Relationship between Detrapping of Electrons and Negative Gate Bias during Recovery Process in a‐InGaZnO Thin Film Transistors

Abstract

The relationship between detrapping of electrons and negative gate bias in amorphous InGaZnO thin film transistors (a‐IGZO TFTs) is investigated. In these devices, positive gate‐bias stress (PBS) traps electrons at the gate insulator (GI) or at the interface between the channel and the GI, and creates acceptor‐like states, which the authors speculate may be oxygen interstitials or zinc vacancies. In contrast, negative gate‐bias stress (NBS) increases donor‐like states, which are speculated as ionized oxygen vacancies, near the interface. When subsequent negative gate bias (SNB) is applied to a TFT after PBS, electrons are detrapped and donor‐like states are increased simultaneously. Measurements with various SNB and PBS conditions suggests that SNB accelerates detrapping of electrons, and that those detrapped electrons interrupts the increase of donor‐like states.