Dielectric-Tuned Diamondlike Carbon Materials for an Ultrahigh-Speed Self-Aligned Graphene Channel Field Effect Transistor

Abstract:

The ‘DLC-GFET’, a graphene-channel field effect transistor with a diamondlike carbon (DLC) top-gate dielectric film, is presented. The DLC film was formed ‘directly’ onto the graphene channel without forming passivation interlayers using our photoemission-assisted plasma-enhanced chemical vapor deposition (PA-CVD), where the plasma was precisely controlled by significant photoemission from the sample with quite low electric power, minimizing plasma damage to the channel. The DLC-GFET exhibits clear ambipolar characteristics with a slightly positive shift of the neutral points (Dirac voltages). Relatively high transconductances were obtained as 14.6 (8.8) mS/mm in the n (p) channel modes, respectively, with a thick DLC gate dielectric of 48 nm and a long gate length of 5 μm, promising vertical scaling-down to improve the high-frequency performance. The positive shift of the Dirac voltage is due to unintentional hole doping from an oxygen species like H₂O in the DLC film into the graphene channel, suggesting that a modulation-doped DLC structure with a δ-doped oxygen (nitrogen) species for the p (n) mode will overcome high access resistance.

• Periodical: Advances in Science and Technology (Volume 77)
• Pages: 270-275
• DOI: https://doi.org/10.4028/www.scientific.net/AST.77.270
• Online since: September 2012
• Authors: Susumu Takabayashi, Meng Yang, Shuichi Ogawa, Yuji Takakuwa, Tetsuya Suemitsu, Taiichi Otsuji
• Keywords: Diamond-Like Carbon (DLC), Field Effect Transistors (FET), Graphen, Photoemission-Assisted Plasma-Enhanced Chemical Vapor Deposition (PA-CVD)

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