1T-DRAM With Shell-Doped Architecture

This paper reports on the usefulness of shell-doped (SD) junctionless (JL) transistor architecture for operation as capacitorless dynamic random-access memory (1T-DRAM). SD topology overcomes the problem associated with shallower potential depth in heavily doped devices, thereby enhancing the retention time (RT) along with improved scalability. The use of a thinner shell for achieving high RT is beneficial as it reduces generation and recombination of holes. The results show that an undoped core region with shell thickness (TShell) of 2 nm yields maximum retention. An SD (Nd) of 1018cm-3attains RT of ~5.5 s and ~630 ms at 27 °C and 85 °C, respectively, whereas higher Nd(1019 cm-3) shows RT of ~13 ms at 85 °C for Lg= 200 nm. SD JL transistor shows less degradation in RT with temperature. A 10 nm SD JL device with RT of ~11 ms at 85 °C demonstrates applicability as 1T-DRAM at shorter gate lengths.