Analysis of Carrier Mobility in Amorphous Metal-Oxide Semiconductor Thin-Film Transistor Using Hall Effect

Carrier mobility in an amorphous metal-oxide semiconductor (AOS) thin-film transistor (TFT) was analyzed using the Hall effect. First, an amorphous Ga-Sn-O (a-GTO) TFT and that with four electrodes arranged in a square shape are fabricated.Next, a transistor characteristic of the a-GTO TFT is measured, and field-effect mobility (μ
_FE
) is calculated. Moreover, the Hall effect of the a-GTO TFT with the four electrodes is measured using a van der Pauw method, and Hall mobility (μ
_Hall
) is calculated. Finally, it is found that the dependence of μ
_FE
on the gate voltage (Vgs) is similar to that of μ
_Hall
, and the carrier mobility (μ) increases as Vgs increases. In conclusion, it is suggested that μ in the AOS TFT is strongly subject to the percolation path in the channel layer.