Charge emission induced transient leakage currents of a-Si:H and IGZO TFTs on flexible plastic substrates

The transient off-state thermal emission leakage currents of hydrogenated amorphous silicon (a-Si) and indium gallium zinc oxide (IGZO) metal oxide thin-film transistors (TFTs) fabricated on flexible plastic substrates have been examined for the first time. The transient leakage currents resulting from the detrapping of charge in the TFT active layer were observed to decay in a 1/t power law behaviour from 2 to 100 ms after switching the TFT test structures off. The results demonstrated a uniform density of states for both types of thin-film devices and an ∼1.3× higher transient leakage current for the IGZO TFTs. It was also shown that the observed transient leakage currents result in a shot noise at the input to the data-line charge integration amplifiers that is 20 × larger than predicted by using only the conventional static DC TFT leakage current measurements.