The Source/Drain Resistance of a-IGZO TFT

摘要

Conventional bottom gate top contact (BGTC) amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) were fabricated on glass substrate by RF magnetron sputtering. The fabricated TFT exhibits a threshold voltage of ~4 V, drain-source current on/off ratio of ~3.6×107, subthreshold voltage swing of 0.65 V/dec, and a field effect mobility of 4.7 cm2/Vs extracted from trans-conductance in linear region. In this paper, we mainly investigated the dependence of the source drain series resistance (Rsd) and channel resistance on gate voltage in a-IGZO TFT. As the gate voltage inceases, both Rch and Rsd decrease, which is thought to be related to the accumulation of electrons in the channel and under the overlap region between source/drain and gate. We also find that, as channel length L decreases, the proportion of Rsd in Rtot increases, which results in the decrease of field effect mobility of about 43% for L decreases from 50 μm to 1 μm.