Extraction Method of Trap Densities in TFTs Combining $C$–$V$ and F-E Methods

We propose a novel extraction method of trap densities D
_t
in thin-film transistors, which utilizes advantages of both capacitance-voltage (C-V) and field-effect conductance (F-E) methods. First, the threshold voltage V
_th
is obtained from the I-V characteristics. Next, the C-V method is used below V
_th
. Finally, the F-E method is used above V
_th
, where the surface potential φ
_s
at V
_th
obtained from the C-V method is employed as an initial φ
_s
for the F-E method. The novel extraction method can determine D
_t
from the midgap to near the electrical conductive bands.