Nanoscale Research Letters ( IF 5.5 ) Pub Date : 2021-08-21 , DOI: 10.1186/s11671-021-03589-w Miaoqing Wei 1 , Dainan Zhang 1, 2 , Lei Zhang 1 , Lichuan Jin 1, 2 , Huaiwu Zhang 1, 2
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Abstract
In this paper, we have reported a multifunctional device from graphene/TiO2/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 × 1013 Jones detectability under 750 nm laser irradiation. Besides, the addition of TiO2 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
中文翻译：
基于石墨烯/TiO2/p-Si异质结的高性能多功能光电探测器和太赫兹调制器
摘要
在本文中，我们报道了一种由石墨烯/TiO 2 /p-Si 异质结制成的多功能器件，随后系统分析了器件在紫外-可见-红外波段下的光学响应和太赫兹波在 0.3-1.0 范围内的透射变化。不同偏置电压下的太赫兹频段。发现“背对背”pnp能带结构中的光电探测器，当光从石墨烯一侧照射时，光生载流子在垂直方向上的分布严重不平衡。因此，这确保了器件在750 nm 激光照射下具有高达 3.6 A/W 响应度和 4 × 10 13 Jones 可检测性的更高光学增益。此外, TiO 2 的加入该太赫兹调制器中的层在负偏压下不断加宽载流子耗尽区，从而实现太赫兹波的调制，使-15 V偏压下的调制深度达到23%。然而，当施加正偏压时，太赫兹波的传输几乎没有变化。观察到类似于电子半导体二极管，它只允许负偏压的太赫兹波通过，而阻止正偏压的太赫兹波通过。
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