Thin Film Transistors

Summary

Thin film transistors (TFTs) are widely used as electronic switches to turn on/off the pixels of an active‐matrix (AM) liquid crystal display (LCD) or organic light‐emitting device (OLED). This chapter introduces some basic semiconductor concepts and discusses the electronic properties of amorphous‐ and polycrystalline silicon. It describes the fundamentals and the electrical characteristics of various TFTs including poly‐silicon TFTs, organic TFTs, and oxide semiconductor TFTs. The chapter discusses the passive matrix (PM) and active matrix (AM) driving techniques to drive a LCD or an OLED display. By using TFTs in LCD and OLED pixels, the turn‐on/off and different gray levels required on each pixel can be controlled independently by AM driving, and therefore achieve much higher image quality. Modern high resolution and large‐area displays are invariably addressed by an AM driving technique using TFTs.