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Multi-scale design and analysis for developing 1-nm-scale neosilicon quantum information devices

开发1纳米级新硅量子信息器件的多尺度设计与分析

基本信息

批准号：
16310097
负责人：
MIZUTA Hiroshi
金额：
$ 10.11万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16310097/
关键词：
First principle calculation Material and device simulation Silicon nanodot Silicon nanorod Density functional theory Nonequilibrium quantum transport Silicon nanodevice Quantum information device 材料・デバイスシミュレーショ

项目摘要

Electronics states and quantum transport properties of 'neosilicon' nanostructures (Si nanodots and nanorods) have been investigated theoretically by combining DFT (density-functional theory) based ab-initio simulation SIESTA and nonequilibrium quantum transport simulation TranSIESTA-C. For Si nanodot structures we found that a new icosahedral structure is stable with diameter of about 1 nm, and we investigated quasi-molecular electronic states formed in a strongly-coupled double Si nanodots for realizing a charge-based qubit. We observed that the two-level splitting between the bonding-like and anti-bonding-like states formed in the double dot structure largely depends on the atomistic distance and configuration of the individual dots. We therefore proposed a atomic-wire interconnect to fix both the configuration in an atomistic manner and revealed that the wavefunction coupling is strengthened via the atomic wire interconnect and the two-level splitting is enlarged. We also found that the external electric field applied parallel to the double dots enables to tune the two-level splitting.For Si nanorod structures, we simulated for the first time nanoscale Si transistors consisting of a Si nanorod with the surface terminated by hydrogen atoms as a channel and Au (111) nanoelectrodes. We analyzed the effects of interface states between the Si nanorod and Au nanoelectrods on the transmission spectra, density of states, current-voltage characteristics and quantum transport properties. We revealed that I-V characteristics of Si nanorod transistors changes from semiconductor-like nature from metallic nature as the Si nanorod length decreases. This is because the electronic states of Au atoms in the nanoleads penetrates into the Si nanorod and dominates the entire transport properties when the channel length is reduced down towards 1 nm. We also found that the Si nanorod transistor may show unique ambipolar behaviour when the gate bias is applied.

结合基于密度泛函理论（DFT）的从头算模拟SIESTA和非平衡态量子输运模拟transista - c，对“新硅”纳米结构（Si纳米点和纳米棒）的电子态和量子输运性质进行了理论研究。对于硅纳米点结构，我们发现一个新的二十面体结构是稳定的，直径约为1 nm，我们研究了在强耦合的双硅纳米点中形成的准分子电子态，以实现基于电荷的量子比特。我们观察到在双点结构中形成的类键态和反键态之间的两能级分裂在很大程度上取决于单个点的原子距离和构型。因此，我们提出了一种原子-线互连，以原子的方式固定这两种结构，并揭示了通过原子-线互连加强波函数耦合和扩大两能级分裂。我们还发现，平行于双点的外加电场可以调节双能级分裂。对于Si纳米棒结构，我们首次模拟了由表面以氢原子作为通道的Si纳米棒和Au（111）纳米电极组成的纳米级Si晶体管。我们分析了Si纳米棒和Au纳米电极之间的界面态对透射光谱、态密度、电流电压特性和量子输运特性的影响。我们发现，随着Si纳米棒长度的减小，Si纳米棒晶体管的I-V特性从半导体性质转变为金属性质。这是因为当通道长度减小到1 nm时，纳米导线中的Au原子的电子态渗透到Si纳米棒中并主导整个输运性质。我们还发现，当栅极偏压施加时，硅纳米棒晶体管可能表现出独特的双极性行为。