索尼公司提出了新型双极结构

日本索尼公司采用发射极低浓度结构,研制出可望改变所有双极器件结构的技术。已往的发射区浓度较基区高几个量级,而发射极电流则几乎由发射极注入电流所组成。索尼公司提出的发射区浓度反而比基区低一至二个量级,且在发射区内有电势垒,这一势垒将来自基区的少子予以反射,不许其变成发射极电流成分。这种双极结构是N~+NPN,即发射极由N~+N组成,发射区N的浓度较P低一至二个量级。据称,这种技术的优点在于适合于大量生产,防止发射极陷落效应,发射极掺杂不影响基区浓度的再分布,可防     

背接触太阳电池发射区设计及可靠性研究

利用Silvaco-TCAD仿真软件全面系统地分析了不同发射区表面浓度和结深对n型插指背接触(IBC)太阳电池短路电流、开路电压、填充因子及转换效率的影响.借鉴双极半导体器件抗二次击穿技术,详细分析了不同发射区结深、发射区边缘刻蚀技术和发射区边缘选择性掺杂技术对IBC电池热击穿特性的影响.结果表明:发射区表面浓度越大、结深越深,IBC电池效率越高.当发射区表面浓度为5× 1020 cm-3、结深为1 μm时,转换效率高达23.35％.同时,深结发射区也有助于改善IBC电池的热击穿特性.发射区边缘刻蚀结构不具有改善IBC电池热击穿特性的作用,而发射区边缘选择性掺杂结构可有效改善IBC电池的热击穿特性,从而提高IBC太阳电池组件的可靠性.     

SOI MOSFET寄生双极晶体管效应的研究

研究了硅膜掺杂浓度,厚度和硅化物厚度等工艺条件对SOIMOSFET寄生双极晶体管增益的影响。提高体区掺杂浓度、增加硅膜和硅化物厚度能够减小增益。原因是：①基区杂质浓度增加,减弱了发射极向基区注人多子,增强了基区向发射区的少子注入;②增加硅化物厚度会增加其横向扩展,减小发射极的注入效率。     

陷阱分布模型对非晶Si太阳电池性能的影响

利用TCAD软件模拟分析了ITO/p-a-Si:H/i-a-Si:H/n-a-Si:H结构的非晶硅太阳电池的J-V特性,研究了不同缺陷分布模型对太阳电池光电特性的影响。利用一种较精确的陷阱模型优化了太阳电池的结构参数,重点研究了本征层厚度对太阳电池光电特性的影响。模拟实验表明,氢化非晶硅(a-Si:H)PIN结构太阳电池本征层厚度存在一个最佳区间,在该区间电池总体性能较为理想,包括对应的光电转换效率达到峰值。得到的a-Si:H太阳电池填充因子可达到约0.8,最高光电转换效率可达到约13%。     

陷阱分布模型对非晶Si太阳电池性能的影响

利用TCAD软件模拟分析了ITO/p-a-Si：H/i-a-Si：H/n-a-Si：H结构的非晶硅太阳电池的J-V特性,研究了不同缺陷分布模型对太阳电池光电特性的影响。利用一种较精确的陷阱模型优化了太阳电池的结构参数,重点研究了本征层厚度对太阳电池光电特性的影响。模拟实验表明,氢化非晶硅（a-Si：H）PIN结构太阳电池本征层厚度存在一个最佳区间,在该区间电池总体性能较为理想,包括对应的光电转换效率达到峰值。得到的a-Si：H太阳电池填充因子可达到约0.8,最高光电转换效率可达到约13%。     

