Characterization of trap dynamics via transient response in amorphous InGaZnO thin-film transistors

Abstract

In this paper, the transient behavior of amorphous InGaZnO thin-film transistors is quantitatively investigated to clarify the charge trapping dynamics limiting high-speed operation. The transient drain current response is characterized by varying the gate pulse duration (tp) and the operating temperature (T). A power law-based model is employed to extract key parameters (αJT0,i, QT,i, and ni), revealing two temporal regimes separated at to ≈ 7 × 10−3 s. The fast regime (R1) is governed by tunneling-mediated electron capture into shallow traps, whereas the slow regime (R2) originates from thermally assisted transport into deeper traps under electrostatic coupling to accumulated trapped charge. A clear transition in R2 response occurs near T ≈ 333 K. Activation energy (Ea) analysis yields Ea ≈ 0 eV in R1 and Ea = 0.2–0.4 eV in R2 for low T, indicating a transition from tunneling to hopping conduction. These results provide a compact framework for separating fast/slow trapping and optimizing oxide thin-film transistor operation.