【作者】 周幼华；

【导师】 郑启光；

【作者基本信息】 华中科技大学 ， 物理电子学， 2007， 博士

【摘要】 半导体β-FeSi₂是一种潜在的性能优良的发光、光电、热电、太阳能电池材料,它可用于制作薄膜光电器件、薄膜太阳能电池、热电器件、磁性半导体器件。β-FeSi₂也是一种环保型半导体材料,其从制造、使用和废弃都可以不对生态造成破坏。论文首先综述了β-FeSi₂的基本性能、应用前景、常用的制备方法及国内外研究现状;本学位论文是围绕脉冲激光沉积法制备β-FeSi₂薄膜而开展的一系列的研究工作。（1）采用分析纯的Fe粉和Si粉为原料合成了FeSi₂合金,研究了硅粉和铁粉合成FeSi₂的动力学过程。（2）研究了飞秒激光作用在FeSi₂合金靶、Bi₄Ti₃O₁₂陶瓷靶、Cu单质靶上等离子体羽的一般规律;研究了飞秒激光作用产生的等离子体的传输规律。（3）将飞秒脉冲激光沉积法（fsPLD, femtosecond Pulse Laser Deposition）引入到β-FeSi₂薄膜的制备工艺中,并与准分子（excimer）激光沉积法进行了比较,得到了脉冲激光沉积β-FeSi₂薄膜的适宜条件;采用飞秒脉冲激光沉积法在Si（100）、Si（111）衬底上制备了单相均匀连续的β-FeSi₂薄膜,有效的解决了传统脉冲激光沉积法中产生大量微米级的微滴的技术缺陷。（4）研究了fsPLD在沉积β-FeSi₂薄膜过程中,在不同的衬底上、不同的沉积温度和退火温度下,β-FeSi₂薄膜的生长规律。研究了β-FeSi₂/Si薄膜的生长和Si衬底取向之间的关联性。（5）采用fsPLD +固相反应法（RDE, Solid-state Reaction Epitaxy）在Si（100）和Si（111）衬底上制备了β-FeSi₂薄膜,这是脉冲激光沉积β-FeSi₂薄膜的一种新的尝试。（6）采用X射线衍射仪（XRD, X-Ray Diffraction）、扫描探针显微镜（SPM, Scan Probe Microscope）、场扫描电镜（FSEM, Field Scan Electron Microscope）、能谱仪（EDS, Energy-Dispersive X-Ray Spectroscopy）、显微激光拉曼光谱仪（MRS, Micro Raman spectrophotometer）、背散射（EBSD, Electron Back Scattering Diffraction）、高分辨透射电镜（HRTEM, High Resolution Transmission Electron Microscopy）等仪器研究了薄膜的结构、组分、表面形貌;采用紫外可见光光谱仪（UV-VIS-NIR spectrophotometer）、傅立叶红外光谱仪（FTIR,Fourier- Transform Infrared Spectrophotometer）研究了薄膜的光学性质;在室温下观察到了β-FeSi₂薄膜在1.53μm的光致发光;薄膜的直接能隙约为0.85eV。（7）将在500℃的温度下沉积并保温5 h的β-FeSi₂/Si（100）薄膜制作成霍尔元件,在多功能物性测量系统（PPMS, Physical Properties Measurement System）中测得该样品的电阻率ρ1为8.28×10-3 ?cm,霍耳系数RH=4.3×102 m3/coul,该薄膜样品为P型半导体。在500℃的温度下沉积并保温5 h的β-FeSi₂/Si（100）和β-FeSi₂/Si（111）薄膜样品的I-V特性曲线观察到0.22 V和0.25 V光生伏特。（8）采用飞秒脉冲激光沉积在Si衬底上制备了多晶钛酸铋铁电薄膜。在室温下的制备的Bi₄Ti₃O₁₂薄膜呈高c轴取向的;衬底温度为500℃的温度时,Bi₄Ti₃O₁₂薄膜呈高a轴取向的。测量了所制备的Bi₄Ti₃O₁₂薄膜铁电特性和I-V特性;通过建立一个分布参数电路模型讨论了铁电特性和I-V特性曲线之间的关联性。更多还原