InGaAsP/InP异质结双极晶体管的研究

用液相外延方法研制了InGaAsP/InP异质结双极晶体管(HBT),并研究了其直流特性。该HBT的发射区和集电区材料为InP(禁带宽度为1.35eV),基区材料为InGaAsP(禁带宽度0.95eV)。器件采用台面结构,发射结、集电结面积分别为5.0×10~(-5)cm~2、3.46×10~(-5)cm~2。基区宽度约为0.2μm,基区掺杂浓度为(2～3)×10~(17)/cm~3。在I_c=3～5mA,V_(ce)=5～10V时。共射极电流放大倍数达到30～760。符号表 q 电子电荷ε介电常数 k 玻耳兹曼常数 T 绝对温度β共射极电流放大倍数γ发射极注入效率 A_e 发射结面积 I_(ne) 发射极电子电流 I_(pe) 发射极空穴电流 I_(rb) 基区体内复合电流 I_(gre) 发射结空间电荷区产生-复合电流 I_(sb) 基区表面复合电流 I_(nc) 被集电极收集的电子电流 m_(pb)~* 基区中空穴有效质量 m_(?)~* 发射区电子有效质量 N_(Ab) 基区中受主掺杂浓度 N_(D(?)) 发射区施主掺杂浓度 N_(D(?)) 集电区施主掺杂浓度 W_b 基区宽度 L_(ab) 基区中电子扩散长度μ_(ab) 基区中电子迁移率τ_(ab) 基区中电子寿命 V_(no) 从发射区注入到基区电子的平均速度 V_(p(?)) 从基区注入到发射区空穴的平均速度△E_g 发射区与基区的禁带宽度差△E_c 异质结交界面导带不连续量△E_v 异质结交界面价带不连续量。且有:△E_c+△E_v=△E_g A_(?) 基区表面有效复合面积     

机电部十三所用MOCVD GaAlAs/GaAs材料做出HBT

<正> 利用宽禁带发射极高注入效率的异质结双极晶体管(HBT),可同时提高基区掺杂、降低发射区掺杂,从而降低基区电阻和基极-发射极结电容。由于HBT在高频高速运用中具有极大潜力,使HBT的研究成为国际上的一个活跃课题。该器件要求精确控制极薄的多层外延结构材料的组分和掺杂浓度、以及精细的器件横向尺寸,从而在工艺上具有相当的难度。机电部十三所于1988年十月在国内首次使用MOCVD生长的GaAlAs/GaAs异质结多层结构材料,成功地研制出HBT。其材料结构为:衬底:N~+-GaAs;     

工业级纳米绒面多晶硅太阳电池的发射极扩散方阻调控其光电转换性能研究

本文制备了工业级纳米绒面多晶硅太阳电池,研究 了发射极扩散方阻对其光电转换 性能的影响。结果表明:提高发射极扩散方阻能够有效地提升电池的开路电压、短路电流, 但填充因子相对降低。通过分析关键光电参数,其原因归结为:提高发射极扩散方阻有利于 降低发射极及其表面载流子复合,但过高的发射极扩散方阻将导致发射极与金属栅线接触不 良。采用优化的发射极扩散方阻,纳米绒面相对于微米绒面多晶硅太阳电池具有改善的光电 转换性能,产线均值光电转换效率达到了19.20%。基于上述研究结果 ,讨论了进一步通过调控发射极扩散方阻来优化纳米绒面多晶硅太阳电池的方法。     

n型异质结背接触太阳电池前表面的场钝化

利用Silvaco-TCAD仿真软件建立二维模型,对n型异质结背接触(HBC)单晶硅太阳电池前表面场进行模拟研究。通过在n型单晶硅衬底正面分别引入一层较薄的本征非晶硅层和一层n+非晶硅层对电池前表面进行高质量的场钝化,分析了n+非晶硅层的厚度和掺杂浓度以及本征非晶硅层的厚度和带隙宽度对电池电学性能的影响。模拟结果表明:当n+非晶硅层厚度小于6 nm,掺杂浓度为1×1019 cm-3,本征非晶硅层的厚度为3 nm,带隙宽度大于1.5 eV时,电池前表面实现了良好的场钝化效果,HBC太阳电池获得了24.5%的转换效率。     

