Self-alignment processed amorphous silicon ring oscillators

Amorphous silicon field-effect transistors (a-Si FET´s) have been integrated into eleven-stage ring oscillators. The inverter consists of an n-channel driver a-Si FET and an n+ a-Si load resistor. a-Si FET´s were fabricated by the self-alignment process. Ring oscillators with a gate length of 5 µm and a gate width of 120 µm achieved a propagation delay time of 210 ns, the lowest reported to date. Those with a length and width of 5 and 1200 µm, respectively, achieved 540 ns. These propagation delay times are about two orders of magnitude faster than those attained previously.