射频功率对ITZO薄膜结构、形貌及光电特性的影响

在室温下采用射频磁控溅射方法在玻璃衬底上制备了200 nm厚的铟锡锌氧化物(ITZO)薄膜,研究了不同功率下薄膜结构、形貌、光学和电学性能的变化规律.结果表明,ITZO薄膜为非晶薄膜并且有着良好的光电特性,其平均光学透过率超过了84;,载流子霍尔迁移率高达24 em2·V-1·s-1.随着射频功率从50 W上升到100 W,薄膜的光学带隙从3.68 eV逐渐增加到3.76 eV.研究发现,薄膜的电学性能强烈依赖于射频功率.随着功率的增加,薄膜的电学性能呈现出先变好后变差的变化规律.当射频功率为80 W时,ITZO薄膜拥有最佳的电学性能,其电阻率为3.80×10-4Ω·cm,载流子浓度为6.45×1020 cm-3,霍尔迁移率为24.14 cm2·V-1· s-1.     

溅射气压对硼掺杂ZnO薄膜光电特性的影响

采用脉冲磁控溅射系统在玻璃衬底上制备了ZnO∶B薄膜,利用霍尔测试仪和紫外-可见光-近红外分光光度计及逐点无约束最优化法,研究了溅射气压(0.1 ～3 Pa)对ZnO薄膜的光学和电学特性的影响.结果表明:ZnO∶B薄膜在可见光区域内的平均透光率高于80;,近红外波段的透过率及薄膜的电阻率与溅射气压成正比;折射率n随溅射气压降低呈下降趋势,其值介于1.92 ～2.09之间;在较低的溅射气压下(PAr=0.1 Pa)获得的薄膜电阻率最小(3.7×10-3Ω·cm),且对应着小的光学带隙(Eg=3.463 eV).     

射频反应磁控溅射制备ZnO薄膜的微结构及其光学性能

采用射频反应磁控溅射技术在石英和Si衬底上制备了高度c轴择优取向的ZnO薄膜,样品的氧氩流量比分别为10:40,20:40,30:40,40:40.利用X射线衍射仪、表面轮廓仪、原子力显微镜和紫外-可见分光光度计研究了样品的微结构与光学特性.研究表明:氧氩流量比为30:40的样品结晶质量最好.所制备的ZnO薄膜的可见光平均透射率均大于87;.随着氧氩流量比的增大,薄膜的透射率呈非单调变化,氧氩流量比为30:40的样品在可见光范围的平均透射率可达93;.光学带隙随着氧氩流量比的增大,先增大后减小.与块材ZnO的带隙(3.37 eV)相比,ZnO薄膜的带隙均变窄.     

PECVD沉积参数对非晶硅向微晶硅薄膜转化的影响

采用等离子体增强化学气相沉积(PECVD)系统,以硅烷和氢气为反应气源,通过改变射频功率、硅烷浓度来制备氢化硅基薄膜材料.研究了沉积参数的变化对硅基薄膜材料微结构的影响.通过红外吸收谱、紫外可见光谱以及X射线衍射谱对样品材料进行表征.实验结果表明,随着射频功率的增加,薄膜中氢含量也相应地增大,而光学带隙表现出先增大后减小的规律.当硅烷浓度逐渐降低时,薄膜材料的光学带隙相应地降低,并从非晶硅薄膜逐渐向微晶硅薄膜材料转变,且薄膜材料在(111)方向的晶粒尺度达到了10.92 nm.实现了在高沉积压强、大射频功率、低硅烷浓度条件下可以有效优化改善硅基薄膜质量.     

B掺杂对平面结构MOCVD-ZnO薄膜性能的影响

本文研究了B2H6掺杂流量(B掺杂)对平面结构MOCVD-ZnO薄膜的微观结构和光电性能影响.XRD、SEM和AFM测试的研究结果表明,玻璃衬底上制备的ZnO薄膜具有(002)峰择优取向的平面结构,B掺杂使薄膜的球状晶粒尺寸变小,10 sccm流量时晶粒尺寸为～15 nm.ZnO:B薄膜的最小电阻率为5.7×10-3Ω·cm.生长的ZnO薄膜(厚度d=1150 nm)在400～900 nm范围的透过率为82;～97;,且随着B2H6掺杂流量增大,光学吸收边呈现蓝移(即光学带隙Eg展宽)现象.     

