Investigating the degradation behavior caused by charge trapping effect under DC and AC gate-bias stress for InGaZnO thin film transistor

Abstract

This letter investigates the degradation mechanism of amorphous indium-gallium-zinc oxide thin-film transistors under gate-bias stress. The larger Vt shift under positive AC gate-bias stress when compared to DC operation indicates that an extra electron trapping mechanism occurs during rising/falling time during the AC pulse period. In contrast, the degradation behavior under illuminated negative gate-bias stress exhibits the opposite degradation tendency. Since electron and hole trapping are the dominant degradation mechanisms under positive and illuminated negative gate-bias stress, respectively, the different degradation tendencies under AC/DC operation can be attributed to the different trapping efficiency of electrons and holes.

A Light-induced Threshold Voltage Instability Based on a Negative-U Center in a-IGZO TFTs with Different Oxygen Flow Rates

“…The parallel-shifted transfer characteristics have been explained by free-electron charge trapping at/near the gate dielectric/channel [15][16][17]. The device with an oxygen flow rate of 10 sccm reveals a larger shift in V TH , which can be explained by the fact that a-IGZO TFTs with a higher oxygen flow rate have a higher density in interstitial oxygen traps in the interface at/ near the gate dielectric/channel [12].…”

Hysteresis of Transistor Characteristics of Amorphous IGZO TFTs Studied by Controlling Measurement Speed

“…It reveals the opposite hole and electron trapping induced by the negative and positive bias during the measurement, respectively. 6,7 On the other hand, V TH shift under illumination is enhanced, because light can induce much more V O 2+ to make V TH negatively shift and enhance hole trapping efficiency. 7 The reverse V TH shifts more smoothly than the forward V TH .…”

“…• C) and high on/off ratio (∼10 6 ). 1 In addition, it is highly transparent in visible light with transmittance due to its wide bandgap (∼3 eV).…”

“…These properties open up to new applications such as transparent electronics, flexible electronics, and photo sensor. 2,3 The degradation mechanism of stress induced instability [4][5][6][7][8][9][10][11][12] and the hysteresis 8,[11][12][13] of the a-IGZO TFT have been extensively discussed. There are three commonly accepted mechanisms of degradation: (I) hole/electron trapping in the interface of gate insulator, [4][5][6][7][8] …”

Temperature-Dependent Instability of Bias Stress in InGaZnO Thin-Film Transistors

“…For the a-IGZO TFTs to act as the display's backplane electronics, reliability and stability are very important. In previous studies, only the instability caused by gas ambient [15]- [19] and light issue [20], [21] have been proposed as critical issues in the application of display industry. However, TFT in active matrix display is usually influenced by heat from the light source and operated conditions [22], [23].…”