Quantum Confinement, Surface Roughness, and the Conduction Band Structure of Ultrathin Silicon Membranes

被引:37
作者
Chen, Feng [1 ,2 ]
Ramayya, Edwin B. [1 ]
Euaruksakul, Chanan [1 ]
Himpsel, Franz J. [1 ]
Celler, George K. [3 ]
Ding, Bingjun [2 ]
Knezevic, Irena [1 ]
Lagally, Max G. [1 ]
机构
[1] Univ Wisconsin, Madison, WI 53706 USA
[2] Xi An Jiao Tong Univ, Xian 710049, Peoples R China
[3] Soitec USA, Peabody, MA 01960 USA
关键词
silicon nanomembrane; quantum confinement; surface roughness; thermoelectric; valley splitting; THERMOELECTRIC FIGURE; SI NANOCRYSTALS; MOBILITY; PERFORMANCE; SPECTROSCOPY; SCATTERING; TRANSPORT; STRAIN;
D O I
10.1021/nn100275z
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
We report direct measurements of changes in the conduction-band structure of ultrathin silicon nanomembranes with quantum confinement. Confinement lifts the 6-fold-degeneracy of the bulk-silicon conduction-band minimum (CBM), Delta, and two inequivalent sub-band ladders, Delta(2) and Delta(4), form. We show that even very small surface roughness smears the nominally steplike features in the density of states (DOS) due to these sub-bands. We obtain the energy splitting between Delta(2) and Delta(4) and their shift with respect to the bulk value directly from the 2p(3/2)->Delta transition in X-ray absorption. The measured dependence of the sub-band splitting and the shift of their weighted average on degree of confinement is in excellent agreement with theory, for both Si(001) and Si(110).
引用
收藏
页码:2466 / 2474
页数:9
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