梯度掺杂对β-FeSi2(n)/c-Si(p)太阳能电池转化效率的影响

用AFORS-HET软件对β-FeSi2(n)/c-Si(p)太阳能电池的发射层进行了梯度掺杂模拟,并研究了发射区掺杂总量相同时梯度掺杂和均匀掺杂对电池转化效率的影响。分别讨论了梯度掺杂时发射区的能带、发射区的浓度差、发射区的层数对电池转化效率的影响。实验结果表明,发射区梯度掺杂可以明显提高电池转化的效率。随着发射区各层浓度比的增大,电池转化效率先增大后保持不变;随着发射区层数的增加,电池转化效率先增大后保持不变;随着发射区厚度的增加,电池转化效率逐渐降低。梯度掺杂电池转化效率的提高总量远大于因梯度发射区过厚造成的电池转化效率的降低总量。     

Optimization of ultraviolet laser doping for crystalline silicon solar cells with a novel segmented selective emitter design

This paper reports on the use of ultraviolet laser for forming segmented selective emitters on POCl ₃ n ⁺ –p–p ⁺ solar cells. Laser scan speed, pulse power, and repetition rate are optimized to minimize laser‐induced defects, which are found to enhance recombination and reduce the local open‐circuit voltage. Laser‐doped selective emitters formed by locally driving in additional phosphorous from the diffusion glass are well suited for an etchback process without the need for a mask. In this paper, we show a novel selective emitter design that is segmented instead of continuous, combined with an emitter etchback process gives an efficiency improvement of about 0.3% absolute over a standard industrial type solar cell and 0.2% absolute improvement over a non‐segmented selective emitter solar cell. Copyright © 2012 John Wiley & Sons, Ltd.     

A Novel Silicon Photovoltaic Cell Using a Low-Temperature Quasi-Epitaxial Silicon Emitter

A new silicon solar cell fabricated using a low-temperature process is demonstrated with a highly conductive (n+) quasi-epitaxial (qEpi-Si) silicon emitter deposited on silicon substrates, without using transparent conductive oxides. The emitter was formed by a plasma-enhanced chemical vapor deposition process on granular multicrystalline silicon (mc-Si) substrates at a substrate temperature of 250 . The new qEpi-Si/(p)mc-Si junction was found to be of good quality for photovoltaic applications. Solar cells of 1- area and conversion efficiencies exceeding 10% have been fabricated in a simple fabrication process and device structure.     

Co‐optimization of emitter profile and metal grid of selective emitter silicon solar cells

Co‐optimization of the metallization and emitter dopant profile is fully investigated for selective emitter crystalline silicon solar cells. The simulation parameters for the laser doping selective emitter, metallization by plating, silicon nitride passivation, and aluminum back surface field are identified and reached. Internal light flux reflection is also considered in the model. In particular, the influence of the increased light trapping ability of a textured surface on the optimization results is clarified by comparing a cell with a non‐textured surface. In this paper, the optimization results, including the electrical performances of a solar cell are discussed in detail. On the basis of these simulation results, an optimized metallization and emitter dopant profile is proposed. Copyright © 2011 John Wiley & Sons, Ltd.     

Low-cost back contact silicon solar cells

Back-contacted solar cells offer multiple advantages in regard of reducing module assembling costs and avoiding grid shadowing losses. The investigated emitter-wrap-through (EWT) device design has an electrical connection of the front emitter and the rear emitter grid in form of small holes drilled into the crystalline silicon wafer. The obtained cell structure is especially suitable for low-cost base material with small minority carrier diffusion lengths. Different industrially applicable solar cell manufacturing processes for EWT devices are described and compared. The latest experimental results are presented and interpreted; the photocurrent is found to be distinctly increased. The relation between open circuit voltage and rear side passivation is discussed based on two-dimensional (2-D) computer simulations     

Numerical simulations of buried emitter back‐junction solar cells

We recently introduced the buried emitter back‐junction solar cell, featuring large area fractions of overlap between n⁺‐type and p⁺‐type regions at the rear side of the device. In this paper we analyse the performance of the buried emitter solar cell (BESC) and its generalisations by one‐dimensional device simulations and analytical model calculations. A key finding is that the generalised versions of the BESC structure allows achieving very high efficiencies by passivating virtually the entire surface of p‐type emitters by an oxidised n‐type surface layer. A disadvantage of this type of full‐area emitter passivation in the generalised back‐junction BESC is the need for an insulating layer between the metallisation of the emitter and the contact to the base, which is technologically difficult to achieve. Copyright © 2009 John Wiley & Sons, Ltd.     

