TFT circuit integration in a-Si:H technology

Although hydrogenated amorphous silicon (a-Si:H) is inherently disadvantaged in terms of speed and stability compared to polycrystalline or crystalline Si, there is an overwhelming need for this mature technology in several newly emerging and significant application areas. Here, the question arises as to whether circuit techniques can be employed to compensate for its intrinsic material shortcomings so as to meet performance requirements. The paper reviews precisely these challenges. Specifically, it addresses the development of compact thin film transistor (TFT) circuit models and examines design considerations pertinent to thin film circuits, such as on-pixel current drivers and amplifiers, whose integration requires nonconventional design solutions to deal with the high material resistivity and high instability. The family of circuits presented here are critical to two application areas: the active matrix organic light emitting diode (AMOLED) display and digital fluoroscopy for medical applications.