The thin film transistor—A late flowering bloom

Abstract

The thin film transistor was the first solid-state amplifier ever patented, but has found no practical application until quite recently. The history of this device is traced from the early and unsuccessful Bell Labs experiments, through its brief resurgence in the 1960's as a competitor to the MOSFET; its second disappearance from public view followed by years of hibernation at Westinghouse Labs; its emergence in the 1970's as a candidate for forming very large area integrated circuits for flat panel displays, leading to the present era of intensive, worldwide exploitation as a device which has at last found a suitable problem to solve. The present state of the art of TFT's made of CdSe, poly- and amorphous silicon is reviewed, particularly as it pertains to their current predominant use in high resolution/high performance liquid crystal displays, followed by some views on the future for TFT's in active matrices and, possibly, in other "human size" or macro-electronic components and systems.