Extraction of Separated Source and Drain Resistances in Amorphous Indium–Gallium–Zinc Oxide TFTs Through $C$– $V$ Characterization

Considering asymmetry caused by layout, process, and device degradation, separate extraction of the source and drain resistances, i.e.,
$R_{S}$
and
$R_{D}$
, respectively, from the total resistance
$R_{\rm TOT}$
is very important in the design, modeling, and characterization of amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs). Due to the insulated gate structure, however, separate extraction is difficult through direct-current
$I$
–
$V$
characterization. In this letter, we propose a simple and useful technique for separate extraction of
$R_{S}$
from
$R_{D}$
in a-IGZO TFTs through a two-terminal parallel-mode
$C$
–
$V$
technique. We experimentally verified the validity of the proposed technique by comparing the result with the source-to-drain resistance from the
$I$
–
$V$
characteristics.