Charge trapping in surface accumulation layer of heavily doped junctionless nanowire transistors

• Published in: Chinese physics B 2015-12, Vol.24 (12), p.587-591
• Main Author: 马刘红 韩伟华 王昊 杨香 杨富华
• Format: Article
• Language: English
• Subjects: Charge; Drains; Electric potential; Nanowires; Scattering; Transistors; Trapping; Voltage; 俘获效应; 晶体管; 激光光刻技术; 电子迁移率; 界面电荷; 纳米线; 表面层; 重掺杂
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/24/12/128101

We investigate the conductivity characteristics in the surface accumulation layer of a junctionless nanowire transistor fabricated by the femtosecond laser lithography on a heavily n-doped silicon-on-insulator wafer. The conductivity of the accumulation region is totally suppressed when the gate voltage is more positive than the flatband voltage. The extracted low field electron mobility in the accumulation layer is estimated to be 1.25 cm^2·V^-1·s^-1. A time-dependent drain current measured at 6 K predicts the existence of a complex trap state at the Si–Si O2 interface within the bandgap. The suppressed drain current and comparable low electron mobility of the accumulation layer can be well described by the large Coulomb scattering arising from the presence of a large density of interface charged traps. The effects of charge trapping and the scattering at interface states become the main reasons for mobility reduction for electrons in the accumulation region.