弱硼掺杂补偿对氢化微晶硅薄膜制备与特性的影响

研究了弱硼掺杂补偿对甚高频等离子体增强化学气相沉积方法生长氢化微晶硅薄膜(μc-Si:H)及材料特性的影响.实验发现,随着弱硼补偿剂量的增大,μc-Si:H薄膜的沉积速率先减小后增加,变化范围约为0.7～0.8nm/s.相比较而言,材料的结晶度以及晶粒的平均颗粒尺寸则呈现出先增后减的变化,且变化的幅度较大,当弱硼补偿剂量大于2.5ppm时,过度的弱硼补偿将导致μc-Si:H薄膜的结晶状况恶化.此外,光敏性、暗电导及电导激活能的测量结果进一步表明,弱硼补偿显著影响μc-Si:H薄膜的光电特性,弱硼补偿剂量为2.5ppm左右时,材料的光电特性最为理想.因此,优化弱硼补偿剂量是获得器件级质量μc-Si:H材料的有效途径.     

弱硼掺杂补偿对氢化微晶硅薄膜制备与特性的影响

研究了弱硼掺杂补偿对甚高频等离子体增强化学气相沉积方法生长氢化微晶硅薄膜（μc-Si∶H）及材料特性的影响.实验发现,随着弱硼补偿剂量的增大,μc-Si∶H薄膜的沉积速率先减小后增加,变化范围约为0.7～0.8nm/s.相比较而言,材料的结晶度以及晶粒的平均颗粒尺寸则呈现出先增后减的变化,且变化的幅度较大,当弱硼补偿剂量大于2.5ppm时,过度的弱硼补偿将导致μc-Si∶H薄膜的结晶状况恶化.此外,光敏性、暗电导及电导激活能的测量结果进一步表明,弱硼补偿显著影响μc-Si∶H薄膜的光电特性,弱硼补偿剂量为2.5ppm左右时,材料的光电特性最为理想.因此,优化弱硼补偿剂量是获得器件级质量μc-Si∶H材料的有效途径.     

硼掺杂比对p型微晶硅薄膜生长特性的影响

采用射频等离子体增强化学气相沉积法制备了硼不同掺杂比系列的p型微晶硅薄膜。采用光发射谱仪对薄膜的沉积过程进行了原位表征,采用喇曼光谱和椭圆偏振光谱仪对薄膜的结构及性能进行了分析。结果表明:随着硼掺杂比的增加,SiH*,Hα和Hβ的发射峰强度都呈现出先快速减小然后达到稳定状态的特点。在硼小剂量掺杂时,硼的催化作用促进了薄膜的晶化;但是随着硼掺杂比的进一步增加,薄膜的晶化率下降。在薄膜生长过程中,薄膜的沉积速率和生长指数β均随掺杂比的增加而增加,这主要是因为硼不仅促进了薄膜生长还加速了薄膜的粗糙化。     

PECVD法制备的ZnO薄膜结晶性能的影响

报道了在等离子体作用下,以CO2/H2为氧源,Zn(C2H5)2为锌源,N2为载气,在Si(111)衬底上采用自行设计等离子体化学气相沉积(PECVD)装置来生长的ZnO薄膜。采用X射线衍射仪(XRD)、原子力显微镜(AFM)和场发射扫描电镜分别对不同衬底温度生长的薄膜样品进行了组成、表面和横截面的形貌表征,并且测试了薄膜的PL谱。研究结果表明,衬底温度直接影响薄膜的结晶质量。随衬底温度的升高,ZnO薄膜的结晶取向性开始增强,晶粒尺寸增大。在衬底温度约为450℃时,生长的ZnO薄膜有很强的择优取向性。     

掺杂室沉积本征微晶硅材料及其在太阳能电池中的应用

在掺杂P室采用甚高频等离子体增强化学气相沉积(VHF-PECVD)技术,制备了不同硅烷浓度条件下的本征微晶硅薄膜.对薄膜电学特性和结构特性的测试结果分析表明:随硅烷浓度的增加,材料的光敏性先略微降低后提高,而晶化率的变化趋势与之相反;X射线衍射(XRD)测试表明材料具有(220)择优晶向.在P腔室中用VHF-PECVD方法制备单结微晶硅太阳能电池的i层和p层,其光电转换效率为4.7%,非晶硅/微晶硅叠层电池(底电池的p层和i层在P室沉积)的效率达8.5%.     

