A novel double HBT-based capacitorless 1T DRAM cell with Si/SiGe heterojunctions

We propose a novel double heterojunction bipolar transistor (DHBT)-based capacitorless one-transistor (1T) DRAM cell employing a narrow bandgap SiGe body and Si/SiGe heterojunction for a possible next-generation DRAM cell. It has a body with a narrow bandgap and a valence band offset between the source/drain and the body. Through an extended investigation via TCAD simulation, we verified the advantages of the proposed DHBT-based 1T DRAM cell, including an improved excess carrier generation rate, a high current gain, a large sensing margin, and a suppressed sensitivity to the bandgap-narrowing effect in the heavily doped source and drain.