Analysis of the temperature dependent contact resistance in amorphous InGaZnO thin film transistors

In this work, we investigate the temperature, gate voltage, and electrode metal dependences of the contact resistance, in amorphous InGaZnO thin film transistors (a-IGZO TFTs). The measurement of the contact resistance is conducted by transfer length method using Lakeshore cryogenic probe station providing vacuum and low temperature environment. It is found that the contact resistance would decrease with the increase of the gate voltage and temperature, and vary with the contact electrode of different work function. The intrinsic temperature dependent field effect mobility of the a-IGZO TFTs can also be obtained by getting rid of the influence the contact resistance. Using transmission line model, the experimental data can be well described. The results provide a more intrinsic physics in a-IGZO TFTs.