Unlocking the performance limits of 2T0C DRAM with Ω-shaped-gated single-crystal In₂O₃ FETs.

Abstract

This study demonstrates high performance Ω-shaped-gated single-crystal In₂O₃ field-effect transistors (Ω-SC In₂O₃ FETs), which push the performance boundaries of oxide-based electronics. To showcase these capabilities in a demanding application, a capacitorless two-transistor (2T0C) dynamic random-access memory (DRAM) cell is fabricated based on Ω-SC In₂O₃ FETs. Specifically, a high average field-effect mobility of 321.7 cm²/V·s with an on-off ratio above 10⁹ and a steep subthreshold swing (SS) of 64.6 mV/dec are obtained for Ω-SC In₂O₃ FETs due to the single-crystal In₂O₃ channel as well as effectively enhanced electrostatic control of the Ω-shaped gate structure. The robust gate bias temperature stress stabilities, including positive and negative bias-temperature stresses, are achieved with a threshold voltage (<i>V</i>_TH) shift value of -121 and 41 mV for 10⁴ s, respectively, which is attributed to low defect density. Moreover, the high-performance capacitorless 2T0C DRAM cell based on Ω-SC In₂O₃ FETs is constructed, which presents long data retention of 10⁵ s, ultrafast access speed of 5 ns, endurance of 10¹² cycles, and storage of 3 bits.