Polysilanes Doped with Phosphorus by Neutron Transmutation Method

中子嬗变法掺磷聚硅烷

• 批准号: 06640441
• 负责人: MATSUYAMA Tomochika
• 金额: $ 1.15万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640441/
• 关键词: Polysilane; P-Doped polysilane; n-Type semiconductor; Low-dimensional silicon semiconductor; Neutron transmutation doping; Impurity analysis; Number-averabe molecular weight; Neutron activation analysis; 低次元半導体; 低次元系半導体

If silicon skeleton of polysilane is substitutionally doped with phosphorus, polysilanes become low-dimensional silicon semiconductors with P-impurity. At the present stage, such P-doped polysilanes are available only by means of the neutron transmutation of ^<30>Si. Since the concentration of phosphorus is about 0.1ppm for thermal neutron flux up to 10^<18>/cm^2, the preparation of puriferd polysilanes is an important factor to investigate the physical properties of P-doped polysilanes without perturbation by other impurities.In the present study, we attempted to prepare highly purified polysilanes using the reductive coupling of di-or tri-chlorosilanes with sodium in refluxing toluene. Then a neutron activation method was used in quantitative analysis of impurity traces. It was found that the polysilanes were mainly contaminated by Cl and Na ascribable to the by-product NaCl and the Cl end group in polymers. The content of both impurities in these polymers was distributed in the range of about 10^<-5> to 10^<-1>/monomer unit. Further development of purification procedure is needed for the investigation of the intrinsic properties of P-doped polysilanes. We also studied a scheme to prepare polysilanes doped with phosphorus at much higher level.Quantitative analysis of end group in polymer is valid for determination of its numberaverage molecular weight. Since the polysilanes synthesized above contain Cl end groups, neutron activation analysis of the Cl end groups was applied to determine their numberaverage molecular weight. It was revealed that their molecular weight in some cases go up to 10^7. This fact implies that di-or tri-chlorosilanes are polymerized into extremely high molecular weight polymers. Therefore, if their molecular weight is regulated and their cast films are easily formed, it is expected that we can obtain various polymers with unique properties depending on molecular weight.

如果聚硅烷的硅骨架被磷取代掺杂，聚硅烷就成为含有P型杂质的低维硅半导体。在现阶段，此类P掺杂聚硅烷只能通过^ 30 Si的中子嬗变来获得。由于对于热中子通量高达10^<18>/cm^2，磷的浓度约为0.1ppm，因此纯化聚硅烷的制备是研究P掺杂聚硅烷的物理性质而不受其他杂质干扰的重要因素。在本研究中，我们尝试使用二氯硅烷或三氯硅烷与钠在回流甲苯中的还原偶联来制备高度纯化的聚硅烷。然后采用中子活化法对痕量杂质进行定量分析。研究发现，聚硅烷主要受到Cl和Na的污染，这归因于副产物NaCl和聚合物中的Cl端基。这些聚合物中两种杂质的含量分布在约10 ^ -5 至10 ^ -1 /单体单元的范围内。研究 P 掺杂聚硅烷的固有性质需要进一步开发纯化程序。我们还研究了制备高水平磷掺杂聚硅烷的方案。聚合物端基的定量分析对于测定其数均分子量是有效的。由于上面合成的聚硅烷含有Cl端基，因此应用Cl端基的中子活化分析来测定它们的数均分子量。据透露，在某些情况下它们的分子量高达 10^7。这一事实意味着二氯硅烷或三氯硅烷聚合成极高分子量的聚合物。因此，如果调节它们的分子量并且易于形成它们的流延膜，则期望我们可以获得具有取决于分子量的独特性能的各种聚合物。