【作者】 李振生；

【导师】 贺德衍；

【作者基本信息】 兰州大学 ， 凝聚态物理， 2006， 硕士

【摘要】 PbI₂作为优异的制备室温X射线和γ射线探测器材料而倍受关注,这是因为PbI₂具有高的原子序数(Z_Pb=82,Z_I=53)和较高的禁带宽度（E_g=2.3～2.6eV）。人们发展了多种PbI₂的制备方法,但这些方法很难得到高质量大面积的薄膜材料,限制了材料在大面积核成像探测器中的应用。在本论文研究中,我们首先探索了用水浴法制备出结晶性较好的多晶PbI₂薄膜。考虑到真空蒸发具有制备高纯、高致密和大面积薄膜以及成本低的优点,我们重点从理论和实验两个方面对真空蒸发法生长多晶PbI₂薄膜进行了较为系统的研究。重要内容有: （1） 用水浴法制备出了结晶性较好的多晶PbI₂薄膜; （2） 用真空蒸发法在普通玻璃衬底以及镀有共面梳状A1电极的玻璃衬底制备了多晶PbI₂薄膜。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电镜（TEM）、原子力显微镜（AFM）、X射线光电子能谱（XPS）、高电阻微电流仪以及可见—紫外光谱仪（UV-VIS）等材料表征手段对所制备的PbI₂多晶薄膜的结构、形貌、化学组分以及薄膜的光学性质和电学性质进行了系统的研究。在优化实验条件的基础上,用真空蒸发法制备的多晶PbI₂薄膜的组分接近理想的化学配比;在室温下的电阻率高达10¹²Ω·cm;电导激活能为E_α=0.78eV;在室温下,在100mW/cm²的白光照射下,光电导大约是暗电导的366倍,说明PbI₂膜具有很高的光敏性;利用可见—紫外吸收光谱测量计算得PbI₂薄膜的禁带宽度为2.550eV-2.590eV。 （3） 模拟了γ射线在PbI₂探测器中的响应能谱,并将模拟结果与实际器件的测试结果进行了比较。 这些工作不仅为进一步探索高质量PbI₂薄膜的制备打下了基础,而且也为PbI₂薄膜在室温核辐射探测器及X射线成像探测器方面的应用提供了有价值的参考。更多还原

【Abstract】 Lead iodide （PbI₂） has been considered as a promising material for X-ray and y-ray room temperature detector, which is due to the high-atomic number of its elements (Z_Pb=82,Z_I=53) and wide band gap（E_g =2.3².6eV）. There are many methods forpreparation PbI₂ thin film, but it is difficult to grow in large area and high quality using those techniques, so its application in large area nuclear image detector is limited. In this thesis, we first fabricated high-crystalline PbI₂ thin film with Chemical Bath Deposition. Note that an intrinsic advantage of vacuum evaporation is that it can be easily expanded for high purity, high compact and large areas in a low-cost manner, our work concentrate on both the theory and experiment about the vapor process. The main aspects of the thesis performed as follows:（1） The high-crystalline lead iodide films, were prepared with Chemical Bath Deposition.（2） The polycrystalline lead iodide films were fabricated on normal transparent glass and normal glass coated with aluminum electrode like a bar by evaporation growth in vacuum chamber. The structures, morphology, compositions and optical and electrical properties of the samples were analyzed by X-ray Diffraction Spectrum （XRD）, Scan Electron Microscopy （SEM）, Transmission Electron Microscope （TEM）, Atomic Force Microscopy （AFM）, X-ray Photoelectron Spectrum （XPS）, high resistance instrument and Visible Ultraviolet Spectrum （VIS-UV）. It was proved that the films were found to be nearly stoichiometry, the electrical resistance of lead iodide films achieved -10¹² Ω·cm;the activation energy of the dark conductivity is E_a = 0.78eV. The photo-conduction of lead iodide polycrystalline films were 366 timeslarger than the dark-conduction under the irradiating by 100mw/cm² white light, this result indicate the films have high photosensitive;The optical absorption was carried out in UV/VIS bands, and the calculated band-gap is between 2.550eV-2.590eV.（3） The response spectrum of y-ray in PbI₂ detector have been simulated, and compared with the test results.The present work is not only a solid base for further exploration on high quality PbI₂ film, but also an active endeavor in the application process as a room temperature nuclear detector and X-ray image detector.更多还原