Surface potential study of amorphous In-Ga-Zn-O thin film transistors

In this paper, we report on surface potentiometry in the channel region of operating amorphous In–Ga–Zn–O thin film transistors by scanning kelvin probe microscopy. Important parameters including the field-effect mobility and source/drain contact resistance are extracted from the channel potential profile. We find that the channel potential as a function of gate/drain bias can be described by the standard metal oxide semiconductor field effect transistor (MOSFET) equation incorporated with two nonideal factors: the gate-voltage-dependent field-effect mobility and the source/drain contact resistance.