Investigation of Low-Frequency Noise Properties in High-Mobility ZnON Thin-Film Transistors

We investigate the low-frequency noise (LFN) properties of amorphous zinc oxynitride (a-ZnON) thin-film transistors (TFTs) exhibiting high field-effect mobilities ranging from 48.5 to 118.9 cm²/V · s, depending on the gas flow rates during the deposition process. The measured noise power spectral density of the drain current shows that the LFN in a-ZnON TFTs obeys the classical 1/ f noise theory, i.e., it is proportional to 1/ f ^γ with γ~1 in the frequency range from 10 Hz to 1 kHz. The LFN from the a-ZnON TFT is successfully interpreted by the correlated number fluctuation-mobility fluctuation model. The near-interface dielectric trap density (N_T ) and the Coulomb scattering coefficient (α_S) extracted from the measured LFN in a-ZnON TFTs are similar to those from the previously reported values for amorphous indium-gallium-zinc oxide TFTs. The relatively large values of N_T and α_S from the a-ZnON TFTs formed under O₂-rich environment are mainly attributed to the high degree of disorder of the a-ZnON channel layer caused by the energetically broad and high density of subgap tail states.