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<sub>D</sub>(E) and g<sub>A</sub>(E)] over the subgap energy range (E<sub>V</sub> <;E<;E<sub>C</sub>) 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 g<sub>D</sub>(E) and g<sub>A</sub>(E) under depletion (V<sub>GS</sub> <; V<sub>FB</sub>) and accumulation (V<sub>GS</sub> <; V<sub>FB</sub>) bias by employing a sub-bandgap optical source that includes a relation between photon energy (E<sub>ph</sub>) and bandgap energy (E<sub>g</sub>) as h<sub>v</sub> = E<sub>ph</sub> <; E<sub>g</sub>.

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