Browsing by Author "Li, Zhiwen"

Now showing 1 - 2 of 2

The effect mechanism and properties of poplar wood cross-linking modified with polyols and polycarboxylic acid
(2023) Dong, Youming; Gao, Silong; Wang, Kaili; Zhan, Xianxu; Li, Zhiwen; Zhao, Yifan; Wu, Miao; Hughes, Mark
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Although cross-linking modification by polycarboxylic acid greatly improves dimensional stability and decay resistance, it causes severe brittleness and rigidity in wood. Introducing polyols into the cross-linking network could improve the flexibility of the modified wood, however, the related research is limited, especially the relationship between the strength and the reaction. In this study, poplar wood was modified by cross-linking with 1,2,3,4-butanetetracarboxylic acid (BTCA). D-sorbitol (SO) and sucrose (SU) used as the polyols were introduced to the modification system to esterify with BTCA. The physical and mechanical properties of the resulting wood were investigated. The effect mechanism and microstructure of the wood were also examined. The findings demonstrated that a cross-linked structure was formed in wood with increased ester bonds and ample polymer filling in the lumens. SU has lower leachability than SO. Although the incorporation of polyols has lowered anti-swelling efficiency, the reduction of modulus of rupture caused by BTCA treatment could be redeemed by reducing the degree of cross-linking between BTCA and wood components, especially SO-BTCA treatment. The addition of polyols has slight impact on the modulus of elasticity of BTCA treated wood.
Waveguide-Integrated MoTe2p- i- n Homojunction Photodetector
(2022-12-27) Li, Chen; Tian, Ruijuan; Chen, Xiaoqing; Gu, Linpeng; Luo, Zhengdong; Zhang, Qiao; Yi, Ruixuan; Li, Zhiwen; Jiang, Biqiang; Liu, Yan; Castellanos-Gomez, Andres; Chua, Soo Jin; Wang, Xiaomu; Sun, Zhipei; Zhao, Jianlin; Gan, Xuetao
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Two-dimensional (2D) materials, featuring distinctive electronic and optical properties and dangling-bond-free surfaces, are promising for developing high-performance on-chip photodetectors in photonic integrated circuits. However, most of the previously reported devices operating in the photoconductive mode suffer from a high dark current or a low responsivity. Here, we demonstrate a MoTe2p-i-n homojunction fabricated directly on a silicon photonic crystal (PC) waveguide, which enables on-chip photodetection with ultralow dark current, high responsivity, and fast response speed. The adopted silicon PC waveguide is electrically split into two individual back gates to selectively dope the top regions of the MoTe2 channel in p- or n-types. High-quality reconfigurable MoTe2 (p-i-n, n-i-p, n-i-n, p-i-p) homojunctions are realized successfully, presenting rectification behaviors with ideality factors approaching 1.0 and ultralow dark currents less than 90 pA. Waveguide-assisted MoTe2 absorption promises a sensitive photodetection in the telecommunication O-band from 1260 to 1340 nm, though it is close to MoTe2's absorption band-edge. A competitive photoresponsivity of 0.4 A/W is realized with a light on/off current ratio exceeding 104 and a record-high normalized photocurrent-to-dark-current ratio of 106 mW-1. The ultrasmall capacitance of p-i-n homojunction and high carrier mobility of MoTe2 promise a high dynamic response bandwidth close to 34.0 GHz. The proposed device geometry has the advantages of employing a silicon PC waveguide as the back gates to build a 2D material p-i-n homojunction directly and simultaneously to enhance light-2D material interaction. It provides a potential pathway to develop 2D material-based photodetectors, laser diodes, and electro-optic modulators on silicon photonic chips.