Comparative Study of the Low-Frequency-Noise Behaviors in a-IGZO Thin-Film Transistors With Al₂O₃ and Al₂O₃/SiNₓ Gate Dielectrics

A comparative study is made of the low-frequency noise (LFN) in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with Al2O3and Al2O3/SiNxgate dielectrics. The LFN is proportional to 1/fgamma, with gamma ~ 1 for both devices, but the normalized noise for the Al2O3/SiNxdevice is two to three orders of magnitude lower than that for the Al2O3device. The mobility fluctuation is the dominant LFN mechanism in both devices, but the noise from the source/drain contacts becomes comparable to the intrinsic channel noise as the gate overdrive voltage increases in Al2O3/SiNxdevices. The SiNxinterfacial layer is considered to be very effective in reducing LFN by suppressing the remote phonon scattering from the Al2O3dielectric. Hooge's parameter is extracted to ~6.0 times 10-3in Al2O3/SiNxdevices.