High gain complementary inverters based on comparably-sized IGZO and DNTT source-gated transistors

Abstract

We report the first implementation of a complementary circuit using thin-film source-gated transistors (SGTs). The n-channel and p-channel SGTs were fabricated using the inorganic and organic semiconductors amorphous InGaZnO (IGZO) and dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT), respectively. The SGTs exhibit flat output characteristics and early saturation (dV_DSAT/dV_GS = 0.2 and 0.3, respectively), even in the absence of lateral field-relief structures, thanks to the rectifying source contacts realized with Pt and Ni, respectively. Hence, the complementary inverter shows excellent small-signal gain of 368 V V⁻¹ and noise margin exceeding 94% of the theoretical maximum. We show that the trip point of such inverters can be tuned optically, with interesting applications in compact detectors and sensors. Numerical simulation, using Silvaco ATLAS, reveals that optimized and monolithically-integrated SGT-based complementary inverters may reach a small-signal gain over 9000 V V⁻¹, making them highly suited to low and moderate speed digital thin-film applications. This proof-of-concept demonstration provides encouraging results for further integration and circuit level optimizations.