Examination of dimensionality for Low Dimensional Conductors Using High Pressure Transport Measurement

使用高压传输测量检查低维导体的维数

• 批准号: 07640439
• 负责人: KOYANO Mikio
• 金额: $ 1.41万
• 依托单位: Japan Advanced Institute of Science and Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640439/
• 关键词: Dimensionality of transport; Low Dimensional Conductor; Transport Properties; TiS_3; Carrier Scattering; eta-Mo_4O_<11>; Charge Density Wave; Sliding Motion; 結晶構造; 次元性; フェルミ面; 電子輸送現象; 高圧測定; 応力

I have found the following results for one dimensional semiconductor TiS_3 and Quasi two dimensional conductor eta-Mo_4O_<11>.*One dimensional semiconductor TiS_31.I have established the most optimum condition for crystal growth of TiS_3 using a chemical vapor transport technique ; A sealed quartz tube kept at high temperature end is 520ﾟC and low temperature one is 480ﾟC,the ratio of starting materials Ti : S is 1 : 4.2.The TiS_3 is an n-type impurity semiconductor. It has the 10^<17>cm^<-3> intrinsic carriers in a conduction band pinned by some impurity levels. The 10^<18>cm^<-3> donors which make a level at below 24 meV from conduction band minima donate carriers above 100K.3.Below 100 K,the impurity scattering is dominant ; while above 100 K some scattering mechanisms have occurred in addition to a conventional LA phonon scattering. The origin of the scattering are anomalous carrier scattering reflects the low dimensional band structure and (or) polar optical phonon scattering known to the case of the non-inversion semiconductors such as GaAs.4.Raman bands are observed at 295,365,553cm^<-1> due to optical-active phonons at room temperature.*Quasi two dimensional conductor eta-Mo_4O_<11>1.When the electric field beyond a threshold field is applied along the b-axis of the eta-Mo_4O_<11>, the Charge Density Wave (CDW) is depinned and contributes to the electrical conduction.2.In the bc-plane (2-dimensional conduction plane), the CDW slides along the b-axis only. It means that the sliding motion of CDW in these Quasi two dimensional conductor is one-dimensional rather than two-dimensional.3.These results suggest that the dimensionality of CDW sliding is influenced by the symmetry of nesting vector rather than the crystal structure.

我对一维半导体 TiS_3 和准二维导体 eta-Mo_4O_<11> 发现了以下结果。*一维半导体 TiS_31。我使用化学气相传输技术建立了 TiS_3 晶体生长的最佳条件；密封石英管高温端温度为520℃，低温端温度为480℃，起始材料Ti：S的比例为1：4.2。TiS_3是一种n型杂质半导体。它在导带中具有由一些杂质能级钉扎的10^<17>cm^-3>本征载流子。导带最低能级低于24meV的10^<18>cm^-3>施主在100K以上提供载流子。3.低于100K，杂质散射占主导地位；而在 100 K 以上，除了传统的 LA 声子散射之外，还发生了一些散射机制。散射的起源是反常载流子散射，反映了非反转半导体（例如 GaAs）的低维能带结构和（或）极性光学声子散射。4.由于室温下的光学活性声子，在 295,365,553cm^-1> 处观察到拉曼带。*准二维导体 eta-Mo_4O_<11>1.当沿着eta-Mo_4O_<11>的b轴施加超过阈值场的电场时，电荷密度波（CDW）被脱钉并有助于导电。2.在bc平面（二维传导平面）中，CDW仅沿着b轴滑动。这意味着CDW在这些准二维导体中的滑动运动是一维的而不是二维的。3.这些结果表明CDW滑动的维数受嵌套矢量对称性的影响而不是晶体结构的影响。