一种新的测量硅太阳电池前电极穿透p-n结所引起的漏电电阻率的方法

漏电电阻可以大幅度地降低太阳电池的转换效率,目前对它的测量一般是电池中所有的漏电所造成的总效果。为了测得太阳电池前电极穿透发射区所引起的漏电电阻值,本文制备了一种具有梁桥电极的新型结构太阳电池。结果表明,电池前电极穿透发射区所引起的漏电电阻率值比其他发射区域的漏电要严重的多。这些样品制备有与生产工艺兼容的特点,同时使用它能够为电池结构、材料组成和工艺参数提供许多有用的信息。     

Determination of the maximum efficiency solar cell structure

A very general formulation of a semiconducting photovoltaic device is given. The efficiency of this device is maximized with respect to tis structural parameters. In this way it is shown that no solar cell structure can achieve a large efficiency than an infinite tandem cell, with bandgaps monotonically decreasing from infinity to zero, and of which each individual cell is a selective black body with its own appropriate bias voltage. This maximum efficiency is numerically calculated for various cell- and sun temperatures and concentration factors.     

高方块电阻发射区单晶硅太阳电池的性能优化

通过提高发射区的方块电阻和优化发射区的磷杂质浓度纵向分布,制备了性能优良的单晶硅太阳电池。I-V测量分析表明:高表面活性磷杂质浓度浅结发射区太阳电池短路电流密度、开路电压和填充因子分别提高了0.32mA/cm2,1.19mV和0.22%,因此转换效率提高了0.22%。内量子效率分析表明:高表面活性磷杂质浓度浅结发射区太阳电池短路电流密度的提高是由于短波光谱响应增强了。SEM分析表明:高表面活性磷杂质浓度浅结发射区太阳电池在发射区硅表面沉积的Ag晶粒分布数量更多、一致性更好,从而更容易收集光生电流传输到Ag栅线,改善了太阳电池的性能。     

Role of front contact work function on amorphous silicon/crystalline silicon heterojunction solar cell performance

We investigated with numerical simulations the effects that a transparent conductive oxide front contact (TCO) can have on amorphous silicon/crystalline silicon heterojunction solar cells. We found that, due to the extremely thin emitter layer used in this kind of device, the built-in potential available cannot be merely defined by the difference between the work function of the emitter and the base, but it depends on TCO work function as well. As a consequence, because of the correlation between built-in potential and open circuit voltage, the TCO work function strongly affects the solar cell performance. Simulation results show that a higher work function leads to the best device efficiency.     

Thin Al2O3 passivated boron emitter of n‐type bifacial c‐Si solar cells with industrial process

We have presented thin Al₂O₃ (~4 nm) with SiN_x:H capped (~75 nm) films to effectively passivate the boron‐doped p⁺ emitter surfaces of the n‐type bifacial c‐Si solar cells with BBr₃ diffusion emitter and phosphorus ion‐implanted back surface field. The thin Al₂O₃ capped with SiN_x:H structure not only possesses the excellent field effect and chemical passivation, but also establishes a simple cell structure fully compatible with the existing production lines and processes for the low‐cost n‐type bifacial c‐Si solar cell industrialization. We have successfully achieved the large area (238.95 cm²) high efficiency of 20.89% (front) and 18.45% (rear) n‐type bifacial c‐Si solar cells by optimizing the peak sintering temperature and fine finger double printing technology. We have further shown that the conversion efficiency of the n‐type bifacial c‐Si solar cells can be improved to be over 21.3% by taking a reasonable high emitter sheet resistance. Copyright © 2017 John Wiley & Sons, Ltd.