Self-heating and kink effects in a-Si:H thin film transistors

We describe a new physics based, analytical DC model accounting for short channel effects for hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFT´s). This model is based on the long channel device model. Two important short-channel phenomena, self-heating and kink effects, are analyzed in detail. For the self-heating effect, a thermal kinetic analysis is carried out and a physical model and an equivalent circuit are used to estimate the thermal resistance of the device. In deriving the analytical model for self-heating effect, a first order approximation and self-consistency are used to give an iteration-free model accurate for a temperature rise of up to 100°C. In the modeling of the kink effects, a semi-empirical approach is used based on the physics involved. The combined model accurately reproduces the DC characteristics of a-Si:H TFT´s with a gate length of the 4 μm. Predictions for a-Si:H TFT´s scaled down to 1 μm are also provided. The model is suitable for use in device and circuit simulators