Photoinduced doping behaviors at graphene-TiOx heterostructures by scanning tunneling spectroscopy
Chun-Hsiang Chen1*, Min-Chuan Shih2, Wei-Ting Chen2, Po-Hsun Ho3, Chun-Wei Chen3,4, Ya-Ping Chiu1,2,4
1Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan
2Department of Physics, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
3Department of Materials Science and Engineering, National Taiwan University, Taipei, 10617, Taiwan
4Taiwan Consortium of Emergent Crystalline Materials (TCECM), Ministry of Science and Technology, Taipei, 10617, Taiwan
* presenting author:Chun-Hsiang Chen,
Graphene has attracted wide attention due to its high mobility. Therefore, it has been considered as a potential candidate to replace silicon as the base material of electronic components. In the last decade, controllable doping properties of both n-type and p-type graphene have revealed by applying several approaches such as adsorption molecules, surface modification or using different substrates. In addition, the doping behavior of the charge transfer has been mentioned in the graphene/titanium suboxide(TiOx) transistor [1]. In this work, we performed scanning tunneling microscopy and spectroscopy (STM/STS) measurements to obtain the topography image and local electronic properties of the graphene/TiOx at an atomic-scale with light illumination. Results clearly reveal the charge transfer behavior between graphene and TiOx thin film by surface transfer doping and photoinduced doping with a spatial resolution. Furthermore, the degree of photoinduced charge transfer in the heavily doped (n+) area was significantly enhanced comparing to that in the lightly doped (n) area [2].

[1] P. H. Ho, Y. C. Yeh, D. Y. Wang, S. S. Li, H. A. Chen, Y. H. Chung, C. C. Lin, W. H. Wang, and C. W. Chen, ACS Nano 6, 6215 (2012).
[2] P. H. Ho, C. H. Chen, F. Y. Shih, Y. R. Chang, W. H. Wang, M. C. Shih, W. T. Chen, M. K. Li, Y. S. Shih, Y. P. Chiu, C. W. Chen, Adv. Mater. (Online, 2015)

Keywords: graphene, titanium suboxide, scanning tunneling spectroscopy, photoinduced doping, charge transfer