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

Abstract

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 g(D)(E) and g(A)(E) under depletion (V-GS<V-FB) and accumulation (V-GS < V-FB) bias by employing a sub-bandgap optical source that includes a relation between photon energy (E-ph) and bandgap energy (E-g) as h nu = E-ph < E-g.