掺杂室沉积本征微晶硅材料及其在太阳能电池中的应用

在掺杂P室采用甚高频等离子体增强化学气相沉积（VHF—PECVD）技术,制备了不同硅烷浓度条件下的本征微晶硅薄膜．对薄膜电学特性和结构特性的测试结果分析表明：随硅烷浓度的增加,材料的光敏性先略微降低后提高,而晶化率的变化趋势与之相反;X射线衍射（xRD）测试表明材料具有（220）择优晶向．在P腔室中用VHF—PECVD方法制备单结微晶硅太阳能电池的i层和p层,其光电转换效率为4．7％,非晶硅／微晶硅叠层电池（底电池的p层和i层在P室沉积）的效率达8．5％．     

纳米硅薄膜的特点及其制备技术

作为一项新一半导体薄膜技术，阐明了纳米硅薄膜的若干重要特点；着重讨论了利用等离子体增强化学气相淀积技术制备纳米硅薄膜的试验参数选择。     

PECVD法低温沉积多晶硅薄膜的研究

在玻璃衬底上采用常规的PKCVD法在低温(≤400℃)条件下制得大颗较(直径＞100nm)、择优取向(220)明显的多晶硅薄膜。选用的反应气体为SiF4和H2混合气体。加入少量的SiH4后，沉积速率提高了近10倍。分析认为，在低温时促使多晶硅结构形成的反应基元应是SiFmHn(m n≤3)，而不可能是SiHn(n≤3)基团。     

异质结硅太阳能电池a—Si：H薄膜的研究

通过应用Scharfetter-Gummel数值求解Poisson方程，对热平衡态P^ （a-Si:H)/n(c-Si)异质结太阳能电池进行计算机数值模拟分析。结果指出，采用更薄P^ (a-Si：H）薄膜设计能有效增强光生载流子的传输与收集，从而提高a-Si/c-Si异质结太阳能电池的性能。同时，还讨论了P^ (a-Si:h)薄膜中P型掺杂浓度对光生载流了传输与收集的影响。高强茺光照射下模拟，计算表明，a-Si/c-Si异质结结构太阳能电池具有较高光稳定性。     

掺硼非晶硅薄膜的电阻不稳定性研究

以硅烷和硼烷为气相反应气体,采用等离子体增强化学气相沉积法(PECVD)制备了硼掺杂氢化非晶硅薄膜.测试了不同样品电阻随测试时间的变化,以及光照和噪声对材料电学性质的影响.结果表明,刚制备出来的样品存在氧化现象,长时间光照会出现S-W效应,由于RTS噪声的存在,样品电阻会出现随机性波动.     

Boron-doped silicon film as a recombination layer in the tunnel junction of a tandem solar cell

Boron-doped hydrogenated silicon films with different gaseous doping ratios (B2H6/SiH4) were deposited in a plasma-enhanced chemical vapor deposition (PECVD) system. The microstructure of the films was investigated by atomic force microscopy (AFM) and Raman scattering spectroscopy. The electrical properties of the films were characterized by their room temperature electrical conductivity (σ) and the activation energy (Ea). The results show that with an increasing gaseous doping ratio, the silicon films transfer from a microcrystalline to an amorphous phase, and corresponding changes in the electrical properties were observed. The thin boron-doped silicon layers were fabricated as recombination layers in tunnel junctions. The measurements of the Ⅰ-Ⅴ characteristics and the transparency spectra of the junctions indicate that the best gaseous doping ratio of the recombination layer is 0.04, and the film deposited under that condition is amorphous silicon with a small amount of crystallites embedded in it. The junction with such a recombination layer has a small resistance, a nearly ohmic contact, and a negligible optical absorption.     

