Modeling the Variation of Threshold Voltage, Mobility Factor and Saturation Coefficient in Amorphous Indium-Gallium-Zinc Oxide Thin Film Transistors

Amorphous oxide semiconductor thin film transistors (AOSTFTs) with SiO2 and Indium-Gallium-Zinc-Oxides (IGZO) as dielectric and semiconductor layers respectively, are characterized in the temperature range between 300 and 400 K. The behavior of the threshold voltage, mobility factor and saturation coefficient is analyzed as function of temperature. It is shown that, using the Unified Model and Extracted Method (UMEM), the output characteristics of the devices in the linear region can be well modeled at different temperatures. This is done determining the extracted model parameters at 300 K and taking into account the law of variation with temperature for each parameter, corresponding to the specific fabrication technology of the devices. In the saturation region, an abnormal reduction of the drain current is observed. This effect has to be further studied and the representation of its behavior incorporated to the model.