Direct-PECVD a-SiOx:H/a-SiNx:H 叠层系统对多晶硅电池的钝化研究

本文中应用全部PECVD工艺沉积a-SiOx:H、a-SiNx:H,和a-SiOx:H/a-SiNx:H叠层系统,比较了不同钝化膜对多晶硅太阳能电池发射极和背面钝化效果,应用FGA、RTP等热处理方法对钝化膜进行处理,重点讨论了FGA(Forming gas annealing)温度和时间的长短对钝化的影响.结果表明:低温FGA对只有单面钝化膜的硅片钝化效果不明显,而在800 ℃下FGA有明显作用,而且钝化效果随着时间的增加呈现出先增大后减小然后再增大的现象;退火后降温环境中是否有H和降温时间对钝化效果有很大的影响,但是对于双面膜无论FGA温度高低对钝化都有帮助,文中对上述现象做了合理的解释.最后利用双面叠层钝化膜经过FGA处理后得到的多晶硅片的少子寿命达到14.2 μs,比镀膜之前的3.0 μs提高了11.2 μs,使多晶硅太阳能电池暗电压 Voc达到630 mV.     

从P-a-SiC:H到P-μc-Si:H过程中材料特性的变化

采用RF-PECVD方法,在P-a-SiC:H薄膜沉积技术基础上,通过逐步减小碳、硼的掺杂浓度,增大氢稀释率,使材料从非晶态向微晶态转变,在获得本征微晶材料之后,再逐步增大硼掺杂浓度,得到P型微晶硅薄膜材料(暗电导率为5.22×10-3S/cm,光学带隙大于2.0eV).在这个过程中可以明显观察到碳、硼抑制材料晶化的作用.     

Variation of the defect density in a-Si:H and μc-Si:H based solar cells with 2 MeV electron bombardment

Improvement of the performance of solar cells based on amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon requires understanding of the role of the deep defects – dangling bonds – in the bulk of the intrinsic a-Si:H or μc-Si:H absorber layers. A straightforward way to understand how these defects may affect the performance of the cells is to investigate changes in the device performance upon variation in the defect density.In the present work solar cells with a-Si:H and μc-Si:H absorber layers were exposed to 2 MeV electron bombardment. The performance of the cells after various bombardment doses and annealing steps was evaluated in view of the changes in the defect density of intrinsic layers, measured with ESR on nominally identical absorber layers irradiated in parallel with the cells.The defect density was varied over a range of 2 orders of magnitude. In the solar cells a strong degradation of performance is observed upon irradiation with the biggest effect on the short circuit current density J_SC for both types of absorber layers. In most cases both V_OC and J_SC recover after the final annealing step (at 160 °C) for both types of cells.     

掺磷nc-Si:H薄膜的微结构与光电特性

采用常规射频等离子体增强化学气相沉积方法,以高氢稀释的SiH4为源气体和以PH3为掺杂剂,制备了磷掺杂的氢化纳米晶硅薄膜.结果表明,薄膜的生长速率随PH3/SiH4流量比(Cp)增加而显著减小.Raman谱的研究证实,随CP增加,薄膜的晶化率经历了先增大后减小的过程,当C,=1.0;,晶化率达到最大值45.9;.傅里叶变换红外吸收谱测量结果显示,薄膜中的H含量在CP=2.0;时达到最低值9.5;.光学测量结果表明,本征和掺P的氢化纳米晶硅薄膜在可见光谱范围呈现出良好的光吸收特性,在0.8 ～3.0 eV范围内,nc-Si (P):H薄膜的吸收系数显著大于c-Si.和α-Si:H薄膜相比,虽然短波范围的吸收系数较低,但是在hv＜1.7 eV区域,nc-Si(P):H薄膜的吸收系数要高两到三个量级,显示出优良的红光响应.电学测量表明,适当掺P会显著提高氢化纳米晶硅薄膜的暗电导率,当CP=0.5;时,薄膜的暗电导率可达5.4S·cm-1.     

透明导电薄膜与p-Si:H膜接触特性的研究

本实验采用PECVD方法在不同透明导电薄膜上沉积了p型掺杂(p-Si:H)膜.用拉曼(Raman)光谱测试了p-Si:H膜的晶化率,并用扫描电子显微镜(SEM)观察了其形貌.结果表明:在SnO2上沉积的p-Si:H膜的晶化率较其它两种衬底高,相应的SEM形貌显示颗粒尺寸也较大.通过I-V测试仪测试了ZnO:Al/p-Si:H、SnO2/p-Si:H和SnO2/ZnO:Al/p-Si:H的接触特性,结果显示ZnO:Al/p-Si:H的接触特性并不比SnO2/p-Si:H差.     

