Ferroelectric modulation of terahertz waves with graphene/ultrathin-Si:HfO2/Si structures

• Published in: Applied physics letters Vol. 107; no. 15
• Main Authors: Jiang, Ran, Han, Zuyin, Sun, Weideng, Du, Xianghao, Wu, Zhengran, Jung, Hyung-Suk
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 12-10-2015
• Subjects: Applied physics; Dependence; Electric potential; Ferroelectric materials; Ferroelectricity; Graphene; Hafnium oxide; Illumination; Modulation; Terahertz frequencies
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4933275

Ferroelectric-field-effect-tunable modulation of terahertz waves in graphene/Si:HfO2/Si stack structure was observed. The modulation shows distinct behaviors when the samples under different gate polarities. At a negative voltage, a transmission modulation depth up to ∼74% was present without depending on the photo illumination power, whereas, at a positive voltage, the modulation of Thz wave shows dependence on the illumination power, which is ascribed to the creation/elimination of an extra barrier in Si layer in response to the polarization in the ferroelectric Si:HfO2 layer. Considering the good compatibility of HfO2 on Si-based semiconductor process, the ferroelectricity layer of Si:HfO2 may open up an avenue for the tunable modulation of Thz wave.