1 research outputs found
Effect of Back-Channel Surface on Reliability of Solution-Processed In<sub>0.51</sub>Ga<sub>0.15</sub>Zn<sub>0.34</sub>O Thin-Film Transistors with Thin Active Layer
We have investigated the degradation mechanism of solution-processed
indium–gallium–zinc-oxide (IGZO) thin-film transistors.
The threshold voltage shift (ΔVth) followed a linear function under negative gate bias stress (NBS),
while it showed a stretched-exponential behavior under positive gate
bias stress. The slope of ΔVth for
stress time was rarely changed with variations below 0.3 mV/s. The
thickness of the fabricated IGZO layer (In0.51Ga0.15Zn0.34O) was approximately 10 nm. The Debye length (LD) was larger than IGZO thickness (tIGZO) due to the fully depleted active layer under NBS.
Therefore, the degradation phenomenon under NBS was related to the
adsorption at back-channel surface. The back-channel surface could
be affected by the gate bias under NBS, and the molecules adsorbed
at the IGZO layer were positively charged and induced extra electrons
by NBS. We verified that the number of positively charged adsorbates
had a proportional relationship with the ΔVth based on the two-dimensional technology computer-aided
design (TCAD) simulation. Furthermore, we investigated the degradation
phenomenon with the ΔVth equation
regarding the adsorbates, and the result confirmed that the adsorption
process could cause the linear ΔVth. We experimentally confirmed the effect of back-channel surface
by comparing the ΔVth between different
atmospheric conditions and LD. Consequently,
the reaction at the back-channel surface should be considered to develop
the metal-oxide semiconductor devices