Open AccessHigh-Performance Multifunctional Photodetector and THz Modulator Based on Graphene/TiO2/p-Si Heterojunction
Author(s) -
Miaoqing Wei,
Dainan Zhang,
Lei Zhang,
Jin Li,
Huaiwu Zhang
Publication year - 2021
Publication title -
nanoscale research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.87
H-Index - 107
eISSN - 1931-7573
pISSN - 1556-276X
DOI - 10.1186/s11671-021-03589-w
Subject(s) - terahertz radiation , materials science , optoelectronics , photodetector , graphene , biasing , heterojunction , infrared , modulation (music) , semiconductor , laser , optics , transmission (telecommunications) , voltage , nanotechnology , physics , telecommunications , quantum mechanics , computer science , acoustics
In this paper, we have reported a multifunctional device from graphene/TiO 2 /p-Si heterojunction, followed by its systematical analysis of optical response in a device under ultraviolet–visible-infrared band and transmission changes of terahertz waves in the 0.3–1.0 THz band under different bias voltages. It is found that photodetector in the “back-to-back” p-n-p energy band structure has a seriously unbalanced distribution of photogenerated carriers in the vertical direction when light is irradiated from the graphene side. So this ensures a higher optical gain of the device in the form of up to 3.6 A/W responsivities and 4 × 10 13 Jones detectability under 750 nm laser irradiation. Besides, the addition of TiO 2 layer in this terahertz modulator continuously widens the carrier depletion region under negative bias, thereby realizing modulation of the terahertz wave, making the modulation depth up to 23% under − 15 V bias. However, almost no change is observed in the transmission of terahertz wave when a positive bias is applied. A similar of an electronic semiconductor diode is observed that only allows the passage of terahertz wave for negative bias and blocks the positive ones. Graphic Abstract