Theoretical study of grain boundaries in Si: Effects of structural disorder on the local electronic structure and the origin of band tails.
Theoretical study of grain boundaries in Si: Effects of structural disorder on the local electronic structure and the origin of band tails.
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Si晶界的理论研究：结构无序对局域电子结构的影响和带尾的起源。
DOI：
10.1103/physrevb.50.8502
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
R. Yamamoto
中科院分区：
文献类型：
--
作者：
Masanori Kohyama;R. Yamamoto
用可转移半经验紧束缚方法研究了Si中{12 2}Σ=9倾斜和<；111>；Σ=7和<；011>；Σ=3扭曲晶界的原子和电子结构。分析了除配位缺陷外的各种结构无序对Si界面局域电子结构的影响，并探讨了Si晶界带尾的来源。奇元环引起局域态密度形状的变化，其中态密度在体价带三个峰中的两个极小值处增加，在S-p混合峰处降低。四元环产生特定形状的LDO，其中尖锐的类S峰和类p峰分别向价带的底部和顶部移动，并且这两个峰之间的特征被平滑。键的扭曲，严格的键伸缩和键角的扭曲，在价带的顶部和导带的底部产生态，在LDOS的带边诱导峰值。大伸展的键产生所谓的弱键态，它由最小带隙内的成键和反键态组成。与由较小的键扭曲引起的浅带缘态相比，这些态在带隙中更深，在键和邻近原子上更具空间局域性。
The atomic and electronic structures of the {122} Σ= 9 tilt and< 111> Σ= 7 and< 011> Σ= 3 twist boundaries in Si have been examined by using the transferable semiempirical tight-binding method. The effects of various kinds of structural disorder, except coordination defects, on the local electronic structure of Si at the interfaces have been analyzed, and the origins of band tails at grain boundaries in Si have been investigated. Odd-membered rings induce the changes in the shapes of the local densities of states (LDOS’s), where the densities of states are increased at the two minima among the three peaks of the bulk valence-band DOS and are decreased at the s-p mixing peak. Four-membered rings generate the LDOS’s of a particular shape, where the sharp s-like and p-like peaks are shifted toward the bottom and the top of the valence band, respectively, and the features between these two peaks are smoothed. Bond distortions, strictly bond stretchings and bond-angle distortions, generate states at the top of the valence band and at the bottom of the conduction band, inducing the peaks at the band edges in the LDOS’s. Greatly stretched bonds generate so-called weak-bond states, which consist of the bonding and antibonding states inside the minimum band gap. These states are deeper in the band gap and are more spatially localized at the bond and neighboring atoms than the shallow band-edge states caused by smaller bond distortions.