Fabrication and optimization of single-junction nc-Si:H n–i–p solar cells using Si:H phase diagram concepts developed by real time spectroscopic ellipsometry

In this study, we have developed and applied deposition phase diagrams in the plane of the bulk layer thickness d_b and the H₂-dilution ratio R = [H₂]/[Si₂H₆] for Si:H materials deposited by 70 MHz VHF PECVD from [H₂] + [Si₂H₆] mixed gases on c-Si/(native-oxide)/n-layer substrates. To establish the phase diagrams, series of Si:H depositions having different R values over the range of 60–150 were measured in real time using a rotating-compensator multichannel ellipsometer. Using phase diagram concepts for guidance, we have fabricated high efficiency single-junction nc-Si:H n–i–p solar cells with ～3 Å/s intrinsic layers using the VHF PECVD process. We have found that the nc-Si:H solar cells with the best performance are obtained by incorporating i-layers deposited in the single-phase nanocrystalline silicon regime near the transition boundary to mixed-phase (a + nc)-Si:H. Applying insights from real time spectroscopic ellipsometry moreover, we have investigated in detail the effects of the phase of the underlying n-layer on the phase evolution of the overdeposited Si:H i-layer and on the overall device performance. With the strategy developed here, a stabilized efficiency of η = 9.46% (V_oc = 0.516 V, J_sc = 24.65 mA/cm², FF = 0.744) has been achieved for nc-Si:H solar cells (0.25 cm² in active area) fabricated with an i-layer deposition rate of ～2.2 Å/s.     

PECVD a-Sic:H Young’s modulus obtained by MEMS resonant frequency

In this paper we study the Young’s modulus of PECVD obtained silicon rich (x > 0.5) a-Si_xC_1?x:H thin films through the study of the resonance frequency of free standing cantilevers. These structures are fabricated based on front side bulk micromachining of Si substrate and actuated thermally. In this approach, an alternating electric current passes through a photolithography patterned metallic film deposited on the cantilever, heating the structure by Joule effect and inducing vibrations on the cantilever. This method of actuation is independent of the separation between the structure and substrate, which is its main advantage, because it allows the actuation of cantilevers that are bent upwards or downwards, which is an aspect of particular importance in the characterization of PECVD materials for MEMS applications. The work is focused on low stress silicon rich amorphous hydrogenated silicon carbide films obtained by PECVD at low temperatures (320 °C). The measurements were carried out in groups of cantilevers with different length (between 550 and 200 μm) and utilizing a-SiC:H films obtained with three different compositions. The results show that the films exhibit modulus of elasticity in the range of 20–35 GPa, low residual stress (～90 GPa) and maintain excellent chemical inertness in KOH and HF solutions.     

Short H· · ·H distances in norbornene derivatives

A short H···H intramolecular interaction was reported previously for an anhydride of syn-sesquinorbornene. The synthesis and structure of a such an anhydride with an additional five-membered dithiole ring has been investigated. While hydrogen atom positions are not accurately located, the 1.62 Å separation indicates this molecule is a candidate for the shortest H···H interaction. Two cycloadducts of norbornadiene, which literature suggests might exhibit additional short interactions, are reported also; however, the isomers with minimal intramolecular interactions are the isolated products. C₂₂H₂₀O₃S₂, 3, crystallizes in P with a = 10.881(4), b = 13.712(8), C = 6.548(8) Å, = 101.32(6), = 107.49(5), = 90.49(4)°, D _calc = 1.445 g cm^–3, and Z = 2, C₂₁H₂₀O₄Cl₈, 5, in P2₁/n with a = 8.168(2), b = 13.488(4), c = 23.500(6) Å, = 94.72(2)°, D _calc = 1.597 g cm^–3, and Z = 4, C₂₁H₂₈O₄, 6, in P> with a = 12.667(2), b = 12.792(2), c = 12.540(2) Å, = 113.51(1), = 98.18(1), = 74.39(1)°, D _calc = 1.276 g cm^–3, and Z = 4.     

Synthesis and structure determination of a new layered zincophosphate: [H2N2C6H16]0.5[Zn2(PO4)(HPO4)(H2O)]·H2O

The synthesis and crystal structure of a new microporous zincophosphate are described. [H₂N₂C₆H₁₆]_0.5[Zn₂(PO₄)(HPO₄)(H₂O)]·H₂O crystallizes in the triclinic space group P1¯ with a = 8.822(4), b = 9.236(4), c = 8.451(3) Å, = 67.19(3), = 91.32(3), = 111.10(3)°, V = 586.7(4) ų and Z = 2. This new material consists of infinite two-dimensional anionic layers alternated with planes containing organic diprotonated templates, N, N, N, N-tetramethylethylenediamine [H₂N₂C₆H₁₆]²⁺ molecules. The framework structure is built up of ZnO₄, ZnO₃OH₂, PO₄, and PO₃OH tetrahedra, linked through oxygen vertices. The presence of terminal OH₂ and OH groups, leads to an open structure containing four- and eight-rings. The organic molecules are interconnected to the framework through hydrogen bonds.     

