Characterization of instability in amorphous silicon thin-film transistors

Abstract

Instability mechanism of amorphous silicon-silicon nitride thin-film transistors (TFTs) is examined. By investigating double-layer insulator TFTs, it is demonstrated that the instability is caused by an electrical charge stored at the interface between amorphous silicon and silicon nitride. The amount of stored charge at the interface (Q) does not depend on either drain voltage or drain current. Study on TFTs with several insulator thicknesses has shown that Q strongly depends on the band bending in the amorphous silicon that is related to the gate electric field (E) through the gate insulator. The Q-E relationship is found to be a more general expression of the dependence of threshold voltage shift on gate voltage, and is incorporated into a formula suitable for examining the interface quality.

Air‐Operable, High‐Mobility Organic Transistors with Semifluorinated Side Chains and Unsubstituted Naphthalenetetracarboxylic Diimide Cores: High Mobility and Environmental and Bias Stress Stability from the Perfluorooctylpropyl Side Chain

“…The τ of the HMDS device were 7.7 × 10 6 s and 1.1 × 10 8 s for 30 V of ON and − 20 V of OFF gate bias stress, with greater stability to OFF bias. This is the reverse of pentacene [ 70 ] and a-Si TFT [ 73 ] which are more unstable for the OFF gate bias stress than ON gate bias stress. Because τ is related to the energy barrier of generated traps and dependent on the temperature, we can assume that the activation energy for the deep donor trap is higher than that for the deep acceptor trap [ 64 , 74 ] in 8-3-NTCDI n-channel OTFTs.…”

Bias stress effect in low-voltage organic thin-film transistors

“…Carriers trapped in a-Si:H remain trapped after the gate bias has been removed. To reverse the bias stress-induced threshold voltage shift, the structural defects in the a-Si:H must be annealed at a temperature above 180°C [5,6].…”

Bias-induced threshold voltages shifts in thin-film organic transistors

“…͑2͒ results in a stretchedexponential function V th Ϸ1Ϫexp͓Ϫ(t/t 0 ) ␤ ͔ commonly observed in disordered materials. 12,15,16 The parameter N BT (t) represents the concentration of carriers in the band tail states.…”