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 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_v = E_ph <; E_g.