硼掺杂对μc-Si:H薄膜微结构和光电性能的影响

采用射频等离子增强化学气相沉积(RF-PECVD)法制备了掺硼氢化微晶硅(μc-Si:H)薄膜,研究了硼掺杂对薄膜的结晶状况、沉积速率、暗电导率和光学带隙的影响.拉曼光谱、扫描电子显微镜、分光光度计和电导率测试结果表明:当掺硼比(B2H6/SiH4)由0.1;增加到0.75;时,硅膜的晶化率逐渐降低,并由微晶向非晶过渡;沉积速率随掺硼比的增加线性增大;暗电导率先升高后下降,当掺硼比为0.5;时,暗电导率最大;光学带隙随掺硼比的增加逐渐减小.     

MWECR CVD法高速沉积α-Si:H薄膜的红外光谱研究

应用微波电子回旋共振化学气相沉积(MWECR CVD)方法,在较高速度下沉积了α-Si:H薄膜,用FTIR红外谱仪研究了α-Si:H薄膜的结构特性随H2/SiH4、沉积温度和沉积速率变化关系,并对2000cm-1附近的特征吸收峰用高斯函数进行了拟合分析,获得了沉积高质量α-Si:H薄膜的最佳工艺条件.     

辉光功率对n型a-Si:H薄膜结构及性能的影响

采用射频等离子增强化学气相沉积(RF-PECVD)方法,以氢稀释的硅烷(SiH4)为反应气体,磷烷(PH3)为掺杂气体,制备了n型氢化非品硅(a-Si:H)薄膜.研究了辉光放电功率对薄膜微结构和光电性能的影响,采用XRD和拉曼散射光谱对薄膜的微结构进行了表征,薄膜的折射率通过NKD-7000 W光学薄膜系统拟合,薄膜暗电导率利用高阻仪测试.结果表明:在辉光功率30～150 W范国内,所沉积的磷掺杂的硅薄膜为非晶态;非晶态薄膜结构中程有序度随辉光功率的增大先增人后减小,在功牢为100 W时非晶硅薄膜中程有序程度最高;薄膜的折射率随着辉光功率的增大先增加后减小,在功率为70 W达到最大值3.7;薄膜暗电导率在100 W最大,其最人值为9.32×10-3S/ cm.     

气压对VHF-PECVD制备的μc-Si:H 薄膜特性影响的研究

本文主要研究了用VHF-PECVD方法制备的不同工作气压的微晶硅薄膜样品.结果表明:沉积速率随反应气压的增大而逐渐增大;光敏性(光电导/暗电导)和激活能测试结果给出了相同的变化规律;傅立叶红外测试、X射线衍射和室温微区喇曼谱的结果都表明了样品的晶化特性;通过工艺的具体优化得出了器件级的微晶硅材料.     

X-ray diffraction study of p-(alkoxybenzylidene)-p′-toluidines: Crystal and molecular structure of C10H21O-C6H4-CH=N-C6H4-CH3

The crystal and molecular structure of p-(decaoxybenzylidene)-p′-toluidine C₁₀H₂₁O-C₆H₄-CH=N-C₆H₄-CH₃ is studied. The molecule is nearly planar. In the crystal packing, loose regions formed by aliphatic fragments of molecules alternate with pseudostacks of aromatic fragments of molecules that are related by the centers of symmetry. The stacks are built of dimers, in which molecules are linked by π-stacking interactions between benzene rings. There are no weak directional interactions between dimers in a stack. The presence of a single structure-forming element in the crystal, namely, the π-stacking interactions in the dimers, along with the similarity of the crystal packing to that of the C₈H₁₇O-homologue, which forms a nematic mesophase on melting, indicate that the crystals under study should exhibit nematic properties.     

