Surface and bulk contributions to the second-harmonic generation in Bi2Se3

被引：1
作者：
Shi, Hui [1 ]
Zhang, Yu [1 ]
Yao, Mengyu [2 ]
Ji, Fuhao [1 ]
Qian, Dong [2 ]
Qiao, Shan [3 ]
Shen, Y. R. [1 ,4 ]
Liu, Wei-Tao [1 ]
机构：
[1] Fudan Univ, Key Lab Micro & Nano Photon Struct MOE, Collaborat Innovat Ctr Adv Microstruct Nanjing, Phys Dept,State Key Lab Surface Phys, Shanghai 200433, Peoples R China
[2] Shanghai Jiao Tong Univ, Dept Phys & Astron, Shanghai 200240, Peoples R China
[3] Shanghai Inst Microsyst & Informat Technol, State Key Lab Funct Mat Informat, Shanghai 200050, Peoples R China
[4] Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA
来源：
PHYSICAL REVIEW B | 2016年 / 94卷 / 20期
基金：
中国国家自然科学基金;
关键词：
TOPOLOGICAL INSULATORS; SPECTROSCOPY; FILMS; SUSCEPTIBILITY; INTERFACES; TRANSPORT; GROWTH; STATE;
D O I：
10.1103/PhysRevB.94.205307
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
Second harmonic generation (SHG) from three-dimensional topological insulators originates from both surface and bulk, which does not allow probing of surface states unless the measurement can separate the two contributions. In this paper, we used combined measurements of transmitted and reflected SHG from epitaxially grown Bi2Se3 thin films of different thickness on BaF2, and a bulk Bi2Se3 crystal, to deduce surface and bulk nonlinear susceptibilities of Bi2Se3 separately. We found that the surface contribution to SHG was comparable to that from the bulk of the crystal, but becomes dominant in ultrathin films. In the latter case, contributions from both air/Bi2Se3 and Bi2Se3/BaF2 interfaces were significant and exhibited a strong out-of-plane polar ordering. The bulk contribution came mainly from the space charge region (SCR), which was formed by Se vacancies aggregated at the air/Bi2Se3 interface; its magnitude can provide an estimate on the field strength in the SCR. Clarification of surface and bulk contributions to SHG can help nonlinear optical techniques be used as a versatile in situ probe for topological insulators.
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页数：8
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