a‐InGaZnO thin‐film transistors for AMOLEDs: Electrical stability and pixel‐circuit simulation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92036/1/JSID17.6.525.pd

P‐11: Electrical Properties and Stability of Dual‐Gate Coplanar Homojunction Amorphous Indium‐Gallium‐Zinc‐Oxide Thin‐Film Transistor

The electrical characteristics and stabilities of dual‐gate (DG) coplanar homojunction amorphous indium‐gallium‐zinc‐oxide thin‐film transistors (a‐IGZO TFTs) are described. When the gate voltage is applied on top and bottom electrodes, the DG a‐IGZO TFT showed an excellent electrical performance with the sub‐threshold swing of 99 mV/dec, the mobility of 15.1 cm 2 /V·s and the on‐off ratio of 10 9 . Under positive bias temperature stress, the device threshold voltage shifts about +4.5V after 10,000 seconds, while its shifts under negative bias temperature stress are very small. The effect of TFT illumination is also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93526/1/1.3621023.pd

P‐11: DC/AC Electrical Instability of R.F. Sputter Amorphous In‐Ga‐Zn‐O TFTs

The paper presents the study of electrical instability of RF sputter amorphous In‐Ga‐Zn‐O (a‐IGZO) thin‐film transistor (TFT) induced by negative steady‐state (or D.C.) bias‐temperature‐stress (BTS). Similarly to positive BTS results [8], the stress time evolution of the threshold voltage shift (Δ V th ) induced by negative BTS under different stress voltages and temperatures can all be described by the stretched‐exponential model. for the first time, we also present the results for Δ V th under pulse (or A.C.) BTS. The Δ V th for positive A.C. BTS is found to have a pulse‐period dependence while a huge reduction of Δ V th is found for all negative A. C. BTS results. This might suggest the time for holes to accumulate near the a‐IGZO/ SiO 2 interface is much longer than the time for electrons. The effect of bi‐polar stressing is also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92026/1/1.3256481.pd

16.3: AC and DC Bias‐Temperature Stability of Coplanar Homojunction a‐InGaZnO Thin‐Film Transistors

We fabricated coplanar homojunction a‐IGZO TFTs that are highly stable under AC and DC bias‐temperature‐stress. For TFTs of the size W/L = 60μm/10μm, the stress‐induced threshold voltage shifts are all within −0.35 V. A comprehensive investigation of AC BTS stress polarity, pulse width, and duty cycle dependence is presented We find that higher frequency of bipolar AC pulses increases the device instability, while lower duty cycle values have the opposite effect.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98792/1/j.2168-0159.2013.tb06171.x.pd