Spray pyrolysis deposition of undoped SnO2 and In2O3 films and their structural properties

In this paper the results of structural analysis of the SnO₂ and In₂O₃ films deposited by spray pyrolysis are presented. The main goals of this analysis are summarizing the results obtained in this field, highlighting a correlation between parameters of film deposition and the material structure and formulating some general regularities, typical for metal oxides. Peculiarities and mechanisms of pyrosol deposition as well as advantages and disadvantages of this technology for deposition of the films with required parameters were also discussed. It is shown that this technology has great potential for controlling structural parameters of metal oxides such as thickness, the grain size, texturing, roughness, the grain faceting and the porosity.     

Strongly in-plane magnetized FePt thin film on ultrathin Fe underlayer

The effect of ultrathin Fe underlayer on the strong in-plane magnetization of FePt magnetic thin film was investigated. This FePt thin film could be attained using the ultrathin Fe underlayer with 1 nm thickness. The in-plane coercivity of FePt film with 20 nm thickness grown on ultrathin Fe underlayer was high up to 7400 Oe. However, its out-of-plane coercivity was extremely low to 350 Oe compared to those of FePt thin films in other conventional studies. This result indicates that FePt thin film was strongly in-plane magnetized by ultrathin Fe underlayer. The strong ordering phase transformation kinetics and the high texturing to in-plane direction of the FePt thin film by ultrathin Fe underlayer were confirmed by Kinetics Monte Carlo (KMC) simulation and XRD measurement result, respectively. It is also supposed that they are associated with the reduction of an interface free energy between the film and the substrate with an introduction of ultrathin underlayer.     

A new texturing technique of monocrystalline silicon surface with sodium hypochlorite

This work proposes a new texturing technique of monocrystalline silicon surface for solar cells with sodium hypochlorite. A mixed solution consisting of 5 wt% sodium hypochlorite and 10 vl% ethanol has been found that results in a homogeneous pyramidal structure, and an optimal size of pyramids on the silicon surface. The textured silicon surface exhibits a lower average reflectivity (about 10.8%) in the main range of solar spectrum (400–1000 nm).     

Comparison of expander and Instant Controlled Pressure-Drop DIC technologies as thermomechanical pretreatments in enhancing solvent extraction of vegetal soybean oil

As an intensification process of the unit operation of vegetable oil extraction, the cooking pre-treatment systematically results in damaging thermal degradations. However, recently, two thermomechanical expansion processes have been suggested and applied at industrial scales to pre-treat oilseeds: expansion and instant controlled pressure drop DIC. In both cases, it is a flash transformation from high-temperature/high-pressure to 100 °C/atmospheric pressure and 33 °C/vacuum phases, respectively. The use of DIC resulted in cumulative impact yields of 247 mg oil/g db, compared to 210, 230, and 224 for cracking, cracking/blocking, and expanding, respectively. To achieve the same yields obtained in 160 min for cracked or cracked/flaked soybean, the expander took 120 min against 35 min for DIC. Besides, thanks to the short heat treatment and the induced instant cooling, DIC allowed the highest preservation of soybean oil quality, with fatty acid concentrations almost identical to that of untreated seeds.Practical impactsIn the sector of the vegetal oil industry, researchers and engineers mostly look for increasing the extraction yields while preserving or improving the sensorial and biochemical quality of the oil. Henceforth, the modification of the oleaginous seed texture may usually be the major factor affecting and normally enhancing the capacity of extraction. Based on the improvement of material structure through adequate expansion, the higher the volume of vapor issued from the autovaporization throughout the instant controlled pressure-drop (DIC) technology, the higher the oil yields. Moreover, using the instantaneous thermodynamic theory, the feasibility of integrating DIC technology as an HTST treatment in the industrial-scale soybean extraction process could be performed and optimized without any biochemical degradation.     