射频磁控溅射法制备Cu3N薄膜及其性能研究

采用反应射频磁控溅射法,在氮气和氩气的混合气体氛围中,玻璃基底上制备出了具有半导体特性的氮化铜(Cu3N)薄膜,并研究了混合气体中氮气分量对Cu3N薄膜的择优生长取向、平均晶粒尺寸、电阻率和光学带隙的影响.原子力显微镜,X射线衍射仪,四探针电阻仪,紫外可见光谱分析及纳米压痕仪等测试结果表明:薄膜由紧密排列的柱状晶粒构成,表面光滑致密;随着氮气分量的增加,Cu3N薄膜由沿(111)晶面择优生长转变为沿(100)晶面择优生长,晶粒尺寸变小,电阻率ρ从1.51×102Ω·cm逐渐增加到1.129×103Ω·cm;薄膜的光学带隙在1.34～1.75eV间变化;薄膜的硬度约为6.0GPa,残余模量约为108.3GPa.     

Ti含量对溶胶-凝胶法制备Ti、Ga共掺ZnO薄膜性能的影响

采用溶胶-凝胶旋涂法在玻璃衬底上沉积纳米结构Ti、Ga共掺ZnO薄膜(TGZO,Ga掺杂量为1.0;(原子分数,下同)),用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、分光光度计(UV-Vis)、四探针测试仪、霍尔效应测试仪研究了Ti含量对TGZO薄膜的物相组成、表面形貌、电学和光学性能的影响.结果表明:所有TGZO薄膜均表现出六方纤锌矿的多晶结构,并具有(002)择优取向生长,在380～780 nm波长范围内具有良好的透射率(>86;);随着Ti含量的增加,TGZO薄膜的晶粒尺寸和可见光平均透射率均先增加后减小,而光学带隙和电阻率先减小后增加;Ti掺杂量为1.0;时,具有最高的可见光透射率92.82;,最窄的光学带隙3.249 eV,以及最低电阻率2.544×10-3Ω·cm.     

氧气流量对射频磁控溅射制备Cu2O薄膜性能的影响

通过磁控溅射方法在玻璃衬底上制备Cu2O薄膜,采用X射线衍射(XRD)、分光光度计、原子力显微镜(AFM)和X射线光电子能谱(XPS)等研究了氧气流量对Cu2O薄膜性能的影响.结果表明:氧气流量为4.2 sccm时,薄膜为单相的Cu2O,具有较高的结晶质量和可见光透过率,光学带隙为2.29 eV,薄膜的导电类型是p型且空穴浓度为2×1016 cm-3.通过XPS能谱分析Cu 2p3/2和O 1s结合能,确定了薄膜中Cu以+1价存在.     

溅射功率对铝铬共掺杂氧化锌透明导电薄膜特性的影响(英文)

室温下,利用直流磁控溅射法在玻璃衬底上制备了铝铬共掺杂氧化锌薄膜,研究了溅射功率(55-130 W)对薄膜结构、残余应力、表面形貌及其光电性能的影响。结果表明,ZnO(002)衍射峰的强度随着溅射功率的增大而增强,晶体结构得以改善。晶格常数、压应力和电阻率均随着溅射功率的增大而减小。当溅射功率为130 W时,制备的ZnO∶Al,Cr薄膜的最低电阻率可达1.09×10-3Ω.cm。功率由55 W增大到130 W时,光学带隙由3.39 eV增大到3.45 eV。紫外-可见透射光谱表明,所有薄膜在可见光范围内平均透过率均超过89%。     

薄膜厚度对 Mn-W 共掺杂 ZnO 透明导电薄膜性能的影响

利用直流磁控溅射法在低温玻璃衬底上制备了高导电透明的 Mn-W 共掺杂 ZnO(ZMWO)薄膜,并研究了厚度对薄膜结构、光学及电学性能的影响.X 射线衍射结果表明 ZMWO 均为六方纤锌矿结构的多晶薄膜,具有垂直于衬底方向的 c 轴择优取向.薄膜厚度对 ZMWO 薄膜的晶化程度、电阻率和方块电阻有很大影响.当薄膜厚度从97 nm 增大到456 nm 时,ZMWO 薄膜的晶化程度提高,而电阻率和方块电阻减小.当厚度为 456 nm 时,所制备ZMWO 薄膜的电阻率达到最小,其值仅为8.8×10-5 Ω·cm,方块电阻为1.9 Ω/□.所有薄膜样品在可见光区的平均透过率都较高,其值约为89;.当薄膜厚度从97 nm 增大到 456 nm时,光学带隙从3.41 eV增大到3.52 eV.     

