Effects of channel composition and gate dielectrics on the stability of a-IGZO TFTs
The electrical and optical stability of amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) related to the channel composition (the concentration of oxygen vacancy, Vo2+) and gate dielectrics are discussed. With the filling of Vo2+, the electron density (Ne) in a-IGZO decreases from 7.5 to 3.8 (×1016cm‐3) with the increase of Fermi level and decrease of density of deep charged traps, and therefore the electrical stability of TFTs decreases from A Vth of 4.5 to 10V. The optical stability of a-IGZO TFTs is also sensitive to the Vo2 +. With the increase of Vo2+ the absorption increases and Eg decreases for a-IGZO, therefore the number of generating photo-electrons increases and the stability of TFT decreases. The SiNx-gated TFT shows good electrical stability, but its optical stability is an issue, which shows a larger off-state photo leakage current (△ Id~13μA) and decrease of Vth (|A Vth|> 14V) than those of the SiO2-gated TFT (△ Id~12 nA, |△ Vth|~8V). The model of charge trapping at the interface of gate dielectric/a-IGZO is only valid for the mechanism of electrical stability. It is proposed that due to the larger absorption of visible light of SiNx gate dielectric, and the smaller △EV between SiNx and a-IGZO film, the photo created holes carriers in a-IGZO channel can be injected more easily into SiNx during light on resulting a significant increase of Ne in a-IGZO, therefore an apparent decrease of Vth for TFT.
a-IGZO TFTs Vo2+ gate dielectrics electrical stability optical stability
J.K. Yao S.D. Zhang
Shenzhen Graduate School, Peking University, Shenzhen 518055, PRC Shenzhen Graduate School, Peking University, Shenzhen 518055, PRC institute of Microelectronics, Pek
国际会议
China Display/Asia Display 2011(2011年中国显示/亚洲显示会议)
江苏昆山
英文
373-376
2011-11-07（万方平台首次上网日期，不代表论文的发表时间）