Abstract-Graphene/liquid crystal based terahertz phase shifters

 

Yang Wu, Xuezhong Ruan, Chih-Hsin Chen, Young Jun Shin, Youngbin Lee, Jing Niu, Jingbo Liu, Yuanfu Chen, Kun-Lin Yang, Xinhai Zhang, Jong-Hyun Ahn, and Hyunsoo Yang  »View Author Affiliations
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-18-21395&origin=search

Due to its high electrical conductivity and excellent transmittance at terahertz frequencies, graphene is a promising candidate as transparent electrodes for terahertz devices. We demonstrate a liquid crystal based terahertz phase shifter with the graphene films as transparent electrodes. The maximum phase shift is 10.8 degree and the saturation voltage is 5 V with a 50 µm liquid crystal cell. The transmittance at terahertz frequencies and electrical conductivity depending on the number of graphene layer are also investigated. The proposed phase shifter provides a continuous tunability, fully electrical controllability, and low DC voltage operation.

Abstract-Graphene/liquid crystal based terahertz phase shifters

Yang Wu, Xuezhong Ruan, Chih-Hsin Chen, Young Jun Shin, Youngbin Lee, Jing Niu, Jingbo Liu,Yuanfu Chen, Kun-Lin Yang, Xinhai Zhang, Jong-Hyun Ahn, Hyunsoo Yang

http://arxiv.org/abs/1309.1595

Due to its high electrical conductivity and excellent transmittance at terahertz frequencies, graphene is a promising candidate as transparent electrodes for terahertz devices. We demonstrate a liquid crystal based terahertz phase shifter with the graphene films as transparent electrodes. The maximum phase shift is 10.8 degree and the saturation voltage is 5 V with a 50 um liquid crystal cell. The transmittance at terahertz frequencies and electrical conductivity depending on the number of graphene layer are also investigated. The proposed phase shifter provides a continuous tunability, fully electrical controllability, and low DC voltage operation.

Abstract -Thermal stability of metal Ohmic contacts in indium gallium zinc oxide transistors using a graphene barrier layer

Jeong Eun Lee¹, Bhupendra K. Sharma², Seoung-Ki Lee¹, Haseok Jeon¹, Byung Hee Hong³, HoLeeo-Jeong¹, and Jong-Hyun Ahn²

¹School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea
²School of Electrical & Electronic Engineering, Yonsei University, Seoul 120-749, Korea
³Department of Chemistry, Seoul National University, Seoul 151-747, Korea 

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http://apl.aip.org/resource/1/applab/v102/i11/p113112_s1?isAuthorized=no

The excellent impermeability of graphene was exploited to produce stable ohmic contact at the interface between Al metal and a semiconducting indium gallium zinc oxide (IGZO) layer after high-temperature annealing. Thin film transistors (TFTs) were fabricated with and without a graphene interlayer between the Al metal and the IGZO channel region. Metal contact at the interface prepared without a graphene interlayer showed serious instabilities in the IGZO TFT under thermal annealing; however, the insertion of a graphene interlayer between the IGZO channel and the Al metal offered good stability under repeated high-temperature annealing cycles and maintained ohmic contact.

© 2013 American Institute of Physics