Macroscopic assembled graphene nanofilms based room temperature ultrafast mid-infrared photodetectors

• Main Authors: Peng, Li, Liu, Lixiang, Du, Sichao, Bodepudi, Srikrishna Chanakya, Li, Lingfei, Liu, Wei, Lai, Runchen, Cao,Xiaoxue, Fang, Wenzhang, Liu, Yingjun, Liu, Xinyu, Lv, Jianhang, Abid, Muhammad, Liu, Junxue, Jin, Shengye, Wu, Kaifeng, Lin, Miao-Ling, Cong, Xin, Tan, Ping-Heng, Zhu, Haiming, Xiong, Qihua, Wang, Xiaomu, Hu, Weida, Duan, Xianfeng, Yu, Bin Yu, Xu, Zhen, Xu, Yang, Gao, Chao
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2023
• Subjects: Science::Chemistry; Graphene Nanofilm; Heterojunction
• Online Access: https://hdl.handle.net/10356/170787
• Institution: Nanyang Technological University

Graphene with linear energy dispersion and weak electron–phonon interaction is highly anticipated to harvest hot electrons in a broad wavelength range. However, the limited absorption and serious backscattering of hot-electrons result in inadequate quantum yields, especially in the mid-infrared range. Here, we report a macroscopic assembled graphene (nMAG) nanofilm/silicon heterojunction for ultrafast mid-infrared photodetection. The assembled Schottky diode works in 1.5–4.0 μm at room temperature with fast response (20–30 ns, rising time, 4 mm2 window) and high detectivity (1.6 × 1011 to 1.9 × 109 Jones from 1.5 to 4.0 μm) under the pulsed laser, outperforming single-layer-graphene/silicon photodetectors by 2–8 orders. These performances are attributed to the greatly enhanced photo-thermionic effect of electrons in nMAG due to its high light absorption (~40%), long carrier relaxation time (~20 ps), low work function (4.52 eV), and suppressed carrier number fluctuation. The nMAG provides a long-range platform to understand the hot-carrier dynamics in bulk 2D materials, leading to broadband and ultrafast MIR active imaging devices at room temperature. (Figure presented.).