厚度对FeS2薄膜的光电性能的影响

采用Fe膜硫化工艺制备不同厚度的FeS2薄膜。研究了不同厚度FeS2薄膜的晶体结构，电阻率，载流子浓度，光吸收系数以及禁带宽度（Eg)。结果表明，随着薄膜厚度的增加，FeS2的电阻率升高，载流子浓度下降，在高吸收区FeS2薄膜的光吸收系数也呈下降趋势。当薄膜厚度小于130nm时，薄膜厚度增加可导致其禁带宽度上升，当薄膜厚度大于130nm时，薄膜厚度增大反而会导致禁带宽度下降。     

Fe膜硫化合成FeS2薄膜的光电性能

研究了纯Fe在200－600℃硫化10h 及500℃硫化1－10h条件下形成FeS2薄膜过程中的结构，光吸收，禁带宽度及电阻率的变化规律，纯Fe膜虽在200℃即有硫化反应发生，但只有在300℃以上硫化时，薄膜才会出现明显的禁带宽度，并随硫化温度升高，禁带宽度下降，硫化时间对薄膜禁带宽度影响不明显，随硫化温度升高及硫化时间延长，薄膜电阻率上升，由于硫化参数的变化能够引起薄膜结构，晶体缺陷及薄膜完整的性的变化，因此可以导致薄膜光电性能的变化。     

Fe膜硫化合成不同厚度的FeS2薄膜组织结构与电学性能

对热蒸镀的不同厚度纯Fe膜进行硫化处理,制备了厚度在70~600nm范围内变化的FeS2薄膜,研究了薄膜厚度对FeS2薄膜组织结构和电学性能的影响。结果表明,虽然不同厚度的FeS2薄膜晶格点阵畸变度不同,但晶粒均较为细小。较厚的薄膜表面更为平整并且组织更为均匀。随薄膜厚度增加,载流子浓度下降而迁移率上升。当膜厚超过400nm后,载流子浓度上升而迁移率下降。在膜厚约为130nm时,电导率出现极大值。     

直流磁控溅射法制备单一相高质量β-FeSi2薄膜

报道了在单晶Si(100)衬底上,采用室温直流磁控溅射Fe-si组合靶的方法,并经过后续气氛退火来制备β-FeSi2薄膜的结果.主要研究了退火时间、退火温度等实验条件对样品结构特性、光学特性和电学特性的影响,制备出了单一相高质量的βFeSi2薄膜.霍尔测试表明未掺杂薄膜是P型导电的,载流子浓度5.7147×1016 cm-3,空穴迁移率168cm2/Vs.由反射一透射法得到薄膜的禁带宽度为0.879eV,吸收系数在光子能量为1.0eV时达到了1.42×105cm-1.基于以上优异的光电性能,β-FeSi2薄膜可望用作太阳电池的有源层.     

Cdln2O4膜红外性质分析

利用射频反应溅射Cd-In合金靶沉积的CdIn_2O_4薄膜是n型高兼并半导体,其红外反射率随溅射气体中氧浓度的不同而有异,相同氧浓度下沉积的薄膜经过退火处理后红外反射率也会发生变化。原因是不同氧浓度下沉积薄膜的氧空位不同,其自由载流子浓度也就不同,从而使薄膜有不同的吸收系数。实验结果与理论计算值符合较好。     

FeS_2薄膜光电性能研究进展

对FeS2 薄膜光电性能的研究现状进行了分析 ,综述了制备方法、硫化工艺及掺杂元素对FeS2 薄膜光电性能的影响以及光电转换效率的研究进展 ,讨论了FeS2 薄膜这种先进太阳能电池材料研究中现存的问题和发展方向。     

FeS2薄膜光电性能研究进展

对FeS2薄膜光电性能的研究现状进行了分析。综述了制备方法,硫化工艺及掺杂元素对FeS2薄膜光电性能的影响以及光电转换效率的研究进展。讨论了FeS2薄膜这种先进太阳能电池材料研究中现存的问题和发展方向。     

光伏太阳电池研究中的光声技术

本文报道了采用光声光谱技术测量某些半导体光电材料的光吸收特性及禁带宽度的结果。样品为高纯CdS、掺杂的CdS和电沉积在Ni片上的CdSe薄膜。用光声功率法测定了CdS-Cu_2S固体光伏电池和CdSe∣Na_2S-S-NaOH∣Pt电化学光伏电池的光电流谱和光谱响应。同时也研究了氧化-还原电解液(如Na_2S-S-NaOH)的光吸收行为。灾验结果表明,光声光谱技术对于光伏太阳电池的研究是一种很有用的工具。     

水掺杂对臭氧基原子层沉积二氧化硅钝化特性研究

该文主要研究水掺杂对臭氧基原子层沉积二氧化硅薄膜的影响。通过在臭氧中掺杂少量水作为混合氧化剂,有效降低了原子层沉积二氧化硅薄膜内部碳和氮杂质元素的含量,并提高其成膜速率及薄膜质量;同时,水的掺杂还能够适当提高二氧化硅薄膜内部及其与硅界面处的氢元素浓度,使其具有更强的氢钝化效果。臭氧中掺杂水制备的二氧化硅薄膜能够在较低的退火温度下获得较高的钝化性能;而固定正电荷密度较臭氧制备的二氧化硅薄膜显著降低。     

