IGZO Source-Gated Transistor for AMOLED Pixel Circuit

Abstract

Maintaining good stability of the threshold voltage in the driving transistor is very important for active-matrix organic light emitting diode (AMOLED) pixel circuits. In this work, both indium-gallium-zinc-oxide (IGZO) thin-film transistor (TFT) and IGZO source-gated transistor (SGT) are used as a driving transistor in an AMOLED pixel circuit and their performance is evaluated by simulation. It is found that the IGZO SGT is less sensitive to the trap densities in the channel layer than the IGZO TFT, including oxygen vacancy (OV) state peak values, the density of tail states at E = E-C, and OV state mean energies. The IGZO SGT is also much less affected by negative bias stress and positive bias stress than the IGZO TFT. In the AMOLED pixel circuit, the OLED current has less variation when the IGZO SGT is used as the driving transistor instead of the IGZO TFT. The work shows that the IGZO SGT is a promising alternative to the conventional TFT for applications in AMOLED pixel circuits.