Highly-functional hybrid silicon single-electron devices inccoporating nanoelectromechanical structures

研究了硅基纳米机电系统(NEMS)和单电子晶体管(SETS)的共集成，以开发超越传统MOSFET和SETS的新型功能纳米器件。NEMS-MOS-SET混合模拟技术首次将三维机械模拟、静电模拟和运输模拟结合起来。基于数值结果，开发了新的SET-NEMS分析模型，并将其集成到传统的SPICE电路模拟器中。通过使用这些仿真技术，探索了两种器件概念：一种是以集成在SET中的机械可移动栅极为特征的(SET-NEMS)，另一种是SET沟道本身作为NEMS(NEMSET)。对于前一种结构，我们在绝缘体上硅衬底上制作了悬浮栅结构，并证明了悬浮栅的快速“拉入”运动能够切换库仑振荡的周期，这可以用于信号在周期中的编码，从而实现与偏置电荷无关的置位逻辑。对于后一种结构，我们成功地制作了具有悬浮量子点的硅纳米桥晶体管，并表现出明显的库仑阻塞特性，优于传统的器件。此外，我们还观察到在&lt；4.2K温度下，库仑电流峰值在有限的源漏电压范围内消失，这是由于限制在悬浮量子点中的空腔声子引起的一种新型的单电子隧穿阻塞。

Co-integration of silicon-based nanoelectromechanical systems (NEMSs) and single-electron transistors (SETs) was investigated for developing novel functional nanodevcies beyond the conventional MOSFETs and SETs. Hybrid NEMS-MOS-SET simulation technology was first developed by combining three-dimensional mechanical, electrostatic and transport simulation. Based on the numerical results, novel SET-NEMS analytical models were developed and integrated into conventional SPICE circuit simulator. By using these simulation technologies, two device concepts were explored : one which features a mechanically movable gate integrated into SETs (SET-NEMS) and another in which the SET channel itself works as NEMS (NEMSET). For the former structure, we fabricated suspended-gate structures on the silicon-on-insulator (SOD substrates and demonstrated that a rapid 'pull-in' motion of the suspended-gate enables to switch the period of Coulomb oscillation and this may be utilized for signal encoding in the periodicity realizing the offset charge independent SET logic. For the latter structure, we successfully fabricated silicon nanobridge transistors with a suspended quantum dot and demonstrated clear Coulomb blockade characteristics superior to the conventional SETs. In addition, we observed at temperatures<4.2K that Coulomb current peaks disappear for a finite range of source-to-drain voltage, which is attributable to a new type of blockade of single-electron tunneling caused by cavity phonons confined in the suspended quantum dot.