掺硼（B）非晶硅（a—Si：H）材料固相晶化（SPC）的研究

对掺硼（Ｂ）材料的固相晶化进行了研究。通过对不同掺Ｂ浓度的ａ－Ｓｉ：Ｈ样品退火前后的Ｘ射线衍射，光吸收系数、电导率、激活能及Ｈａｌｌ迁移率的测量发现，Ｂ原子在固相晶化过程中起晶核作用，晶化后的样品具有较高的迁移率及电导率，同时具有较大的禁带宽度。当掺Ｂ浓度仅为０．１７％时，晶化后样品的电导率４．３５ｓｃｍ＾－１，迁移率为１４０ｃｍ＾２Ｖ＾－１Ｓ＾－１，禁带宽度Ｅ０４＝２．１６ｅＶ。该材料是一种较好     

Analysis of free-carrier optical absorption used for characterization of microcrystalline silicon films

The analysis of free-carrier optical absorption was applied to investigation of electrical properties for doped microcrystalline silicon films formed at 100–180°C by the RF-plasma-enhanced chemical vapor deposition method. The analysis gave in-depth characteristics of the carrier mobility and the carrier density. The electron mobility was 8 cm²/Vs (phosphorous doped) and 6 cm²/Vs (boron doped) at the surface region and it decreased to 1 cm²/Vs at bottom film/substrate interfaces. The carrier mobility and density were much higher than those obtained by Hall effect current measurements. It shows the existence of substantial non-activated and disordered regions among crystalline grains.     

Effect of oleylamine on microwave synthesized Cu2ZnSnS4 nanocrystals for photovoltaic junctions

Cu₂ZnSnS₄ (CZTS) with its high absorption coefficient, optimal band gap, and non‐toxic, earth‐abundant elemental constituents is a promising absorber material for low cost and high‐performance photovoltaics. CZTS nanocrystals were prepared by microwave‐assisted thermolysis method using ethylene glycol solvent in a rapid and energy efficient process with and without oleylamine as additional capping agent. X‐ray diffraction data indicated crystallite sizes of 5 and 12 nm respectively. Raman spectra showed the formation of pure Cu₂ZnSnS₄ phase in both cases. With pure ethylene glycol solvent, field emission scanning electron microscopy images showed particle sizes around 250 nm, ultraviolet‐visible absorption data gave optical band gap of 1.52 eV and Hall measurements yielded electrical resistivity ~70 Ωcm, carrier density ~2.7 × 10¹⁶/cm³, and hole mobility ~3.24 cm²/Vs. Adding optimum amount of oleylamine reduced the particle size to 100 nm and lower. The optical band gap reduced to 1.48 eV and electrical resistivity, carrier concentration, and Hall mobility changed to ~5.9 × 10⁴ Ωcm, 2.57 × 10¹²/cm³, and 4.1 cm²/Vs respectively. A knee voltage of ~0.8 V shown by CZTS/CdS p‐n junction indicated that a good V_oc can be expected from a solar cell constructed with the CZTS nanocrystals as absorber layer.     

Defect reduction in electrochemically deposited CdS thin films by annealing in 02

Using the electrochemical deposition method, CdS thin films were deposited from acid solutions (pH = 2.5) containing CdS0₄ and Na₂S₂0₃ on indium-oxide coated glass substrates. These films were annealed in N₂, air, or O₂ atmosphere at 200–500°C for 30 min. Photoluminescence spectra were measured at 77 K. For the films annealed in N₂, the band edge emission became weaker and the luminescence due to defects shifted to longer wavelengths as the annealing temperature was raised above 300°C. However, for the films annealed in air or O₂, the band edge emission was observed strongly irrespective of the annealing temperature and the luminescence due to defects was weak. Thus the O₂ annealing is useful for the defects reduction.     

Synthesis of CuInS2 films by sulphurization of Cu/In stacked elemental layers

CuInS₂ films were synthesized by sulphurization of In/Cu stacked elemental layers (SEL) deposited onto glass and Mo-coated glass substrates by graphite box annealing at temperatures of 620–880 K. The films thus synthesized were characterized by measuring electrical, optical, microstructural and photoluminescence properties. The microstructure and hence the physical properties of the films depended critically on the amount of sulphur incorporation. Nature of charge carriers depended on both Cu/In and S/(Cu+In) ratio and the carrier concentration varied between 10¹⁴ and 10¹⁸ cm⁻³. Grain boundary scattering effects were critically studied by measuring the electrical conductivity and Hall mobility simultaneously on the same sample. The shape of the grains depended critically on the sulphur content. The PL spectra were dominated by the excitonic peak 788 nm followed by another peak at 892 nm which may be ascribed to the DA transition.     

