2023/12/18 by Shuhan Liu, Shengman Li, Qing Lin +5 · 1 citation
Engineering · #Advanced Memory and Neural Computing #Advancements in Semiconductor Devices and Circuit Design #Semiconductor materials and devices
paper · doi:10.1109/led.2023.3344370
openalex publication_date 2023/12/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
We demonstrate a back-end-of-line (BEOL) compatible 2T gain cell consisting of n-type indium-tin-oxide (ITO) MOSFET as a write transistor and p-type carbon nanotube (CNT) MOSFET as a read transistor. The opposite polarities help counteract the capacitive coupling in gain cells operating with voltage sensing: the drop of the storage node voltage due to the capacitive coupling with the write wordline (gate of a write nMOSFET) is fully recovered at the time of enabling the read wordline (source of a read pMOSFET) for readout. With the low leakage of an ITO nMOSFET and the opposite polarity of the read transistor, retention time of more than 500 s is achieved at zero-volt standby voltage. The results suggest that the hybrid combination of n-ITO and p-CNT is a promising approach to improve gain cell operation in terms of read margin, retention, and read speed for 3D integrated all-BEOL gain cell memory above the silicon FET logic layer.