Research On High Order Effects Of Drain Current Model For Thin-Film Transistors

Thin-film transistor(TFT) is the core device in the flat-panel displays. The reasonable device model is indispensible in the pixel and driver circuits design. The effective and accurate model is benefit to predict the circuit performance. Consequently, it is important to the TFT modeling. The drain current is the fundamental content in the modeling, thus, this paper focuses on the high-order effects in the drain current for three kinds of TFTs:Organic TFT is advantage in the low cost and the flexible display application. The temperature affects the drain current of the TFT, seriously. based on the surface potential calculation analytically, the drain current model is presented for the different temperatures.Polycrystalline silicon TFT is advantage in the high drive ability, and it is popular in the small size, high resolution display. The power consumption is large at operation. The self-heating effect maybe appears when the temperature increases. The self-heating effect shows the drain current decreases at high drain voltage in the saturation regime. In this paper, the temperature effects on the threshold voltage and the mobility are analyzed. The analytical drain current model with the self-heating effect is presented.Amorphous TFT is advantage in the uniformity at large area, and it is mature and popular in the large size display. The series resistance effect is familiar in the amorphous TFT. In this paper, assuming the constant mobility, and considering the gate-voltage-dependent series resistance, the analytical drain current is presented. Based on the thermal-field emission, the leakage current is explained by a simple current expression.In a summary,as for the organic TFT, the analytical surface-potential-based drain current model is presented, and the drain current at different temperatures are fit, successfully; as for the polycrystalline silicon TFT, the analytical threshold-voltage based drain current model is presented including the self-heating effect; as for the amorphous TFT, the analytical drain current model is presented considering the series resistance, and the analytical leakage current model is presented. The above models are based on the device physics, and are useful to the integrated circuit design.