Ag-doped PbS thin films by nebulizer spray pyrolysis for solar cells

Silver (Ag)-doped PbS (PbS:Ag) thin films of 616 to 745 nm in thickness were prepared on glass substrates via cost-effective nebulizer spray method by adding different Ag levels from 2% to 8% at 200°C. For solar cell applications, the effect of Ag doping concentration on structural, morphological, optical, photoluminescence, and electrical chattels of PbS thin film has been studied. X-ray diffraction pattern confirmed the polycrystalline behavior of the prepared PbS:Ag films with cubic crystalline nature. The crystalline size and texture coefficient were increased by increasing Ag doping concentration. From the morphological studies by scanning electron microscope (SEM) and atomic force microscope (AFM), the grain size of the films and surface roughness values were increased for the increase in Ag doping concentration. EDS spectra confirmed the existence of Ag, Pb, and S elements in the select 6% Ag-doped PbS film. Peaks related to silver oxide started to emerge at 6% of Ag doping level. The optical direct band gap value was reduced from 1.51 to 1.17 eV for Ag doping from 2% to 6% and thereby slightly increased as 1.79 eV for 8% Ag doping level. For all PbS:Ag films, the photoluminescence spectrum emitted a strong near band edge (NBE) emission at approximately 580 nm, meaning better optical quality. Hall effect measurements evidenced that Ag doping provides enhancement on the characteristics of mobility, carrier concentration, and resistivity with p-type conducting nature. The observed high carrier concentration and low resistivity values were 4.32 × 10¹⁴ cm⁻³ and 80 Ωcm, for 6% Ag-doped PbS film. The FTO/CdS/PbS:Ag heterostructure solar cell was formed from 6% Ag-doped film.     

Carrier transport and structural properties of polysilicon films prepared by layer-by-layer technique

Polycrystalline silicon (poly-Si) films have been deposited on glass substrates by a layer-by-layer technique at very low temperature, 300°C, using fluorinated precursors. The electronic transport was characterized by Hall effect and conductivity measurements over a wide temperature range, 100 K to 400 K. The structure of the materials is a function of the film thickness. The measured Hall mobility increases as the thickness increases. The Hall mobility Arrhenius plot shows linear dependence with a negative slope over the temperature range examined, suggesting that carrier conduction is limited by grain boundary barriers.     

Anomalous Hall effect of PdCo alloy thin films to detect low hydrogen concentration in air

The anomalous Hall effect of thin PdCo films (Pd_0.8Co_0.2 alloy films; 5, 15, and 30 nm thick) subjected to various hydrogen concentrations in the gas phase was investigated. The Hall voltage of the 15 and 30 nm thick PdCo films against an external magnetic field exhibited hysteresis, indicating the anomalous Hall effect of PdCo. The hydrogen absorption in the 5 nm PdCo film decreased the Hall voltage in all considered magnetic fields. Moreover, the slope of the Hall voltage around a zero magnetic field decreased. When N₂ was used as the carrier gas, the slope was proportional to the logarithm of the hydrogen concentration. For dry air, the slope differed from and was similar to that for N₂ below and above hydrogen concentrations of 0.5% and 1.0%, respectively. The adsorbed oxygen on the PdCo surface disturbed the dissolved hydrogen in PdCo at low hydrogen concentrations in dry air.     

Hall effect analysis of liquid phase epitaxy silicon for thin film solar cells

We use variable temperature Hall effect measurements to determine the doping concentration, impurity compensation, and mobility of n- and p-type liquid phase epitaxy (LPE) silicon layers that are grown from indium solutions onto silicon substrates. Our theoretical analysis of carrier concentration versus temperature data considers temperature-dependent effective masses, Fermi-Dirac statistics, multiple majority impurity levels, excited impurity states, and the temperature dependence of the Hall scattering factor. The measured Hall mobilities and computed compensation ratios in these LPE silicon thin films are within the range of values that have been measured in bulk silicon crystals. Such LPE layers are therefore suitable for the fabrication of high efficiency silicon thin film solar cells.     

Structural and thermoelectric properties of nanostructured p-SnO thin films grown by e-beam evaporation method

Today, the earnest need for earth-abundant and environmentally friendly thermoelectric materials has revealed the importance of semiconductor metal oxides in order to eliminate the barrier towards their wide-ranging use in industrial applications. In the present work, we demonstrate the synthesis of p-type tin oxide thin films on quartz glass and Si substrates by using electron beam evaporation technique followed by rapid thermal annealing process at 200 °C for 20 min in Ar-atmosphere. Annealing-induced structural, electrical, optical and thermoelectric properties of pristine and annealed SnO thin films are primarily studied. The compositional and structural analysis of SnO films are performed by using X-Ray Diffraction, Scanning Electron Microscope as well as Atomic Force Microscope. Moreover, the mechanism of thermoelectric transportation at different measurement temperatures is deeply inspected via thermoelectric measurements. The Seebeck coefficient, carrier concentration and hole mobility in conjunction with the development of thin film nanostructures are discussed, predominantly. The optimal annealing may tune structural, electro-optic and thermoelectric properties of SnO films for the commercial-level maturity of thermoelectric devices for energy applications.