Contact resistance dependent scaling-down behavior of amorphous InGaZnO thin-film transistors

Here, we report scaling effects on the electrical properties of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). The a-IGZO TFTs had same channel width/length ratio (W/L = 20), but different channel lengths (L = 20, 10, 5, and 2.5 μm). To examine the scaling-down behaviors, short-channel effects and contact resistance of the TFTs were investigated. As the channel length decreased, apparent shift of threshold voltage (Vth) and degradation of subthreshold swing (SSUB) were shown. In addition, it is also found that the field-effect mobility (μFE) was degraded as the channel length was decreased which was originated from contact resistance. Due to this contact resistance effect, drain current (IDS) was decreased for short-channel devices.