Angle-Resolved Photoemission Spectroscopy on Emergent Quantum Materials
Cheng-Maw Cheng1,2*, Shih-Chang Weng1, Wei-Chuan Chen1, Je-Wei Lin1, Ku-Ding Tsuei1, Chao-Kuei Lee2,3, Shih-Hsun Yu4, Mitch Ming-Chi Chou4, Ching-Wen Chang2, Li-Wei Tu2, Hung-Duen Yang2, Chien-Ming Tu5, Chih-Wei Luo5, Marin M. Gospodinov6, Ben Bang-Yu Hsu7, Alan Heeger7
1National Synchrotron Radiation Research Center, Hsinchu, Taiwan
2Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
3Department of Photonics, National Sun Yat-sen University, Kaohsiung, Taiwan
4Department of Materials and Optoelectronics Science, National Sun Yat-sen University, Kaohsiung, Taiwan
5Department of Electrophysics, National ChiaoTung University, Hsinchu, Taiwan
6Institute of Solid State Physics, Bulgarian Academy of Sciences, Sofia, Bulgaria
7Center for Polymers and Organic Solids, University of California Santa Barbara, Santa Barbara , CA, USA
* presenting author:Cheng-Maw Cheng,
Angle-resolved photoemission spectroscopy (ARPES) is the most general tool to probe band structure, low-lying excitations or spectral function mapping. The technique has had major impacts on a number of important fields, such as graphene based materials, topological insulators, transition metal dichalcogenides (TMDs), nanostructure and Weyl semimetals. In this talk, I will present our recent results on the electronic structure of Sb-based topological insulators and high mobility semiconducting polymers. In Sb-based topological insulators, we derive the electronic structure of highly crystalline Sb2Te3-xSex single crystals with varied Se content studied with angle-resolved photoemission spectra. The result of band mapping reveals that the Sb2Te3-xSex compounds behave as a p-type semiconductor and have an isolated Dirac cone of a topological surface state, which are highly favored for spintronic and thermoelectric devices because of the dissipationless surface state and the decreased scattering from bulk bands. In high mobility semiconducting polymers, a highly oriented semiconducting polymer thin films can be formed by directed self-assembly of the high-solubility asymmetric molecular backbones with strong van der Waals interactions in the solid state, enabling for the FIRST TIME the direct determination of the electronic structure of highly aligned, crystalline semiconducting polymer chains. The density of states of the semiconducting polymer measured by ARPES is in agreement with the band structure calculated by density functional theory (DFT) using the structure of the crystalline polymer determined by multiple diffraction methods.

Keywords: ARPES, topological insulator, high mobility semiconducting polymer