Thin-Film-Transistor Stability Investigation.

This program was undertaken to identify the key parameters required for stable operation of thin-film transistors TFTs, to define the range of stable operation, and to assess TFT-device reliability and yield. Lead sulfide PbS and lead selenide semiconductors were found to produce stable TFFs i.e., free from ionic-drift and carrier-trapping effects in combination with aluminum oxide Al2O3 as the gate dielectric, but lead telluride devices exhibited carrier trapping. Stable TFT operation was obtained with chromium, molybdenum, or tungsten sourcedrain electrodes, while aluminum, titanium, lead, and gold electrodes were not as satisfactory. Unsatisfactory devices were obtained with silicon dioxide as the gate insulator. Stable PbS TFT operation was demonstrated over the range from -196 to 125C.