Characteristics of Planar Junctionless Poly-Si Thin-Film Transistors With Various Channel Thickness

• Published in: IEEE transactions on electron devices Vol. 60; no. 3; pp. 1142 - 1148
• Main Authors: LIN, Horng-Chih, LIN, Cheng-I, LIN, Zer-Ming, SHIE, Bo-Shiuan, HUANG, Tiao-Yuan
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2013; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Capacitance; Doping; Electronics; Exact sciences and technology; Fabrication; Fixed charges; junctionless (JL) transistors; Logic gates; Performance evaluation; poly-Si; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; short-channel effect; Silicon; Thin film transistors; thin-film transistor (TFT); Transistors; Performance evaluation; Voltage threshold; Impurity density; thin-film transistor (TFT); In situ; Short channel; Doped materials; Phosphorus addition; Charge density; junctionless (JL) transistors; short-channel effect; Junctionless transistor; n type semiconductor; Thin film transistor; poly-Si; Voltage capacity curve; Planar technology; Fixed charges
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2013.2239647

N-type junctionless (JL) planar poly-Si thin-film transistors (TFTs), which contain an in situ heavily phosphorous-doped channel with thickness ranging from 8 to 12 nm, were fabricated and characterized. The devices exhibit superior current drive and good control over performance variability. From C-V characterization, the ionized dopant concentration in the channel is determined to be around 2 × 10 19 cm -3 and the fixed charge density to be around -6 × 10 12 cm -2 . The negative fixed charge density is probably related to the segregation of phosphorous species at the oxide/channel interface. We also observed a reverse short-channel effect from the relationship between the threshold voltage and the channel length. One mechanism considering enhanced phosphorous segregation is proposed to explain this finding.