A Pathway to Type-I Band Alignment in Ge/Si Core鈥揝hell Nanowires

详细信息    查看全文

• 作者：Jongseob Kim ; Jung Hoon Lee ; Ki-Ha Hong
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2013
• 出版时间：January 3, 2013
• 年：2013
• 卷：4
• 期：1
• 页码：121-126
• 全文大小：516K
• 年卷期：v.4,no.1(January 3, 2013)
• ISSN：1948-7185

文摘

We investigate the electronic band structures of Ge/Si core鈥搒hell nanowires (CSNWs) and devise a way to realize the electron quantum well at Ge core atoms with first-principles calculations. We reveal that the electronic band engineering by the quantum confinement and the lattice strain can induce the type-I/II band alignment transition, and the resulting type-I band alignment generates the electron quantum well in Ge/Si CSNWs. We also find that the type-I/II transition in Ge/Si CSNWs is highly related to the direct to indirect band gap transition through the analysis of charge density and band structures. In terms of the quantum confinement, for [100] and [111] directional Ge/Si CSNWs, the type-I/II transition can be obtained by decreasing the diameters, whereas a [110] directional CSNW preserves the type-II band alignment even at diameters as small as 1 nm. By applying a compressive strain on [110] CSNWs, the type-I band alignment can be formed. Our results suggest that Ge/Si CSNWs can have the type-I band alignment characteristics by the band structure engineering, which enables both n-type and p-type quantum-well transistors to be fabricated using Ge/Si CSNWs for high-speed logic applications.

Keywords:

type-I/II transition; quantum well; quantum confinement; strain; density functional theory