Conventionally, the applications of non-crystalline semiconductor based Thin Film Transistors (TFTs) are confined to large area display applications. Typically they are used in the driver circuits of pixel arrays. One of the fundamental characteristics of such TFTs is the drift in the threshold voltage V T on application of gate bias. This paper presents a novel circuit simulator based on the recursive model of V T shift and shows how the simulator can be used to explore novel analog mode continuous time applications of TFTs based on sensor actuator architectures. While operating in analog mode, V T shift causes the DC operating point of the circuit to vary. Using this circuit simulator, the concept of employing negative feedback to minimize the drain current variation in circuits made of TFTs is studied. The ideas are validated by fabricating p-type Copper phthalocyanine (CuPC) TFTs and testing the circuits.

Non-crystalline semiconductor based thin film transistors are the building blocks of large area electronic systems. These devices experience a threshold voltage shift with time due to prolonged gate bias stress. In this paper we integrate a recursive model for threshold voltage shift with the open source BSIM4V4 model of AIM-Spice. This creates a tool for circuit simulation for TFTs. We demonstrate the integrity of the model using several test cases including display driver circuits.