Highly Reliable Oxide TFT

Oxide thin-film transistors (TFTs) have recently been attracting attention as a backplane to drive next-generation flat-panel displays. Instability of the threshold voltage under bias-temperature stress (BTS) is one of the crucial issues to be solved for the practical realization of this technology.

Based on studies of the degradation mechanism of oxide TFTs with respect to BTS, Toshiba optimized the deposition conditions of the oxide semiconductor and the annealing temperature, and controlled the hydrogen concentration in the insulators.

As a result, BTS instability was improved to within 50 mV after 2,000 seconds at 70°C with gate voltage (Vg) of ±20 V. Using this oxide TFT with high stability against BTS, we have successfully fabricated a 3.0-inch organic light-emitting diode (OLED) panel (160 × RGB × 120 pixels) with integrated gate driver circuits.

3.0-inch OLED panel driven by oxide TFTs