四结叠层太阳电池中AlGaAs/GaAs隧穿结的特性和表现

III-V族化合物叠层太阳电池是具有超高转换效率的第三代新型太阳电池。四结叠层电池GaInP/GaAs/InGaAs/Ge,各子电池的带隙分别为1.8, 1.4, 1.0, 0.7(ev)。为了使各子电池之间电流匹配,在各子电池之间以隧穿结互相连接。本文主要探索研究了四结叠层电池GaInP/GaAs/InGaAs/Ge隧穿结的特性,三个隧穿结的材料选取,探讨了隧穿结对整体叠层电池的特性的补偿作用,对各子电池电流密度的影响,以及在此基础上对整体电池效率的增加。选用AlGaAs/GaAs作为隧穿结运用PC1D进行电池的整体模拟仿真,得到各子电池电流密度分别为16.02mA/cm²,17.12 mA/cm²,17.75 mA/cm²,17.45 mA/cm²,电池在AM0下的开路电压Voc为3.246V,转换效率为33.9%。     

High efficiency triple junction thin film silicon solar cells with optimized electrical structure

We report on improving the performance of pin‐type a‐Si:H/a‐SiGe:H/µc‐Si:H triple‐junction solar cells and corresponding single‐junction solar cells in this paper. Based on wet‐etching sputtered aluminum‐doped zinc oxide (ZnO:Al) substrates with optimized surface morphologies and photo‐electrical material properties, after adjusting individual single‐junction solar cells utilized in triple‐junction solar cells with various optimization techniques, we pay close attention to the optimization of tunnel recombination junctions (TRJs). By means of the optimization of individual a‐Si:H/a‐SiGe:H and a‐SiGe:H/µc‐Si:H double‐junction solar cells, we compensated for the open circuit voltage (V_oc) loss at the a‐Si:H/a‐SiGe:H TRJ by adopting a p‐type µc‐Si:H layer with a low activation energy. By combining the optimized single‐junction solar cells and top/middle, middle/bottom TRJs with little electrical losses, an initial efficiency of 15.06% was achieved for pin‐type a‐Si:H/a‐SiGe:H/µc‐Si:H triple‐junction solar cells. Copyright © 2014 John Wiley & Sons, Ltd.     

AlGaAs/GaAs tunnel junctions in a 4-J tandem solar cell

TheⅢ-Ⅴcompound tandem solar cell is a third-generation new style solar cell with ultra-high efficiency. The energy band gaps of the sub-cells in a GaInP/GaAs/InGaAs/Ge 4-J tandem solar cell are 1.8,1.4,1.0 and 0.7 eV,respectively.In order to match the currents between sub-cells,tunnel junctions are used to connect the sub-cells.The characteristics of the tunnel junction,the material used in the tunnel junction,the compensation of the tunnel junction to the overall cell’s characteristics,the tunnel junction’s influence on the current density of sub-cells and the efficiency increase are discussed in the paper.An AlGaAs/GaAs tunnel junction is selected to simulate the cell’s overall characteristics by PC1D,current densities of 16.02,17.12,17.75 and 17.45 mA/cm² are observed,with a V_oc of 3.246 V,the energy conversion efficiency under AM0 is 33.9%.     

Numerical simulation of tunnel diodes for multi‐junction solar cells

This work presents efforts to simulate numerically the current voltage (IV) curve of a III–V based Esaki tunnel diode. Using a tunneling model, which takes into account the full nonlocality of the barrier, a good agreement between measured and simulated IV curves of a GaAs tunnel diode was achieved. The influence of a series resistance effect as well as the importance of trap assisted tunneling (TAT) could be shown. In addition, we present a two‐dimensional model of a III–V multi‐junction solar cell including the numerical model of the investigated Esaki tunnel diode. Copyright © 2008 John Wiley & Sons, Ltd.     

应用于太阳能电池的氢化非晶亚氧化硅的退火优化

在此篇文章中,开发出了适用于工业化生产的氢化非晶亚氧化硅(a-SiOx:H)作为太阳能电池的钝化层的工艺方法。a-SiOx:H钝化层使用PECVD方法,在大概250℃条件下生长,气体由一氧化氮、氦气和硅烷组成。我们又进一步研究了退火对少数载流子寿命和表面复合速率的影响,因为其对太阳能电池的最终效率影响很大。在4•Ω•cm,P型FZ硅片上测试,少数载流子寿命在退火前只有270us,在退火之后可以达到670us,相应的表面复合速率从70 cm/s 降到30 cm/s。光学特性分析发现,和在太阳能电池中经常使用的本征非晶硅钝化层相比,a-SiOx:H在蓝光附近的光的吸收率有很大的下降。本文引入制作a-SiOx:H钝化层的方法成本低、质量高,适合于工业化生产。     

