Band structure of silicon and germanium thin films based on first principles

被引:0
作者
吴学科 [1 ,2 ]
黄伟其 [2 ]
黄忠梅 [3 ]
秦朝建 [4 ]
董泰阁 [2 ]
王刚 [2 ]
唐延林 [2 ]
机构
[1] College of Big Data and Information Engineering, Guizhou University
[2] Institute of Nanophotonic Physics, Guizhou University
[3] State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education),and Department of Physics, Fudan University
[4] State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences
基金
中国国家自然科学基金;
关键词
direct band gap; first principles calculation; quantum confinement effect; nanofilms;
D O I
暂无
中图分类号
O471.5 [半导体能带结构];
学科分类号
070205 ; 080501 ; 0809 ; 080903 ;
摘要
In nanomaterials, optical anisotropies reveal a fundamental relationship between structural and optical properties, in which directional optical properties can be exploited to enhance the performance of optoelectronic devices. First principles calculation based on density functional theory(DFT) with the generalized gradient approximation(GGA) are carried out to investigate the energy band gap structure on silicon(Si) and germanium(Ge) nanofilms. Simulation results show that the band gaps in Si(100) and Ge(111) nanofilms become the direct-gap structure in the thickness range less than 7.64 nm and7.25 nm respectively, but the band gaps of Si(111) and Ge(110) nanofilms still keep in an indirect-gap structure and are independent on film thickness, and the band gaps of Si(110) and Ge(100) nanofilms could be transferred into the direct-gap structure in nanofilms with smaller thickness. It is amazing that the band gaps of Si;Ge;Si;sandwich structure become the direct-gap structure in a certain area whether(111) or(100) surface. The band structure change of Si and Ge thin films in three orientations is not the same and the physical mechanism is very interesting, where the changes of the band gaps on the Si and Ge nanofilms follow the quantum confinement effects.
引用
收藏
页码:482 / 486
页数:5
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