压范围区分为4个区域：旁路电阻（0～0．15V）、非理想二极管2（0．15～0．3V）、理想二极管1（0．3～0．5V）和串联电阻（〉0．5V）．拟合结果表明,适当的氖处理时间（～30s）可有效降低非理想二极管的理想因子n2,即降低界面复合电流,表明具有好的界面特性．对于282～335K的暗I—V温度特性的研究表明,在0．15～0．3V的低电压范围,暗电流主要由耗尽区的复合电流提供,0．3～0．5V电压范围,对输运起主要作用的是隧穿过程,该过程可用通过界面陷阱能级的隧穿模型来解释．     

Passivation of a (100) Silicon Surface by Silicon Dioxide Grown in Nitric Acid

This letter investigates silicon dioxide layers grown at low temperature in concentrated nitric acid using a two-step process developed by Imai for thin-film transistors. With photoconductance measurements, we find that, prior to an anneal, nitric acid oxidation does not passivate the silicon surface, but, after a 30-min nitrogen anneal at 1100 $^{circ}hbox{C}$, a surface recombination velocity (SRV) of 107 cm/s (at $Delta n = hbox{10}^{15} hbox{cm}^{-3}$ ) is attained on 1-$Omegacdothbox{cm}$ n-type silicon. The SRV is further decreased to 42 cm/s after a 30-min forming gas anneal (FGA) at 400 $^{circ}hbox{C}$, which is equivalent to a thermal oxide under similar annealing conditions, although it is not stable and returns to its pre-FGA state over time. Capacitance–voltage and photoconductance measurements suggest that the oxides contain a high positive fixed charge—particularly after a 1100 $^{circ}hbox{C} hbox{N}_{2}$ anneal—which aids the passivation of n-type and intrinsic silicon but harms the passivation of low-resistivity p-type silicon.