Modeling the potential of screen printed front junction CZ silicon solar cell with tunnel oxide passivated back contact

Carrier selective passivated contacts composed of thin oxide, n + polycrystalline Si and metal on top of a n‐Si absorber can significantly lower the recombination current density (J_orear ≤8 fA/cm²) under the contact while providing excellent specific contact resistance (5–10 mΩ‐cm²); 25.1% efficient small area cells with photolithography front contacts on boron doped selective emitter and Fz wafers have been achieved by Fraunhofer ISE using their tunnel oxide passivated contact (TOPCon) approach. This paper shows a methodology to model such passivated contact cells using Sentaurus device model, which involves replacing the TOPCon region by carrier selective electron and hole recombination velocities to match the measured J_orear of the TOPCon region as well as all the light IV values of the cell. We first validated the methodology by modeling a 24.9% reference cell. The model was then extended to assess the efficiency potential of large area TOPCon cells on commercial grade n‐type Cz material with screen‐printed front contacts. To use realistic input parameters, a 21% n‐type PERT cell was fabricated on Cz wafer (5 Ω‐cm, 1.5‐ms lifetime). Modeling showed that the cell efficiency will improve to only 21.6% if the back of this cell is replaced by the above TOPCon, and the performance is limited by the homogenous emitter. Efficiency was then modeled to improve to 22.6% with the implementation of selective emitter (150/20 Ω/sq). Finally, it is shown that screen printing of 40‐µm‐wide lines and improved bulk material (10 Ω‐cm, 3‐ms lifetime) can raise the single side TOPCon Cz cell efficiency to 23.2%. Copyright © 2016 John Wiley & Sons, Ltd.     

MOS隧道结的光发射

介绍了一种新型的半导体电致发光器件并讨论了提高其发射效率所采取的措施     

High‐rate deposition of microcrystalline silicon in a large‐area PECVD reactor and integration in tandem solar cells

We study the high‐rate deposition of microcrystalline silicon in a large‐area plasma‐enhanced chemical‐vapor‐deposition (PECVD) reactor operated at 40.68 MHz, in the little‐explored process conditions of high‐pressure and high‐silane concentration and depletion. Due to the long gas residence time in this process, the silane gas is efficiently depleted using moderate feed‐in power density, thus facilitating up‐scaling of the process to large surfaces. As observed in more traditional deposition processes, the deposition rate and performance of device‐quality material are limited by the inter‐electrode gap of the reactor. We significantly increase the cell performances by reducing this gap. X‐ray diffractometry (XRD) and secondary ion mass spectroscopy (SIMS) are used to characterize the microcrystalline material deposited in the modified reactor at a rate of 1 nm/s. Comparison with a microcrystalline process at a low deposition rate demonstrates that the crystallographic orientation of the absorbing layer of the cell and the concentrations of contaminants are strongly correlated and dependent on the process. We use microcrystalline cells with absorber layer grown at a rate of 1 nm/s integrated as bottom cells in amorphous‐microcrystalline (micromorph) tandem solar cells using the superstrate configuration. We report an initial efficiency of 10.8% (9.6% stabilized) for a tandem cell with 1.2 cm² surface. Copyright © 2010 John Wiley & Sons, Ltd.     

Base doping and recombination activity of impurities in crystalline silicon solar cells

The optimisation of base doping for industrial crystalline silicon solar cells is examined with model calculations. Focus is on the relation between base doping and carrier recombination through the important impurities interstitial iron (Fe_i) and the metastable boron–oxygen (BO) complex. In p‐type silicon, the optimum base resistivity is strongly dependent on defect concentration. In n‐type silicon, recombination due to Fe_i is much lower and nearly independent of resistivity. Fe_i is likely representative for other transition metal impurities. In many real cells a balance between Fe_i or similar defects, and BO will occur. Copyright © 2004 John Wiley & Sons, Ltd.