Structure of (1αH,6βH,7αH,8αH)-1α,10α-epoxy-8β-hydroxy-germacr-2,11(13)-dien-6,12-olide (Incomptine B): A sesquiterpenoid lactone

C₁₅H₁₈O₄ is monoclinic,P2₁. Unit-cell dimensions at 293 K area=15.048(5),b=9.756(3),c=15.815(5)Å,=114.18(2)°,V=2118(1)ų,D _x=1.23 g cm^–3, andZ=6. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 2816 observed reflections toR=0.054. The structural features determined from chemical and spectroscopic studies are confirmed and extended. The incomptine B occurs as three independent molecules with different conformations. The stereochemistry at C(6), C(7), and C(8) is 6S, 7R, and 8R. The 10-membered ring has an approximate C₂ symmetry for the A, B, and C molecules. The -methylene -lactone ring adopts a half-chair conformation for molecule A, and a conformation intermediate between-envelope and half-chair for the B and C molecules, respectively. The structures are stabilized by a three-dimensional network of O-HO hydrogen bonds and several C-HO interactions.     

Crystal structures of acid ethylenediaminetetraacetates [Cd(H2 Edta)(H2O)] · 2H2O and [Mn(H2O)4][Mn(HEdta)(H2O)]2 · 4H2O

The crystal structures of [Cd(H₂ Edta)(H₂O)] · 2H₂O (I) and [Mn(H₂O)₄][Mn(HEdta)(H₂O)]₂ · 4H₂O (II) are studied by X-ray diffraction [R ₁ = 0.0209 (0.0272), wR ₂ = 0.0571 (0.0730) for 2551 (4025) reflections with I > 2σ(I) in I (II), respectively]. Structure I contains mononuclear [Cd(H₂ Edta)(H₂O)] complexes with the C ₂ symmetry, and structure II contains centrosymmetric trinuclear [Mn(H₂O)₄][Mn(HEdta)(H₂O)]₂ complexes. In I and II, the protonated ligands are hexadentate (2N + 4O), and the water molecule increases the coordination number of the metal atom to seven. The acid protons participate in short intermolecular hydrogen bonds, which are symmetric in II and asymmetric in I.     

An unusual function of the anion of 1-hydroxyethane-1,1-diphosphonic acid (H4 L): Crystal structure of [Ni(Phen)3](H7 L 2)0.5(H5 L 2)0.5 ⋅ 2H2O

Crystals of [Ni(Phen)₃](H₃ L)₂ ? 2H₂O (H₄ L is 1-hydroxyethane-1,1-diphosphonic acid) have been synthesized, and their structure has been determined by X-ray diffraction analysis. The cationic complexes [Ni(Phen)₃]²⁺, the centrosymmetric dimeric anions H₇ L ₂ ^? and H₅ L ₂ ^3? , and the molecules of crystallization water are the structural units of the crystal. The outer-sphere function of the H4 L anions in transition metal compounds and also the presence of differently charged dimeric anions are revealed for the first time. The structural units are joined together by an extended system of hydrogen bonds, including symmetric (or pseudosymmetric) hydrogen bonds in dimeric anions (O?O, 2.436 and 2.466 Å). The Ni-N(Phen) bond lengths fall in the range 2.074–2.107 Å. The compound has the structural formula [Ni(Phen)₃](H₇ L ₂)_0.5(H₅ L ₂)_0.5 ? 2H₂O.     

Production of Complex Hydrosulphates in the K3H(SO4)2–Rb3H(SO4)2 Series: Part I

Crystallography Reports - The phase equilibria in the K3H(SO4)2–Rb3H(SO4)2–H2O cross section have been investigated under isothermal conditions at 25°C. The concentration limits of...     

Metal-hydroxycarboxylate interactions: syntheses and structures of K2[VO2(C6H6O7)]2·4H2O and (NH4)2[VO2(C6H6O7)]2·2H2O

Potassium and ammonium dimeric (citrato)dioxovanadium(V) hydrate K₂[VO₂(H₂cit)]₂·4H₂O1 and (NH₄)₂[VO₂(H₂cit)]₂·2H₂O2 (H₄cit=citric acid) have been prepared and characterized by X-ray structure analyses. Vanadate1 crystallizes in the monoclinic space groupP2₁/n (No. 14) with unit cell parameters:a=9.304(2),b=11.756(2),c=11.911(2)Å, =111.72(3)°, andD _c=1.911 g/cm³,Z=2; Vanadate2 also crystallizes in the monoclinic space groupP2₁/n with unit cell parameters:a=9.719(2),b=11.111(3),c=11.294(2)Å, =109.03(2)°, andD _c=1.781 g/cm³,Z=2. Each dimer contains a centro-symmetric planar four-member V₂O₂ ring with two exocyclic citrate entities coordinated by the oxygen atoms of the hydroxy-and -carboxylate ligands, while the other two -carboxylate groups remain uncomplexed. Principal dimensions of the V–O bonds are 1.986(4)_av (hydroxy) and 1.980(3)Å(-carboxyl) for vanadate1, 1.988(2)_av (hydroxy) and 1.974(3)Å(-carboxyl) for vanadate2.