Ultimate Limit in Optoelectronic Performances of Monolayer WSe 2 Sloping-Channel Transistors

• Published in: Nano letters 2023-07, Vol.23 (14), p.6664-6672
• Main Authors: Xie, Zhengdao, Li, Guoli, Xia, Shengxuan, Liu, Chang, Zhang, Sen, Zeng, Zhouxiaosong, Liu, Xingqiang, Flandre, Denis, Fan, Zhiyong, Liao, Lei, Zou, Xuming
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.3c01866

Atomically thin monolayer two-dimensional (2D) semiconductors with natural immunity to short channel effects are promising candidates for sub-10 nm very large-scale integration technologies. Herein, the ultimate limit in optoelectronic performances of monolayer WSe field-effect transistors (FETs) is examined by constructing a sloping channel down to 6 nm. Using a simple scaling method compatible with current micro/nanofabrication technologies, we achieve a record high saturation current up to 1.3 mA/μm at room temperature, surpassing any reported monolayer 2D semiconductor transistors. Meanwhile, quasi-ballistic transport in WSe FETs is first demonstrated; the extracted high saturation velocity of 4.2 × 10 cm/s makes it suitable for extremely sensitive photodetectors. Furthermore, the photoresponse speed can be improved by reducing channel length due to an electric field-assisted detrapping process of photogenerated carriers in localized states. As a result, the sloping-channel device exhibits a faster response, higher detectivity, and additional polarization resolution ability compared to planar micrometer-scale devices.