Single-Scan Monochromatic Photonic Capacitance-Voltage Technique for Extraction of Subgap DOS Over the Bandgap in Amorphous Semiconductor TFTs

We report a novel technique for simultaneous extraction of subgap donor- and acceptor-like density of states [
$g_{D}(E)$
and
$g_{A}(E)$
] over the subgap energy range
$(E_{V}<E<E_{C})$
using a single-scan monochromatic photonic capacitance-voltage technique in n-channel amorphous indium–gallium–zinc–oxide thin-film transistors. In the proposed technique, we applied two different equivalent circuit models for the photoresponsive carriers excited from
${\rm g}_{D}(E)$
and
${\rm g}_{A}(E)$
under depletion
$(V_{\rm GS}<V_{\rm FB})$
and accumulation
$(V_{\rm GS}<V_{\rm FB})$
bias by employing a sub-bandgap optical source that includes a relation between photon energy
$(E_{\rm ph})$
and bandgap energy
$(E_{g})$
as
$h{\nu}=E_{\rm ph}<E_{g}$
.