利用快速热退火法制备多晶硅薄膜

为了制备优质的多晶硅薄膜,该论文研究了非晶硅薄膜的快速热退火(RTA)技术.先利用PECVD设备沉积非晶硅薄膜,然后把其放入快速热退火炉中进行退火.退火前后的薄膜利用X射线衍射(XRD)仪、Raman光谱仪及扫描电子显微镜(SEM)测试其晶体结构及表面形貌,利用电导率测试设备测试其暗电导率.研究表明退火温度、退火时间以及沉积时的衬底温度对非晶硅薄膜的晶化都有很大的影响.     

Surface wave attenuation by silicon,hydrogen, and deuterium in amorphous silicon films

Motions of silicon, hydrogen, and deuterium in sputtered thin films of a-Si, a-Si:H, and a-Si:D were studied by measurements of the attenuation of surface acoustic waves propagating along the surface of piezoelectric crystals which were covered by the thin films. It is concluded that there are H and D atoms (ions) which are not directly associated with the Si bonds. Some of the H and D atoms (ions) are configurationally rearranged at room temperature. A part of the hydrogen (deuterium) or argon is located in voids.     

Characterization of HF-PECVD a-Si:H thin film solar cells by using OES studies

Hydrogenated amorphous silicon (a-Si:H) films show considerable potential for the fabrication of thin film solar cells. In this study, the a-Si:H thin films have been deposited in a parallel-plate radio frequency (RF) plasma reactor fed with pure SiH₄. The plasma diagnostics were performed simultaneously during the a-Si:H solar cell deposition process using an optical emission spectrometer (OES) in order to study their correlations with growth rate and microstructure of the films. During the deposition, the emitting species (SiH*, Si*, H*) was analyzed. The effect of RF power on the emission intensities of excited SiH, Si and H on the film growth rate has been investigated. The OES analysis revealed a chemisorption-based deposition model of the growth mechanism. Finally, the a-Si:H thin film solar cell with an efficiency of 7.6% has been obtained.     

Effect of illumination on hydrogenated amorphous silicon thin films doped with chalcogens

Hydrogenated amorphous silicon thin films doped with chalcogens (Se or S) were prepared by the decomposition of silane (SiH₄) and H₂Se/H₂S gas mixtures in an RF plasma glow discharge on 7059 corning glass at a substrate temperature 230 °C. The illumination measurements were performed on these samples as a function of doping concentration, temperature and optical density. The activation energy varied with doping concentration and is higher in Se-doped than S-doped a-Si:H thin films due to a low defect density. From intensity versus photoconductivity data, it is observed that the addition of Se and S changes the recombination mechanism from monomolecular at low doping concentration films to bimolecular at higher doping levels. The photosensitivity (σ_ph/σ_d) of a-Si, Se:H thin films decreases as the gas ratio H₂Se/SiH₄ increased from 10^?4 to 10^?1, while the photosensitivity of a-Si, S:H thin films increases as the gas ratio H₂S/SiH₄ increased from 6.8 × 10^?7 to 1.0×10^?4.     

热丝辅助MW ECR CVD技术高速沉积高质量氢化非晶硅薄膜

氢化非晶硅薄膜具有优异的光电特性,在制备薄膜太阳能电池中有重要的应用.本文采用热丝辅助MWECR CVD技术,通过调整各种工艺参数,制备了高沉积速率(DR＞2.5nm/s)及高光敏性(σph/σD＞105)的氢化非晶硅薄膜.实验表明,在衬底表面温度的分布中,热丝辐射和离子轰击引起的温度对薄膜的光敏性影响较大;在薄膜沉积的最后几分钟适当加大H2稀释率,有利于薄膜光电特性的改善.     

Correlation between micro-roughness,surface chemistry,and performance of crystalline Si/amorphous Si:H:Cl hetero-junction solar cells

The correlation between micro-roughness, surface chemistry, and performance of crystalline Si/amorphous Si:H:Cl hetero-junction solar cells is discussed through a deposition study of amorphous Si:H:Cl (a-Si:H:Cl) films by rf plasma-enhanced chemical vapor deposition using a SiH₂Cl₂–H₂ mixture. The degree of H- and Cl-termination on the growing surface determined the degree of micro-roughness at the p-type a-Si:H:Cl/intrinsic a-Si:H:Cl interface and solar cell performance. A higher degree of Cl-termination compared to H-termination was effective to suppress the micro-roughness at the growing surface and oxygen incorporation into the film, as well as chemical reduction of the intrinsic a-Si:H:Cl layer during the underneath p-layer formation. The study showed that a-Si:H:Cl deposited from SiH₂Cl₂ is a potential material for c-Si hetero-junction solar cells with an intrinsic a-Si:H:Cl thin layer.     

