【作者】 白奎锋；

【导师】 关绍康； 胡俊华；

【作者基本信息】 郑州大学 ， 材料加工工程， 2013， 硕士

【摘要】 高锰硅HMS （MnSi1.73）薄膜热电材料是一种金属硅化物热电材料,它可以把废热转化为工业、居民用电,具有广泛的应用前景和巨大优势。但是目前高锰硅薄膜材料制备方法制备的薄膜普遍存在尺度不够、厚度不均匀、杂质相太多等问题。因此要寻找一种设备简单、成本低廉的方法来制备出尺寸、形貌可控的、连续均匀的MnSi1.73薄膜。本课题采用在真空条件下,用MnCl2作为Mn源,在MnCl2的气氛内加热Si衬底,生长硅锰化合物薄膜。通过采用等温接触式生长方式和非接触式生长方式来研究基板表面高锰硅物相的形成规律以及薄膜形貌的特征,以及研究不同温度和时间条件下薄膜生长厚度和时间的关系,确定生长出100nm以上、连续均匀、形貌可控的高锰硅薄膜的最佳生长条件是900℃-12h,最后通过热力学以及界面变化简单分析MnSi1.73生长规律。实验过程中,综合使用多种分析手段,通过优化不同工艺参数,分析其相变过程和界面、尺度变化规律,通过光学性质测量,分析其电子结构特征。得出以下结论：1、MnSi1.73薄膜的制备方面（1）在接触式生长方式下,500℃、600℃生成的MnSi1.73薄膜难以检测到；700℃通过扫描形貌及能谱分析,检测出此温度区间有MnSi1.73形成,但是其含量低,薄膜太薄；800℃各个温度区间可以检测到MnSi1.73薄膜存在,但薄膜表面杂质过多、有烧结残留物质存在。（2）等温非接触式生长方式制备的薄膜膜层干净、厚度均匀一致、单相。分析不同保温时间、不同温度表面形貌得知,900℃-12h制备的薄膜表面形貌最好、最均匀、平整；分析相同保温时间、不同烧结温度的薄膜厚度,发现薄膜厚度从800℃-1000℃呈现先增加后降低的趋势。最好的制备MnSi1.73薄膜的工艺参数是：真空条件下、等温非接触生长方式、900℃保温12h。2、薄膜物相反应规律及光谱性能（1）TEM分析表明,850℃-12h条件下Si基板上生长出的是MnSi1.73薄膜；部分地方有SiO₂形成。该薄膜沿着[100]晶向垂直于Si基板表面生长,HMS与Si基板的外延关系为：MnSi1.73[100]/Si[111]和MnSi1.73[011]/Si[011].（2）光谱数据分析表明,本实验制备的HMS为直接带隙,禁带宽度为0.7eV。（3）薄膜的形成规律为：500℃生成了HMS及其转变前的物相MnSi:然后600℃HMS消失全部变成MnSi;接着700℃时生成了SiO₂及少量的HMS；800℃时生成了SiO₂及HMS；然后到900℃时全部生成了HMS,没有杂质相存在；最后1000℃时生成了HMS及SiO₂。900℃薄膜厚度最厚达到了8μm左右。少量SiO₂的存在对单相HMS的生长起到了促进作用,抑制了界面以上MnSi相的生成。更多还原

【Abstract】 High manganese silicon film thermoelectric materials (MnSi1.73) is a metal silicide thermoelectric materials, which can convert waste heat into industrial and residential electricity and has wide application prospect. But now the films prepared by these methods have too many problems because of the heterogeneous reaction, such as scale is insufficient, uneven thickness, and have too much impurity phase. Therefore, we must find a new method which can easily prepared the size, morphology is controlled, and continuous uniform film.In order to prepare a better MnSi1.73film, this project use MnCl2as the Mn source, the Si substrate is heated within the atmosphere of the MnCl2in vacuum conditions, to prepare the MnSi1.73film. By using isothermal contact growth way and the isothermal non-contact way to study high manganese silicon phase formation on the substrate surface and thin film morphology characteristics. Secondly, by studying the relationship between the thickness of the film and growth time under different temperature and time, to determine the best condition to prepare the MnSi1.73is900℃-12h. Finally, we use the thermodynamics and dynamics data to research its growth law.In the experiment, a variety of analysis methods are used. Through the optimization of different process parameters, we obtained a best method to prepare the large scale, morphology controlled, continuous MnSi1.73film and analyzed the phase change and the change law of the interface. The electronic structure was measured by optical properties. The conclusions are following:1、The field on prepare MnSi1.73film(1)、Through researching the film which was prepared in contact way we know that there is no MnSi1.73film was found under500℃and600℃. Under the700℃, by scanning morphology and energy spectrum analysis we find that there is MnSi1.73to generate, but the film is too thin and the content is low. Every temperature region under800℃can determine the MnSi1.73, but the surface of the film contains too much impurities and uneven holes.(2)、The film layer which was clean, single phase, and uniform thickness was prepared in isothermal non-contact way. Compared the surface under different holding time and sintering temperature, it is find that900℃-12h is the condition which can prepare the best film surface. Compared with the film thickness under the same holding time and different sintering temperature, it was found that the film thickness showed a trend of decrease after the first increase. The best process parameters of preparing for HMS thin film is:under the condition of high vacuum, isothermal non-contact growth way,900℃-12h.2、The phase change law of HMS film and spectrum performance(1) TEM analysis indicated that under the condition of850℃for12h, the prepared HMS film along [100] crystal orientation to grow and perpendicular to the surface of the Si substrate. SiO2was generated on some parts of the film. The epitaxial relationships between HMS and Si substrate are:MnSi1.73[100]/Si [111] and MnSi1.73[011]/Si [011].(2) Spectral data analysis shows that the HMS is direct band gap and energy gap is about0.7eV.(3) The forming rule of the HMS film is as follows:The HMS and the phase before shift were generated in500℃. In600℃it all changed to MnSi. And then the SiO2and the small amount of HMS were created in700℃. The SiO2and the HMS were created in800℃. After that, the clean HMS were appeared in900℃. Lastly, the SiO2and HMS were also appeared in1000℃. The thickest film reaches8μm in900℃. The presences of a small amount of SiO2have played an important role to promote growth of the single-phase HMS and restrain the formation of the MnSi.更多还原