The electrical and photosensitive characteristics of amorphous indiumgalliumzincoxide (a-IGZO) thin-film transistors (TFTs) related to the oxygen vacancies V̈O are discussed. With the filling of V̈O of ratio from 14 to 8, the electron density of the a-IGZO channel decreases from 7.5 to 3.8(× 1016cm-3); the saturation mobility of the TFT decreases from 3.1 to 1.4 cm2/(V · s); the threshold voltage increases from 7 to 11 V for the TFT with a lower on-current; and the subthreshold slope increases from 2.4 to 4.4 V/dec for the TFT with a higher interface defect density of 4.9 × 10 11cm-2, the worst electrical stability of Δ V th∼10 V, and a hysteresis-voltage decrease from 3.5 to 2 V. The photoreaction properties of a-IGZO TFTs are also sensitive to the oxygen-content-related absorption of the a-IGZO channel. With the lowest content of oxygen in the channel, the TFT has the largest photocurrent gain of 50 μA(Vg = 30 V; Vd = 10 V) and decrease in V th(|Δ Vth|∼ 5 V) at a high light intensity. The light-induced change of TFT characteristics is totally reversible with the time constant for recovery of about 2.5 h.
- amorphous indiumgalliumzincoxide (a-IGZO) thin-film transistor (TFT)
- electrical and photosensitive characteristics
- oxygen vacancies