Fully Current-Based Sub-Bandgap Optoelectronic Differential Ideality Factor Technique and Extraction of Subgap DOS in Amorphous Semiconductor TFTs

摘要

A sub-bandgap optoelectronic differential ideality factor technique is proposed for extraction of the intrinsic density-of-states (DOS) over the bandgap in amorphous semiconductor thin-film transistors (TFTs). In the proposed technique, the gate bias-dependent differential change in the difference of ideality factors ( (dDelta eta (V_{mathrm {GS}})/dV_{mathrm {GS}}) ) between dark and sub-bandgap photonic excitation condition is employed. With the sub-bandgap photons ( (hnu < E_{g}) ), the photonic excitation of electrons is confined only from the localized DOS over the bandgap. We applied the proposed technique to a-InGaZnO TFTs with (W/L = 50/25 mu ) m/ (mu ) m and extracted the energy distribution of the intrinsic DOS for the localized states over the bandgap.