【Abstract】 The semiconducting low temperature phase of iron disilicide, Orthorhombic,β-FeSi₂ has attracted strong technological interest, since it is a promising material for silicon based optoelectronics, it could be grown epitaxially on Si substrates and a direct bandgap of about 0.87eV; its photo- and electroluminescence are well matched to the transmission window of optical silica fibers at 1.55μm. And it is a potential application for active component applications such as in light detectors, near-infrared sources, solar cell material and thermoelectric material.β-FeSi₂ has other excellent features, such as the rich abundance of its constituents in natural resources and its no toxicity.（1） A review of the investigation of synthesize ofβ-FeSi₂ thin films and its characteristic were present;And a summarization about pulsed laser deposition process （PLD） was present also.（2） The principle of pulsed laser deposition process were introduced, some experiment results and its discussion were present.（3） Iron powders and silicon powders with analytical pure, were used as the origin materials to synthesize a FeSi₂ alloy target by a standard ceramics sintered process. The main ingredient in the alloy target wasα-FeSi₂.（4） The even single phaseβ-FeSi₂ thin films were gained by fsPLD below 400℃, and the proper temperature of nsPLD is about 500℃; theβ-FeSi₂ thin films prepared by fsPLD were free of micro drop; the deposition efficiency at unit average laser power in the process of depositingβ-FeSi₂ thin films, the fsPLD system was 1000 times of nsPLD system.（5） X-ray Diffraction （XRD）, Field Scanning Electron Microscopy （FSEM）, Scanning Probe Microscopy （SPM）, Electron Back Scattered Diffraction pattern （EBSD）, High Resolution Transmission Electron Microscopy （HRTEM） were used to characterize the structure, composition, and properties of theβ-FeSi₂ films.（6） Fourier-Transform Raman Infrared Spectroscopy （FTRIS）, UV-VIS-NIR spectrophotometer and Raman microscope spectroscopy were used to characterize the optical properties of theβ-FeSi₂ films; the photoluminescence from the grown single phaseβ-FeSi₂/Si thin film at a wavelength of 1.53μm was observed at room temperature （20°C）. Normal incidence spectral transmittance and reflectance data indicate a minimum, direct energy gap of 0.85 eV. The two most intense lines of Raman scattering peaked at 181.3 cm-1 and 235.5 cm-1 for the film on fused quartz, but at 191.2 cm-1 and 243.8 cm-1 for the film on Si （100）, were observed. 8 Raman peaks ofβ-FeSi₂/Si at 192.9 cm-1, 243.9 cm-1 and some points were observed by a Raman microscope with 514.5nm argon laser.（7） One way to manufacture Hall cell was introduced, and a Hall cell based onβ-FeSi₂/Si （100） thin film was finished, which was deposited and sintered at 500℃for 5 hours; the resistance ratio （ρ） and Hall coefficient （RH） were measured to be 8.28×10-3 cm and 4.3×10² cm³/coul by a PPMS （Physical Properties Measurement System）, respectively. And more, another simple way for Hall coefficient measurement given matched results, also. The I -V characteristic curves ofβ-FeSi₂/Si （100） andβ-FeSi₂/Si （111） deposited at 500℃were measured by Keithley 2400 with a solar simulator; the photo voltage of the configuration forβ-FeSi₂/Si （100） andβ-FeSi₂/Si （111） were 0.22V and 0.25V, respectively.（8） The Synthesize of the polycrystalline Bi₄Ti₃O₁₂ thin films by femtosecond laser deposition on Si （111） wafers were present. The Bi₄Ti₃O₁₂ thin film deposited at room temperature （20℃） was highly c-axis-oriented; but the film deposited at 500℃was highly a-axis-oriented. A circuit with distributed constants of Bi₄Ti₃O₁₂/Si was introduced to interpret the relationship between the I-V characteristic curve and the Ferroelectric hysteresis loop of Bi₄Ti₃O₁₂ deposited on Si.更多还原