Characterization of a-B5C:H prepared by PECVD of orthocarborane: Results of preliminary FTIR and nuclear reaction analysis studies

The electronic properties of a-Si:H vary with hydrogen passivation of dangling bond defects. It appears this effect is also operative in semiconducting amorphous hydrogenated boron carbide (a-B₅C:H). Therefore, the ability to quantify the amount of hydrogen will be key to development of the materials science of a-B₅C:H. The results of an initial investigation probing the ability to quickly correlate hydrogen concentration in a-B₅C:H films with infrared spectroscopy are reported. a-B₅C:H thin films were growth on Si (1 1 1) substrates by plasma-enhanced chemical vapor deposition (PECVD) using sublimed orthocarborane and argon as the precursor gas. Nuclear reaction analysis (NRA) was performed to quantify the atomic concentration of H in the a-B₅C:H films. While the observed vibronic structure does not show stretches due to terminal C–H or bridging B–H–B, analysis of the terminal B–H stretch at ～2570 cm^?1 gives a proportionality constant of A = 2 × 10²² cm^?2. We conclude that the methods previously developed for correlating H concentration to infrared data in a-Si:H are similarly viable for a-B₅C:H films.     

Advanced deposition phase diagrams for guiding Si:H-based multijunction solar cells

Phase diagrams have been established to describe very high frequency (vhf) plasma-enhanced chemical vapor deposition (PECVD) of intrinsic hydrogenated silicon (Si:H) and silicon–germanium alloy (Si_1?xGe_x:H) thin films on crystalline Si substrates that have been over-deposited with n-type amorphous Si:H (a-Si:H). The Si:H and Si_1?xGe_x:H films are prepared under conditions used for the top and middle i-layers of high efficiency triple-junction a-Si:H-based n–i–p solar cells. Identical n/i cell structures were co-deposited in this study on textured (stainless steel)/Ag/ZnO which serve as substrate/back-reflectors in order to relate the phase diagrams to the performance parameters of single-junction solar cells. This study has reaffirmed that the highest efficiencies for a-Si:H and a-Si_1?xGe_x:H solar cells are obtained when the i-layers are prepared under previously-described maximal H₂ dilution conditions.     

Spectroscopic and electrical detection of intermediate phases and chemical bonding self-organizations in (i) dielectric films for semiconductor devices,and (ii) chalcogenide alloys for optical memory devices

This paper presents a discussion of intermediate phases in thin film materials that have been incorporated into liquid crystal displays, LCDs, and optical memory thin film devices. The formation of intermediate phases in the a-Si₃N₄:H (a-Si:N:H) alloys used for gate dielectrics in thin film transistors, TFTs, of LCDs, and the a-Ge–Sb–Te (GST) alloys used for read-write optical writing and storage in optical memory discs are qualitatively different than those first addressed by the Boolchand group in Ge–Se bulk glass alloys. In the a-Si:N:H and a-GST thin films, the chemical self-organizations that suppress percolation of strain, involve chemically-ordered bonding arrangements that break bond bending constraints at the four-fold coordinated Si and Ge atoms in a-Si:N:H and a-GST, respectively. In the GST alloys, this results in over-coordinated and under-coordinated atomic constituents, or valence alternation pairs, VAPs, of charged defects. Finally, other technologically important systems in which broken constraints, and/or VAP defects are important in intermediate phase formation include group IVB (Ti, Zr and Hf) Si oxynitride alloys, and hydrogenated amorphous Si (a-Si:H).     

Hydrogenated amorphous silicon with substrate-dependent structure

Hydrogenated amorphous silicon (a-Si:H) thin films grown at 250°C on (1 0 0) crystalline substrate using plasma-enhanced chemical vapor deposition (PECVD) with SiH₄/H₂ gas flow ratio equal to 5/1 (sccm) are investigated by transmission electron microscopy. It is found that the thin film is totally amorphous when grown on a glass substrate. But when the substrate is changed to crystalline silicon, some crystalline grains are found embedded in the amorphous structure in certain regions even if the thickness of the film reaches 600 nm. It is suggested that the amorphous silicon film grown on a crystalline silicon substrate at a temperature of 250°C without heavy H₂ dilution is a mixed network of a small amount of crystalline silicon and the major portion of amorphous silicon.