Quantized orbital angular momentum of light-induced conductivity in field effect transistors

Yi Jie Feng^1*, Kristan Bryan Simbulan^1,2, Tilo H. Yang¹, Chia-Jung Chu³, Ting-Hua Lu¹, Yann-Wen Lan¹

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan
²Department of Mathematics and Physics, University of Santo Tomas, Manila, Philippines
³Silicon Based Molecular Sensoring Technology CO., Taipei, Taiwan

* Presenter:Yi Jie Feng, email:yjfeng0836@gmail.com

The properties of light may be manipulated by imparting it with spin angular momentum (SAM) or orbital angular momentum (OAM). In contrast to SAM, the OAM of light can possess nearly infinite possible values, offering a wider degree of freedom for communication and information applications. As the OAM of light interacts with solid state materials, it can potentially increase the absorption of incident photons due to OAM-of-light-enhanced quadrupole and forbidden transitions, which may result in enhancing and modulating the photoconductivity of the material. In this work, silicon nanowire field effect transistors made of standard silicon-on-insulator fabrication process are used for OAM light sensing experiment. As a result, we observed a photocurrent enhancement of at least 25% for the case of light with topological charge l=5 relative to an incident fundamental light (l=0). This improvement is attributed to the enhancements of the photogating and the photoconductive effects by the OAM of light due to better light absorption and more allowed transition channels. In this approach, we have not only demonstrated increases in the photoconductivity but also experimentally revealed an additional degree of freedom to modulate the electrical properties of the field effect transistor further. These results open up the way towards a new strategy for the development of optoelectronics.

Keywords: twisted light, silicon nanowires, photogating and photoconductive effects