
OTFT, IGZO, LTPS & aSi TFT and OLED

What are the differences between IGZO model and ASi model?
Answer:
From the model point of view, the differences between aSi TFT model and IGZO model are

Relations between subgap DOS (density of state) and effective mobility are not clear because the fitting equations are used.

In aSi TFTs, localized charge is significantly larger than freecarrier charge because of the energyband distribution. Therefore, the localized charge accounts for the majority of the total charge is widely used.

Weak Vgs dependence of effective mobility, and

ASi TFT model is derived based on terminal voltages.
What could be an ideal IGZO model?
Answer:
The ideal IGZO model could be

The surface potential based mobility model at a given location can reflect a strong Vgs dependence and clarify the relations between processcontrolled DOS and mobility.

In IGZO TFT, The effect that localized charge is smaller than freecarrier charge out of the total induced charge is included.

Single current equation is used for IGZO TFT model, not modeled by operation point.

Surface potential based current model are used for IGZO.