不同形貌的金字塔结构对硅片表面钝化和异质结太阳电池的影响

在晶体硅表面沉积本征非晶硅层的异质结（SHJ）太阳电池以其高效率、高稳定性、低成本和低温制备等诸多优势被人们广泛关注. 在晶体硅衬底表面制绒,是提高太阳电池效率的有效途径之一. 本文采用四甲基氢氧化铵（TMAH）在硅片表面制备了不同形貌的金字塔结构的硅异质结电池衬底,并应用到电池中. 通过研究不同金字塔的形貌,光学特性以及电学特性,找出提高硅片钝化效果,改善异质结电池的性能的优化的金字塔结构. 结果表明：2%（w）TMAH,10%（w）异丙醇（IPA）可以在硅片表面制得标准四面体金字塔结构. 和其它两种金字塔结构相比较,标准四面体金字塔结构绒面衬底反射率最低,可以提高太阳电池的短路电流密度（J_sc）. 同时,这种结构金字塔形貌可以提高钝化效果,改善电池各项性能参数.     

多晶硅表面酸腐蚀制备绒面研究

采用各向同性腐蚀法制备多晶硅绒面,腐蚀液为HF和HNO3的混合溶液,缓和剂为NaH2PO4.2H2O溶液.利用SEM、AFM和紫外分光光度计对硅片绒面进行检测和分析,初步探讨了酸腐蚀机理.结果表明:采用NaH2PO4.2H2O溶液作为缓和剂,腐蚀后的硅片表面具有均匀的腐蚀坑,表面陷光效果较好,通过优化各种参量,反应速度可以控制在2 μm/min左右,适合工业生产的要求.在富HF时,硅片表面易形成尖锐边缘的腐蚀坑,出现或多或少的小孔,反射率最低可达16.5%～17.5%|在富HNO3时,硅片表面易形成腐蚀坑较浅、尺寸偏大的气泡状绒面或光面,反射率较高.     

Solar cell fabrication using edge-defined film-fed growth (EFG) silicon wafers

The insufficient supply of polysilicon is limiting the growth of the segment of the photovoltaic industry using silicon materials. Because it is grown directly in the form of ribbon from a silicon melt, edge-defined film-fed growth (EFG) silicon ribbon is a promising alternative for cutting down wafer costs by reducing the polysilicon consumption and eliminating kerf loss. In this paper, we will discuss the various properties that can be achieved with for low cost and high-efficiency EFG silicon ribbon solar cell fabrication. Boron-doped p-type EFG ribbon silicon wafers with resistivities of 2-4 Ω cm and a size of 125 mm × 125 mm were used. The major fabrication steps we studied were mixed acid (HF, HNO₃, DI water) texturing, phosphorus diffusion with POCl₃, thermal oxide growth for surface passivation, laser process for edge isolation, and PECVD of SiN_x:H for surface passivation and antireflection coating. By optimizing the processing steps, we achieved a conversion efficiency, open circuit voltage, short circuit current, and fill factor as high as 14.5%, 584 mV, 32.1 mA/cm², and 77%, respectively.     

Effect of surface morphology on screen printed solar cells

Surface texturing is well known as one of the major paths to improving the efficiency of silicon solar cells by increasing the short circuit current through effective photon trapping. However, the effects of the pyramids created after surface texturing on the other properties remain obscure. In this work, we studied the effect of the surface morphologies on the formation of both the emitter layer and metal electrode using the screen printing method, which is a cost-effective method of fabricating silicon solar cells. Various textured surfaces, such as with large, small, sharp or smooth pyramids, were investigated in comparison with a flat surface. The contact resistance was measured from a TLM patterned cell by I–V measurement under dark conditions and SEM, TEM and UV–vis spectrophotometer were used to evaluate the surfaces.     

不同形貌的金字塔结构对硅片表面钝化和异质结太阳电池的影响

在晶体硅表面沉积本征非晶硅层的异质结(SHJ)太阳电池以其高效率、高稳定性、低成本和低温制备等诸多优势被人们广泛关注.在晶体硅衬底表面制绒,是提高太阳电池效率的有效途径之一.本文采用四甲基氢氧化铵(TMAH)在硅片表面制备了不同形貌的金字塔结构的硅异质结电池衬底,并应用到电池中.通过研究不同金字塔的形貌,光学特性以及电学特性,找出提高硅片钝化效果,改善异质结电池的性能的优化的金字塔结构.结果表明:2%(w)TMAH,10%(w)异丙醇(IPA)可以在硅片表面制得标准四面体金字塔结构.和其它两种金字塔结构相比较,标准四面体金字塔结构绒面衬底反射率最低,可以提高太阳电池的短路电流密度(Jsc).同时,这种结构金字塔形貌可以提高钝化效果,改善电池各项性能参数.