Aging effects on the stability of nitrogen-doped and un-doped InGaZnO thin-film transistors

The long-term electrical reliability/stability measurements, including negative bias stress and aging over 10 months of nitrogen-doped (N-doped) and un-doped amorphous InGaZnO thin-film transistors (a-IGZO TFTs) were investigated. Aged un-doped a-IGZO TFT exhibits larger threshold voltage shift (ΔVth) of 2.43 V and turn on voltage shift (ΔVon) of 5.37 V due to combination of the surface desorption of oxygen atoms and moisture adsorption. The noticeable decrease in ΔVth (0.93 V) and ΔVon (0.81 V) of in-situ nitrogen doped a-IGZO TFT indicates the surface interaction is prevented due to effective passivation of inactive oxygen׳s in the channel. After 10 months aging time, the ΔVth (~2.66 V) and ΔVon (~4.62 V) of un-doped devices were observed under the negative gate bias stress, which is comparable to ~0.83 V and ~0.85 V in nitrogen doped a-IGZO devices, respectively. The perspectives reported here shall be useful in fabricating passivation-free oxide based semiconductor TFTs for device operation in stable ambient conditions.